Review of The Complete Guide to Landscape by Mike Shaw

(subtitled Understanding, Planning, Creating, and Processing Nightscape Images)

To prepare this review, I read the book carefully, from cover to cover.

Author

Mike Shaw is a former professor of Physics and Astronomy with undergraduate and postgraduate degrees in Materials Science and Engineering, Ceramic Engineering, and Materials Engineering; from UCLA – Berkley, Ohio State University, and UCLA – Santa Barbara. He is now a full-time photographer, specialising in nightscape photography.

There are two end-member types of astrophotographer: those who were firstly photographers, and decided to photograph the ; many of these see only the as a worthwhile astrophotography target. Others were firstly visual astronomers, and decided to photograph the kinds of things they have seen. The latter often have a better grasp of the Astronomy background, and a wider repertoire of astrophotography targets. They are usually more-savvy about tracking mounts, and are better able to photograph faint targets.

Shaw has had a foot in both camps for a long time.

Publisher

This book is one of the Focal Press Books, well-known and well-regarded by the photographic community.

Layout

 The book’s main text is divided into nine Sections and seven Appendices. The traditional Foreword, Preface and Acknowledgements are followed by Section I; (Introduction and Goals of Book), 11 pages long. Shaw defines Landscape Astrophotography as combining earth-bound landscapes with a background consisting of (usually) night-time astronomical features.

 Section II is a fairly detailed (119 pages) primer on aspects of Astronomy that are relevant to Landscape Astrophography.

 Section III (71 pages long) is a primer on photography; and covers light and human vision, equipment, and techniques used to make night-time landscape images (and sequences of images, including time-lapse sequences and video captures), and concentrates on DSLR and mirrorless camera systems.

 The nuts and bolts of the book are in Sections IV – VI.

 Section IV is 78 pages about planning images. It starts with 25 targets (themes rather than specific objects), and how to photograph them (in brief summary). Some of the targets (or themes) are: Moonlit Landscape with Starry , , Cityscapes, Star Trails, Magellanic Clouds, and Borealis/Australis. (It is refreshing to see that Southern Hemisphere themes are included.) This is followed by details on choosing and scouting locations, getting weather forecasts, composing the elements of the landscape, and forecasting the locations of the astronomical features (e g Where in the sky will the Moon be in relation to the features of the landscape, and what will be its phase? At what angle will the Milky Way slant across the sky? When is , end of , and moonrise?). Shaw directs the reader to various programs, including mobile phone apps, that can help answer some of the questions, and he gives good examples of how to use them in well-integrated case-study scenarios. Next comes further information on (“Essential”) software and apps useful for planning your images, with helpful tips and examples of how to use them. Naturally, the software list is biased towards his favourites. (He seems to be an iPhone user, rather than an Android fan.) The final chapter of Section IV is concerned with accessories, including lens filters, intervalometers for taking multiple images, and speciality tripod accessories such as panorama heads and tracking mounts.

 Section V (Creating Landscape Astrophotography Images, 25 pages) is concerned with field logistics ( reconnaissance, time and cost of travel, the advisability of carrying spare items like batteries and SD cards, setting up and focussing at night etc), and troubleshooting (dressing to suit the temperature, negotiating with other photographers who want lighting arrangements that are incompatible with your requirements, from nearby towns, avoiding/removing aircraft and satellite trails in your images etc). There is little information here on things like: What aperture setting or f-stop to use? How many seconds ? Will mounting a filter on the lens improve this image?

 Section VI deals with Processing Landscape Astrophotography Images (50 pages). The first part deals with using Adobe Lightroom and Photoshop on single images. Techniques such as changing colour balance, removing blemishes like aircraft and satellite trails, increasing contrast, sharpening images, correcting lens aberrations, and adding “points” to round star images are covered in some detail here. Following the information on processing single images is a more-detailed account of how to handle multiple images such as: Incorporating multiple dark frames, stacking multiple sub-exposures to improve signal-to- noise ratio, stitching panoramas, blending tracked skies with untracked landscapes, blending bright sunset skies with darker terrestrial foregrounds, and HDR – High Dynamic Range – processing, where images of different exposures are blended to preserve brightness levels in both the brightest and darkest areas of the image.

 Section VII (32 pages) presents four detailed case studies: Orion Over Mt Whitney and Through Möbius Arch, Supermoon Over Mt Whitney, Star Trails Over Split-Rock Lighthouse, and Milky Way Over Chumash ‘Ap. Details of planning are presented, including forecasting the azimuth and time of moonset, forecasting of the Moon’s phase, forecasting (twilight vs dark sky), and selecting camera location and framing of landscape features using The Photographer’s Ephemeris app. Brief accounts of the processing workflow is included in the discussion. Each case study concludes with a concise half-page summary, from planning to post-processing.

 Section VIII is a gallery of 19 beautiful images contributed by guest astrophotographers. These are meant for inspiration. Each image is accompanied by the photographer’s name, the source of the image, and a brief Title (such as “Sydney Harbour” and “Looking South”); camera and lens used, exposure etc settings, and processing details are omitted.

 The final Section is IX – a single page addressing the question: Where do we go from here? Shaw expects the future will bring cheaper and more-powerful imaging and in-camera processing features. Better prediction of atmospheric phenomena in the future will make this style of photography easier. The growing threat of increasing light pollution in the future is a major concern. Shaw suggest to his readers that they become active landscape astrophotographers tonight, and in the near future seek out and join the community of active landscape astrophotographers, to develop their skills.

 Seven Appendices follow the main text.

 Appendix I is a thorough and very useful checklist of what equipment to take into the field.

 Appendix II summarises details of many of the images used in the book. There is a World map with a virtual push-pin for the location of each image, and a list that includes minimal details: image Title for some, the source credit, and the general features depicted (e g sunset, Moon, aurora, star trails, Milky Way). There are no details on planning, capturing, or processing the images on this list.

 Appendix III (Annual Planner) is a too-brief list of only twelve suggested targets, one for each month; such as Orion in January, star trails in April, and the Leonid meteor shower in November. There is no explanation for these choices; some are obvious, such as the timing of the three meteor showers on the list (Perseids during August, Leonids during November, and Geminids during December); but why image twilight in February only, and star trails only in April? And why not more suggested targets?

 Appendix IV is a template and instructions for a homemade planisphere. I don’t know why this is included. Figure 2.11 on p 30 shows a very nice-looking commercially-made planisphere, and how to use it. Shaw mentions that it is inexpensive, but doesn’t say where to buy it, and doesn’t include it in the “Bibliography” for Chapter 2 (maybe it went out-of-print). The template of the DIY planisphere of Appendix IV uses black stars, constellation lines and an equatorial grid on a white sky background. Details like constellation names and the date scale are rather small, and difficult to see under dim light. A sufficiently bright light would seriously degrade your dark adaptation. The equatorial grid is over-kill for a planisphere; it becomes unnecessary clutter. Also, the instructions don’t say where to pierce the back-card to make the pivot for rotating the sky map, or mention that the star map pivot hole should be put at the North Celestial Pole. In fact the instructions don’t say how to position the two pieces (star-map and horizon-mask) together. Planispheres are useful for a latitude selection of ~ 10°-15°; this one is designed for the Northern Hemisphere, and is useless to us Queenslanders, and of doubtful value even to those in the relevant Northern latitude band.

 Appendix V (Polaris Altitude) is a diagram and text deriving the geometry of the angular elevation of the North Celestial Pole (and Polaris). This would be better as a side-box in the Section III, the Astronomy primer.

 Appendix VI (The Horizon) is a similar in style to Appendix V, and is a diagram and text deriving the geometry of the distance to the horizon, given the eye-height of the photographer. This is a fairly useless exercise, especially here as an Appendix. Of much more value would be a derivation of the angular elevation of a distant landscape feature, given its distance and topographic height, while taking into account the curvature of the Earth. This would allow planning of images in rugged areas, where you need to know angular elevations of astronomical features above the skyline, not above an imaginary sea-level. You need the answer to questions like: When will the Moon be X° above the skyline (which is at Y° elevation)? The answer is: When the Moon is at X° + Y° above the sea-level horizon. Some of this information is readily available from software such as Google Earth (e g distance from you to a mountain, its height, and your elevation). The missing factor is: what is the angular elevation of the real skyline (on a curved Earth)? Such a derivation would be very useful, almost obligatory, and should be placed in the Planning text (Section IV), not at the back of the book. (The solution is easily-derived in Google Earth using simple trigonometry; from height-of-feature, height-of-observer, and distance-to-feature.)

 The final part of the book is the Index. This is too superficial. Suppose I chose one of the suggested targets in Appendix III, the Leonid meteor shower (three of the twelve suggested targets are meteor showers). The Index shows “Meteor”, “Meteor shower”, “Meteor shower composite”, and even “Meteorite” (which is irrelevant to Landscape Astrophotography); but nothing like “Meteor imaging” or “Photographing meteor showers”. Meteor (shower) photography isn’t well-covered in the text either. One of The Twenty-Five Best Landscape Astrophotography Targets (and how to Photograph Them) in Section IV is titled “Meteor/Meteor Shower”, and shows a brilliant fireball or bolide in an image of the Aurora Borealis. Unfortunately, as the image’s caption tells us, the meteor was an accidental extra captured during a campaign of aurora imaging. The camera and lens choice and settings were selected for the aurora; there is no mention whether these settings are optimal, useful, or even inappropriate for meteor photography. You would need to read through lots of text to find if there was any useful information about meteor imaging. The Index doesn’t get you there, because it is too superficial. Fortunately, I didn’t notice any examples where the Index miss-directs the reader to a page with no relevance to the entry in the Index.

 One slightly annoying feature of the book as a whole is the style of pagination. Page numbers are combined with the Section title (left pages) or the Chapter title (right pages), and written out parallel to the long edge of the page. These page/title character strings are not displayed where they would overlap full-width (or full-page without margins) illustrations. The book is lavishly illustrated; so, too-often you need to turn several leaves backwards or forwards to find the page number.

Format

The book is a cost-saving compromise... a glossy paperback. It would be a better coffee-table book in hardback, but the glossy paper wouldn’t do well in the field after the first dewy night under the stars; many pages would be irretrievably stuck together. This should have been available as an e- book; buy it online, download it, and print it out yourself. When any pages are spoilt, re-print them yourself from your own permanent *.pdf file.

Relevancy

This book hits a nice middle note; not so superficial that the information is useless whether accurate or not, nor so detailed that the reader cannot follow it. If a book is too detailed, then only experts can understand it, but would they really need it.

Some of the Appendices are of little value. See above under Layout.

Accuracy of Content

Accuracy has a number of aspects:

. Freedom from spelling and grammatical mistakes. Some might argue that these problems are mainly cosmetic, but if a book is full of easily-corrected writing mistakes, I lose some trust in what you could call factual content. e g Where a 30 seconds exposure is suggested, is that really a typo, and is 3 seconds more appropriate? English spelling and grammar have been well-filtered. I noticed only “then” instead of “than” (on p 87); but there are problems with Greek symbols for the Bayer designations of stars (on pp 19 & 21). For example; after a comment introducing the practice of using α to indicate the brightest star in a constellation, β for the next brightest etc, the text uses Sirius as an example, but calls it “Canis Majoris” rather than “α Canis Majoris”! Likewise, as a further example two sentences later, the North American Nebula is said to be near “Cygni”, not “α Cygni”! Perhaps too much of the proof- reading was done in autopilot mode.

. Compatibility between the various parts of the book. I didn’t notice any instances where the text refers to Figure #, but that Figure is irrelevant to that text. Likewise, I didn’t find instances where the Index directs the reader to the wrong pages.

. Accuracy of content. Does the book impart too much wrong information, either because the author doesn’t know his/her topic well enough, or the writing style so is garbled that you cannot pull out what you think the author means?.

The writing style is clear most of the time; I believe that what you see written is what Shaw intended.

 My comments will show a certain type of asymmetry. I will point out more things that I disagree with, than what I agree with. I set my comments out in page sequence.

 Figure 2.2 shows in successive steps, how “everything” sits in the Universe. Panel a) shows Earth plus Moon, b) shows how they sit in the , c) shows where our Solar System is in an artist’s impression of the Milky Galaxy, d) shows where our Galaxy sits in the Local Group, and so on out to the Visible Universe. Panel d) shows Milky Way, Andromeda and Triangulum Galaxies, and the two Magellanic Clouds. This diagram is quite good, showing the various galaxies mostly at appropriate relative sizes, appropriate relative distances from each other, and even at appropriate angular separations as viewed from Earth. (A minor flaw is that the Milky Way is shown as the largest of the six, whereas it is actually about one-third the diameter of the Andromeda Galaxy.) Panel a) is abominable. It shows Moon and Earth as disks of the correct relative sizes, but puts the Moon on a too-small circle centred on the Earth; a reader could misinterpret this as the Moon being in orbit only ~2 200 km above Earth’s surface (the real distance is ~400 000 km).

 Figure 2.3 is quite good too. It depicts the Milky Way Galaxy about 70mm across, with the region containing all naked-eye stars being restricted to a circle about 10mm diameter. I had this information sitting in un-coordinated fashion in my head, but this is the first diagram I’ve seen that sets this concept down in an easily-grasped way.

 Page 22 explains how to find the North Celestial Pole; and most admirably, the South Celestial Pole.

 Table 2.1 on p 24 is rather puzzling. It lists the 12 brightest stars down one column, and their host constellations down the only other column. The accompanying text extols the value of being able to locate such bright stars, but there are no instructions on how to find either the stars or their host constellations. I don’t know why this Table was included.

 The terms “golden ” (yellow light before and just after sunset/just before and after ), and “” (after sunset/before sunrise) on p 42 are familiar to landscape photographers. Contrary to Shaw’s statement they are not hour-long periods. Different people use different definitions, some using minutes before/after sunset/sunrise, others using particular angular elevations/depressions of the . At low latitudes, lighting conditions of the “golden hour” can be roughly 60 minutes, or can last all night near the Summer Solstice at high latitudes. Most photographers would say the “blue hour” is shorter, usually 20 to 30 minutes (ten minutes by some definitions based on the Sun’s angular depression below the horizon). “Blue hour” grades into night-time after 10, 20, or 30 minutes (sometimes longer).

 Shaw’s summary of twilight stages on p 42 is at odds with all other versions I have seen. Civil twilight is generally considered to be the time-interval after sunset in which people do not need artificial illumination to carry out daytime activities. Nautical twilight is the next phase, when the bright stars used in astronavigation can be clearly identified, but the sky is still bright enough for you to see the horizon clearly. ( Astro-navigation procedures require the navigator to measure the angular elevation of stars above the horizon, so stars and horizon must be clearly visible at the same time.) Astronomical twilight ends when the sky stops getting darker. Shaw’s use of 5° steps in the sun’s angle below the horizon to define the stages of twilight is probably unique; most other writers use 6° steps. Each 6° stage takes ~ 30 minutes at low latitudes (to about 30° N or S), and longer at high latitudes. His comment that “... stars really appear during astronomical twilight.” is misleading. A small number of stars can be seen (with difficult) without optical aid even when the Sun is above the horizon. (I have glimpsed Sirius, Canopus, Alpha Centauri and Arcturus with the naked eye when the Sun was above the horizon.) Also, note that Nautical Twilight is based on the notion that stars are readily visible (at least in the small telescope of a sextant). Still on p 42, Shaw writes that “Astronomical twilight...is the time when stars, constellations, and the Milky Way attain their full brightness.” Actually, their brightness is unchanging; the sky darkens, and this renders them more prominent by increasing the contrast between lower sky brightness and higher star brightness.

 Shaw’s photos to illustrate stages of twilight in Figure 3.5 are difficult to reconcile with actual experience. The photos seem too bright. Is this an artefact of post- processing, or printing of the book?

 The caption of Figure 3.6 is also misleading. It reads as though the photos represent stages of astronomical twilight; it seems to show all of twilight, not just the astronomical twilight stage.

 Figure 3.7 is a superb way to illustrate Earthshadow and the Belt of progressing up from the eastern horizon after sunset. Innovative and very effective.

 The comments on p 47 and Figure 3.8 concerning the way colour varies with azimuth are also innovative, and well-explained and illustrated.

 The inclusion of the Southern Hemisphere in Chapter 4 Aurora Borealis / Australis is very welcome. Sample images (Figure 4.1 b)), and aurora forecast websites (Figure 4.5 c) and Figure 4.6) refer to the Southern Hemisphere.

 The explanation on p 56 of Space Weather parameters as predictors of aurora displays is very weak. The presentation is jumbled: “Two of the most significant parameters...” is followed by “The third parameter of interest...” then by “A second key parameter...” Shaw doesn’t mention where to get the information in the websites he recommends. One of the best is spaceweather.com (https://www.spaceweather.com/); browse down the left side towards the bottom of the webpage. While mentioning KP (planetary k-index) as an important parameter, he doesn’t indicate which KP values correlate with high chance of aurora display (KP takes integer values from 0-9; higher numbers correlate with greater chance of an aurora display).

 A silly mistake is in Figure 5.2: the author writes “The arrows... indicate two stars...”, but the figure shows three arrows indicating three stars!

 On p 66 Shaw writes: “Close examination of the moon’s surface, even with the naked eye, reveals it to be very rough and irregular.” Not so; the naked eye sees the irregularity (mare vs highlands) only, not the roughness.

 The explanation of relationships between the Moon’s phases, its night-to-night movement through the sky, and its direction on any one night is very well done on pp 70-75.

 On p 70, Shaw has the wrong definition for the synodic month; this is the time for the Moon to cycle through its cycle of phases, not the time to orbit the Earth, especially not “...relative to a fixed position on Earth. ²” The corresponding Note 2 on p 84 gets the sidereal month’s definition wrong, too. The sidereal month doesn’t allow time for the distance that the Earth has moved around the Sun. (That movement of the Earth around the Sun is accounted for in the synodic month.) Also, Note 3 is wrong; it doesn’t take “...approximately 29 days for the moon to complete its orbit around the earth.” It takes ~29 days to pass through all the phases (synodic month); the orbit (sidereal month) takes ~27.3 days.

 The explanation on p 75 of Milky Way landscape planning needs amplifying. The best time is not necessarily restricted to 3-4 days around New Moon. Seven days after New Moon, the First Quarter sets around , so you will have a dark sky for a few from midnight to earliest twilight. Likewise the Third Quarter rises near midnight about 21 days after New Moon, so the sky will be dark from end of twilight to about midnight. Naturally, the Milky Way (or other interesting subject) needs to be in the appropriate part of the sky. So, dark sky is available for much more than 3- 4 days around New Moon.

 Also on p 75, landscape photography at Full Moon needs more explanation. Full Moon can illuminate the foreground adequately if you are facing away from the moon. If you want to image haloes or coronas around the Moon, you need to face towards it; and then the foreground will be poorly lit (i e backlit). You can’t have it both ways!

 Shaw points out that if the Full Moon is well exposed, any foreground objects can be badly underexposed, and if the foreground is well exposed, the Moon is likely to be washed out. This point can be developed further: the Moon is essentially a huge dark- to mid-grey rock lit by the Sun, so a good exposure for the Moon matches a good exposure of rocks on the Earth. At or just after sunset, the foreground is no longer strongly lit by the Sun, so it needs a considerably increase in exposure; however, the Full Moon is as strongly sunlit as ever. So, if a photo includes a well-exposed Full Moon with a well-exposed night-time foreground, there must have been some compositing; the scene is not “natural”. In the most famous of all moonrise photographs – Moonrise, Hernandez, New Mexico - by famous American landscape photographer Ansel Adams, the moon was well-exposed, but the foreground was quite dim even though the photo was taken a few seconds before sunset. (The sky is dark too, because film emulsions at the time - November 1941 - had low sensitivity to blue light, such as from the sky.)

 The “Bibliography” in “The Moon” chapter (Chapter 5) includes the book Photography: Night Sky, by Jennifer Wu & James Martin. Wu & Martin recommend setting the colour temperature of your camera to values around 4400 K to 3200 K to reproduce the night sky as blue. While any colour of sky is permissible for artistic effect, this book wrongly claims that the night sky really is blue. The night sky is blue only when the Moon is above the horizon, and the real night sky is never as blue as Wu & Martin reproduce in their book, even with the Full Moon in the sky. (They claim that they are adjusting the colour temperature to reproduce the true night sky colour; but they are wrong.) These authors also advise adjusting exposure times for point stars to include the crop factor, and to “...figure out the effective of the lens first.” This is wrong-headed thinking; the crop sensor doesn’t change the focal length of any lens to a different “effective focal length”; it tells you how much of the cone of light passed on through the lens is intercepted by the smaller sensor. Despite these shortcomings, Wu & Martin have some good stuff, especially for combining images. Use the book if you like artistry, beware if you want realism.

 On p 90 Shaw refers to the as “... a relatively rare phenomenon...” and “...only visible under completely dark skies...” This is an exaggeration; although we Queenslanders at low latitudes have it easier than others at higher latitudes (Americans and Europeans). He refers to it as being visible “...for an hour or so around when astronomical twilight begins or ends.” This is strangely worded; suggesting observation in the (“begins”) and the (“ends”), rather than the reverse sequence. Like many other authors, Shaw refers to the appearance of the zodiacal light as a cone; “triangle” would be more appropriate. Also, he is not clear about what he means by end/beginning of astronomical twilight; the transition between nautical twilight and astronomical twilight, or the transition between astronomical twilight and dark sky (i e early end or late end). My own experience is that the Zodiacal Light is prominent near the start of evening nautical twilight, and is rather difficult to see (and image) by halfway through astronomical twilight. I haven’t found any information written down anywhere about how far up (degrees of angular elevation) the Zodiacal Light extends from the horizon. Shaw suggests using a wide- angle or fisheye lens; I find a 20mm wide-angle lens that covers 60° x 42° on a crop sensor camera to be very useful. Either a 28mm or 35mm focal length lens would be appropriate on a full frame camera.

 On p 91 there is information about solar and lunar analemmas. I had never thought of the lunar analemma; very innovative by Shaw. He suggests delaying each daily photo by 51 minutes because the Moon rises an average of 51 minutes later each . The time delay varies, and the daily photos could be synchronised with the varying daily delay in moonrise time. The solar analemma photos must all be taken at the same time of day (not necessarily ), and this might not be too difficult, especially if you choose the same day of the week (52 photos) or fortnight (26 photos). The lunar analemma needs one photo per day (30 photos); less frequently would be too “gappy”. The average daily delay of 51 minutes requires photos at all different times of day (including ) every day during the month (weather permitting), which could be very inconvenient.

 On pp 78-79 Shaw discusses the timing required to have a virtually-full moon rising along with the Earthshadow/ boundary, and mentions that the Moon’s position may be “just-right” only once a year. It can even be worse; too high on the evening before Full Moon, too low the next evening on the best Full Moon of the year, especially if you want the Moon to be in a specific position in relation to the foreground scenery.

 Figure 5.12 b) explains apogee and perigee; the caption says the diagram is “not to scale”. If the diagram had been drawn to-scale you would notice that the Earth is off- centre in the Moon’s orbit, but not that the orbit is non-circular.

 On p 95 Shaw “explains” meteors as the result of frictional heating by drag against the atmosphere’s molecules. This commonly-used “explanation” is wrong. The incoming meteor is travelling so fast that it can’t push the air molecules out of the way efficiently (i e it’s moving faster than the “speed of sound” in the rarefied atmosphere). The inefficiency of “pushing-aside” leaves the atmosphere’s molecules to “pile-up” in front of the meteor; this is a high-pressure zone, and it is the pressure-rise that causes the adiabatic heating which heats the air and the meteor.

 In Chapter 7 (Meteors, Meteor Showers, Comets, Fireballs, and Bolides) there is a connection back to Chapter 6 that Shaw doesn’t mention. Meteors become meteorites if and when they hit the ground. Before they enter the atmosphere the dust grains are called . Most meteoroids never become meteors, they remain in a disk-shaped cloud centred on the sun, and concentrated towards the mean plane of the Solar System (the Ecliptic). scattered from this dust disk is seen as the Zodiacal Light.

 Shaw’s summary of the origin and age of the Milky Way on p 103 fails to distinguish between “ordinary” black holes and supermassive black holes. The one at the centre of our galaxy is supermassive (~4 - ~4½ million times our Sun’s mass). Shaw incorrectly describes our central black hole as though it was a stellar-mass “ordinary” black hole. Some black holes are suspected of growing supermassive, by sucking-in surrounding matter, such as stars, nebulae etc, in winner-takes-all fashion.

 The age of the Milky Way (p 103) can be constrained in various ways. If its form is (partly) governed by the gravitational field of the supermassive black hole at the centre, then it didn’t form before the central black hole formed (and grew to supermassive size?). Measurements of the relative abundances of various isotopes of Thorium and Uranium indicates the age of the Universe (Big Bang time) is ~13.8 billion years. Our Milky Way Galaxy must be younger than this.

 Under the heading Relative Orientations of the Earth, Solar System, and Milky Way, on p 105, Shaw claims that “...the earth’s rotational axis is, therefore, aligned within a few degrees of the plane of the Milky Way.” This is not so; the northernmost point on the Galactic Equator is at Declination ~67⅔°N (and R A ~ 00h 51m), so the Earth’s rotational axis is ~22⅓° (= 90° - 67⅔°) off the plane of the Milky Way, as the simplest sky map shows. Figure 8.3 on p 106 shows where he went wrong; in fact this diagram is probably what sent him astray. The figure is drawn as though the Earth’s axis is in the plane of the page. This would give an angle sum of 63° + 23.5° = 93.5°, or nearly 90° (for which arrangement the Earth’s axis would be exactly parallel to the Milky Way). The diagram is drawn as though the three axes (Milky Way normal axis, Solar System normal axis, and Earth’s rotational axis) are in the same plane. They aren’t. If you draw the diagram with the Earth’s rotational axis and the normal axis to the Ecliptic in the plane of the paper, then the Galactic normal axis would sit up out of the page. The plane containing the Earth’s rotational axis and the normal to the Ecliptic has its own perpendicular axis. This axis is ~30° from the Galactic normal axis, so the Galactic axis would be ~60° out of the plane of the page. The North Ecliptic Pole is on R A 18h 00m (at 23.5° N Dec), the South Ecliptic Pole is on 06h 00m (at 23.5° S Dec). If the Galactic Poles the Ecliptic Poles and Earth’s rotational poles were co-planar, they would have the same R A; instead, the North Galactic Pole is at R A 12h 51m, 27.1° N Dec, and the South Galactic Pole is at R A 00h 51m, 27.1 S Dec.

 The various images that display the appearance of the Milky Way for various times- of-day, dates, and latitudes (Figures 8.4 to 8.8) are useful but rather complicated; careful study will be rewarded with a good understanding of how the Milky Way looks in the sky. One problem is Shaw’s statement on p 108 that the Galactic Core is directly overhead at 47° S latitude. The Core has a declination of 28.9° S, so it passes overhead at 28.9° S latitude (roughly over Casino/Lismore/Ballina, in NE NSW). Latitude 47° S is south of Tasmania and South Africa, across Stewart Island (the small third island at the southern end of New Zealand), and across Patagonia in Chilean and Argentinean South America, where there are no large cities. This value (47° S) is a strange choice to illustrate the visual effect of different latitudes.

 Shaw mentions that in some nightscapes the Milky Way is given a vivid blue, green or purple colour. Interestingly, he includes in the “Bibliography” for this chapter, the book Photography: Night Sky by Jennifer Wu & James Martin; where vivid blue is treated as the normal colour for astrophotographs. As he acknowledges: “Ultimately, of course, it is entirely the choice of the photographer how to proceed.”

 In passing, Shaw mentions galaxies outside our Milky Way Galaxy; specifically the Magellanic Clouds, and the Andromeda Galaxy. The images he uses to illustrate them are almost worthless. Figure 8.11 a) is a very wide panorama including the Large Magellanic Cloud as a small feature at that scale, (just above the horizon) but not the Small Cloud. Likewise, the Andromeda Galaxy in Figure 8.11 b) is tiny in the wide angle/fisheye image. In neither case does Shaw point out for the reader the locations of these galaxies in the two images. It is nice that Shaw included a Southern Hemisphere feature as an example.

 On p 120, Shaw lists cumulonimbus clouds amongst the low-level clouds at 0 – 6 500 feet (0 - ~2 000 metres). Actually, they can grow very tall; their bases at a low level, and extending upwards 40 000 feet (~12 000 metres) or (rarely) even 70 000 feet (~21 000 metres), through mid-levels to high-levels. Figure 9.1 a) shows the correct arrangement.

 Shaw’s comment on pp 122-123 about the length and texture of aircraft contrails indicating the air’s relative humidity is true, and applicable to the air through which the aircraft are flying: at ~10 000m /~30 000 ft, but not the air at lower levels. About 75% of Earth’s atmosphere is below such high-flying aircraft; we look or image through this thicker air, as well as the overlying thin air, through which the aircraft are flying.

 On p 123 Shaw writes that air with a high absolute humidity has a higher dew point than air with a low absolute humidity. This is true (but not very useful) information, which can be misinterpreted. Weather reports and forecasts usually give relative humidity, not absolute humidity. When the relative humidity of air is high (say 95%), it is not far below its dew point. Slight cooling (as might be expected through the night), will form dew on surfaces or fog/clouds in the air, when the air cools enough to reach 100 % relative humidity (at its dew point).

 Like most explanations of dew formation, Shaw’s is poorly done. Something like a or grass on the ground will radiate heat away (as infra-red radiation – IR), and the object cools; this cools the surrounding air, and dew may form. So far so good. It is usually written (including by Shaw) that the heat is radiated away into the night sky (or Space). Generally, most authors imply (or even state explicitly) that anything that blocks this pathway to Space (such as clouds or foliage overhead) causes less cooling because of the blocking, as though by unspecified magic. Actually, the stuff overhead (clouds or foliage) is also emitting IR, including downwards, and this warms whatever is below (such as you or your camera’s lens). Any “blocking” of upward IR would heat this “block” (especially its underside), and cause it to emit more IR, especially downwards, to warm whatever objects at ground-level were cooling-off. Dew-free patches under a tree form because the tree is also radiating IR, including downward from the underside of its canopy, and this downward IR warms the ground, sometimes enough to keep it above dew point. Clouds overhead do the same; but clear air is less effective because it is less dense, so it emits fewer IR photons. That’s why clear are often colder than cloudy ones: there is less downward-IR-radiating mass above you, so fewer warming IR photons come down towards the ground.

 In Figure 9.3 (p 126), the angle for the 22° Moon halo is mentioned in b), but Shaw forgot in 9.3 b) to mention the sun- rainbow/moon-rainbow angle of 42° for red light (= 180° - 138°). This angle is important for field-of-view decisions: what focal length lens to use?

 Similarly, Figure 9.4, an image of haloes and refracted arcs around the Moon, lacks any indication of angular size. What focal length lens do you need? Incidentally, the 120° parhelion mentioned in the caption is the bright spot out to the right; something that Shaw doesn’t point out. Finally, Shaw refers to both terms sundog and parhelion (plural: parhelia) without mentioning that the terms are synonyms. The light-path for the 120° parhelion has two internal reflections off different side faces of the plate-shaped ice crystals.

 For explaining light intensities, Shaw uses a wonderful analogy. (The human eye can work with intensities from 0.001 lux to 50 000 lux.) Using such a large range of values is impractical. Shaw likens it to “... conduct(ing) all your purchases, from sticks of gum to groceries to cars to real estate, solely with individual pennies”. He then introduces the light value (LV), a logarithmic scale from about -12 to +12 for the eye’s useful sensitivity range. Increasing the LV by one unit corresponds to doubling the brightness. This is like changing denominations of coins and notes.

 The rods (the low-light-sensitive retinal cells) are concentrated in a ring on the eye’s retina about 20° angular radius from the fovea or centre of sharp vision. To see most-easily the very faintest objects, the best strategy is to put the objects’ images on this most sensitive ring, by looking about 20° away from the expected position. So far so good. Shaw expresses this offset as the width of your thumb at arm’s length, but this is wrong. A thumb at arm’s length is about 1½° wide; 20° is about the distance from your little fingertip to the “V” between your thumb and the side of your hand, when you stretch your hand out at arm’s length.

 Chapter 11 (Cameras and Lens Systems) contains various simplifications that are not critical to understanding the principles so I will confine criticism to those statements that are critical to imaging performance.

 Modern full-frame sensors have slightly better noise performance at dim levels than current crop sensors. Shaw over-cooks this difference on p 149 as “...much less noise...” for full-frame sensors. The actual difference is small, and might be outweighed by other factors, when comparing individual camera models.

 There is a very handy tip on p 150 about focussing at night on nightscape images. If you can move the focus point around the view, put it on a star for focus on the sky part of the scene, and on the foreground for focus on the landscape elements, when you take individual exposures; these will be all in focus, and can be combined more easily in the final image.

 Some DSLR cameras have the facility to lock-up the mirror before the exposure is made. This prevents blur from “mirror-slap”, and is a good feature to have. Its value can be overstated, because the vibration time (less than 1 second) is a small percentage of a typical landscape astrophotography long exposure, and makes a minimal to negligible adverse contribution to the image. Don’t despair if you want to take long exposures but your camera doesn’t have mirror lock-up. The advantage of mirror lock-up is greatest for the short exposure times when imaging in bright light (daylight) or bright targets (the Moon). During short exposures, the mirror vibrates the camera for a larger percentage of the short exposure time, and “mirror slap” is more significant. For a crop sensor camera, the mirror is smaller and lighter, so the effect on the image is less (one point back to the crop sensor camera!)

 Everyone (including Shaw on p 151) recommends using RAW file format. If you really need JPEGs, they can be made afterwards, using other software.

 Shaw ignores crop sensor cameras in the text under Field of View (p 152). Figure 11.4 b), Table 1.1, and the images in Figure 11.5 are all for full-frame cameras. For crop sensor cameras, multiply these field-of-view angles by the crop factor (for focal lengths longer than about 20mm). For shorter focal length lenses, the simple formula fails, and the FoV angles are a little less for the crop sensor camera.

 Figure 11.7 is another unfortunate example of carelessness. To display the image size of a person at various distances, there are ten images, each with the person at some specific distance from the camera. The caption says that “Subject distances of 5-100 feet are shown.” but the ten images presented are for subject distances of 10 ft to 100 ft!

 There is a truly bizarre error on p 156: “The front surface of any lens at its periphery is naturally more curved than its centre, which is nearly flat.” No! Almost all lens surfaces are parts of spheres, which have constant curvature everywhere. A few lenses are made with non-spherical elements; these are often towards the rear of the lens assembly, and often are (very slightly) flatter at the periphery than the middle.

 Many writers (including Swan) recommend stopping down a lens from wide-open, to reduce the effects of optical aberrations. While this makes good sense, stopping down by 2-stops as Swan recommends reduces the lens opening to ½ diameter, or ¼ area. To compensate, 4x exposure time is required (this may not be practical unless you can track your target), or else you lose 1.5 magnitudes in faintest objects imaged for the same exposure time. Sometimes you just need to accept the adverse effects of lens aberrations. Changing the gain or amplification by increasing the ISO is another option, but this can lead to noise problems, unless carefully managed. (Note, increasing the ISO doesn’t make the sensor more sensitive; it increases the amplification or gain.)

 The text on Optics of Focus (pp 161-165) is partly flawed. The notion is based around the concept of having very distant (effectively infinite distance) astronomical subjects and nearby landscape features in sharp focus. This can’t be done in an exact way, but all the various subjects of interest might be made “sharp enough” if the lens is set at some intermediate focus point. The criterion is the Circle of Confusion or CoC, where details are a little blurry, but not too blurry (what you would like be an infinitesimal dot is actually a tiny blob). Swan’s mathematics is based on the incorrect notion of getting the CoC as small as the sensor’s . This is usually unrealistic. Typical CoC values are ~20 μm, whereas pixels are typically ~4 - ~6 μm across. Getting a -sized CoC is unrealistic. After introducing the notion of achieving a pixel-sized CoC, Swan seems to abandon this goal, and recommends two related methods of setting the lens focus. Both use apps. One method involves setting the focus on the stars, by eye in the field, then checking in the app that the nearest objects of interest are further away than the near-focus distance indicated by the app. (The near-focus distance depends on various parameters you set: lens focal length, f-stop etc). The other method uses the hyperfocal distance. Under any combination of lens settings, the focus can be set to a range of positions, with the distant (“infinity”) subjects acceptably sharp. The lens setting where the distant subjects are right at the acceptable limit of sharpness corresponds to a distance called the hyperfocal distance. Subjects at the hyperfocal distance are sharpest, infinite-distance subjects (the stars) are just barely acceptably-sharp, and nearby objects at half the hyperfocal distance are also just barely acceptably-sharp. All objects further away than half-hyperfocal distance will be acceptably sharp. The hyperfocal distance can be determined also by an app. The field procedure is: measure the distance to the nearest subject you want to be sharp; double that distance is the hyperfocal distance; adjust the lens to this value, and all subjects out to infinity (stars etc) will be in acceptable focus. Swan includes such a diagram (Figure 11.14) and a table (Table 11.2). This table works for a CoC of 30 μm; so-much for matching CoC to pixel-size (~4-~6 μm)! Swan drops this pixel-matching notion without using it. One wonders why he included this dead-end track in the book. The practical advice about setting hyperfocal distance using an app is quite valuable. The f-stop setting is a compromise; the aperture may be too small to image the details you want to include (because they are too faint). A larger opening may be needed to capture faint details, but this will blur the focus.

 On p 165 Swan eventually falls into the crop sensor trap, under Lens Selection. His intention is to suggest which lenses are especially useful to photograph which subjects. He refers to “...focal length specifications (are) for full-frame cameras. These focal lengths should be reduced by a factor of approximately one-third for crop sensor cameras for the purposes of comparison.” And “Thus, a 35 mm lens would be the equivalent of a 24 mm lens on a crop sensor camera.” No; the lenses aren’t equivalent, their fields of view are similar: a 35mm lens on a full-frame camera covers 54.4° x 37.8°, a 24 mm lens covers 52.0° x 36.0° on a 1.5 crop sensor camera; i e similar FoVs, but not equivalent optical systems. Other aspects are different: for example, for both lenses at f-2, the 35 mm lens opening has a diameter of 17.5 mm, the 24 mm lens opening is 12 mm across, the area ratio is 2.13; other things being equal, the 35 mm lens will capture stars about 0.8 magnitude fainter.

 Chapter 12 (Exposure) is a failure. The subject matter is a little difficult; unfortunately Swan tries to simplify it with a wholly inappropriate analogy using fireflies. Light/fireflies emitted from the scene is/are subdivided upon entering the camera into three buckets; one for Aperture, one for , and one for ISO. The more fireflies in any one bucket, the fewer in the other two. Pointless!

 Aperture (pp 180-181) is reasonable. Swan’s recommendation to stop down by 2 stops would increase shutter time four-fold, and you might run into trailing of the stars, or lose the faintest stars you want to capture. Figure 12.4 on p 181 illustrates the nature of the compromise.

 Shutter Speed (pp 182-183) is flawed (and clumsy). Swan focuses on the desirability of keeping the exposure short enough to avoid trailing of the stars, and starts by introducing the Rule of 400/500/600. He sensibly recommends using 400 as a conservative parameter. Then all falls apart: “...for users with crop sensor cameras, you will need to multiply the lens focal length by the crop factor... to arrive at the correct focal length...” The lens doesn’t have the incorrect focal length when it’s on a crop sensor camera, so applying the crop factor doesn’t “correct” anything. How can the lens have an incorrect focal length especially if it’s been designed for the crop sensor camera? Swan has been led astray by the woolly thinking associated with the crop factor. The trail length depends on the exposure time, the cosine of the Declination of the subject, and the focal length of the lens. Changing the sensor behind the lens doesn’t alter the lens in any way. The crop sensor is irrelevant to star trailing. Finally, explanation of shorter trails associated with cos(Dec) is very clumsy; Swan seems to be avoiding expressions as complicated as simple trigonometric functions.

 ISO (pp 182 & 184) is almost as bad. “The ISO setting refers to the overall sensitivity of the camera...” At least Swan doesn’t claim that changing the ISO changes the sensitivity of the sensor. Changing the ISO changes the gain or amplification of the (invariant) sensor. Then he goes back to the silly firefly analogy.

 Selecting ISO, Aperture, and Shutter Speed for Optimum Image Quality (pp 185-187). This is the best part of Chapter 12. Swan’s advice is very appropriate. Set the exposure parameters to best address the requirements of each image. If necessary take a few test exposures, varying the parameters to test the results. For example, the aurora moves rapidly, so keep the exposure short, and adjust aperture and ISO to suit. A few details are worth commenting upon. The text warns against excess noise when using high ISO, but the example images show that the problem is not so bad. Also, one set of three images was taken to illustrate the effects of changing the ISO (Figure 12.9). The caption says that the three ISO values used were 12800, 1600, and 200 (3EV steps between each); however the images are labelled ISO 12800, 1600, and 800.

 The final part of the chapter is Expose to the Right (ETTR) on pp 187. This is a bit of a fish out of water in astrophotography. ETTR is derived from conventional day-time photography where there is plenty of light available. If a scene is underexposed, then the dark areas of the scene may not have put enough photons on the sensor to record properly. This situation cannot be corrected in post-processing. As a preventative, many photographers recommend giving extra exposure, which can be corrected at post-processing. The phrase “Expose to the Right” refers to the exposure histogram which is moved towards the right (greater exposure). However, in astrophotographic situations where the light is very dim, there may not be enough light to ETTR, and the histogram may be irretrievably stuck to the left.

 Light painting (Chapter 13 Light Painting and Light Drawing) is lighting the foreground artificially to make it visible, more visible, or even obvious. Many photographers like it; others hate its artificiality. There is also the scenario of incompatibility amongst various photographers in the field simultaneously trying to photograph something, such as a gibbous moon through a natural rock arch. Each photographer might regard the others’ light painting as light pollution. Light drawing is just fun while holding a light, such as children would do with sparklers on Guy Fawkes Night.

 There is not much in Chapter 14 (Video, Time Lapse, and Motion Production), because most of the action happens in post-production (elsewhere); but there is one gem: Table 14.1; which lists suitable shooting intervals for various subjects (naturally, the exposure time must be less than the shooting interval).

 The suggestion to stabilize the tripod using a weighted bag (p 201) is a good one, but this can be done badly. Such a bag has a larger surface area than the tripod and photographic gear mounted on it, so it can act as a sail to wobble the set-up in any breeze. To avoid this problem, let the bag be partially supported by hanging from the tripod, and partially by resting on the ground, so that it can’t swing around in the wind. Note that many astrophotography authorities recommend securing any cables and camera neck-straps so they don’t sway in the wind; a weighted bag has much more surface area and inertia than neck straps and cables.

 Extra battery power (p 201) can be supplied by a battery grip (which typically hold two of the normal camera batteries, to give approximately double battery life), or by external power supply systems. You can change the batteries in a battery grip one at a time; the camera will run on the other battery, so there will be no electrical interruption, but there is a mechanical disturbance when you swap-over batteries. Most of the external systems use a battery-shaped plug that goes into the camera’s battery compartment, (most cameras have a small rubber plug that folds out of the way to let the power cable pass into the battery compartment), and the external power source that can be a large-capacity battery that will last for several hours. The external battery can be changed-over without touching the photographic set-up, so any mechanical disturbance is eliminated. A few systems incorporate what is in effect a UPS (Uninterruptible Power Supply) that supplies power during battery changes. These UPS units usually have their own battery with a capacity comparable with the standard camera battery, and an indicator light that warns when the main “upstream” battery is running low, so that any battery changes can be done in timely fashion. Both electrical interruption and mechanical disturbance are eliminated in such a system.

 Chapter 15 (The 25 Best Landscape Astrophotography Targets) shows example images, and a brief summary of useful techniques/conditions/settings, all on one page (including half-page image) per target. One setting covered is “Aperture”; confusingly, Shaw sometimes uses other times “minimum” (i e smallest f-number, or wide open), and “wide open” interchangeably. For some targets, exposure times per the “500 Rule” are suggested, but this is a maximum; 200 or 300 Rule may be better.

 Shaw gives the start time for as early civil twilight. It really starts before sunset. You can choose to include or avoid sunlit peaks in your photos.

 For the Blue Hour, Shaw gives sunset to end of astronomical twilight. This is about 1½ hours; too long. Different people give different definitions... from 10 minutes to 30 minutes depending on whether the definition uses light conditions or angular depression of the sun. Most people would see Blue Hour as part of civil twilight time.

 For Cityscapes, Shaw’s suggestion is “Golden hour (sunset)” to “Golden hour (sunrise)”. As for Blue hour, there are various definitions for Golden hour, with different start and end points. Most people would give a start time before sunset. Actually, cityscapes can be taken anytime during the 24 hours.

 For Crescent Moon and Full Moon the exposure time suggested is “Adjust as needed”. Unfortunately appropriate exposure information is difficult to find. At ISO 100, settings near f/8 and 1/60th second should work for the Crescent Moon; and for Full Moon somewhere around ISO 100, f/8 and 1/500th second should work. The surface of the moon is dark grey (maria) and mid grey (lunar highlands); full moon is sunlit grey rock, so a full moon photo should be exposed like a daylight photo, even if the time is after astronomical twilight ends.

 For Meteor/Meteor Shower Shaw recommends exposure time according to the “500 Rule” to avoid star trails. An alternative approach is to use a longer exposure, and accept star trails. Also, longer exposures have a greater chance of capturing meteors.

 For Zodiacal Light the start/end times given are wrong. Shaw’s writes that it is after the end of astronomical twilight in the evening. The sky is sufficiently dark at the beginning of nautical twilight to see and image Zodiacal Light, and it fades away often during late astronomical twilight. Maybe that’s why Shaw regards Zodiacal Light as rare (p 90); has he tried to see/image it after it’s faded away?

 Chapter 16 (Developing your Astrophotography Session Plan) is quite good.

 Likewise Channel 17 (Essential Software and Apps) is also good. However, as in all things software, it is liable to going out of date. One important thing to keep in mind is that any mobile app that uses the sky in Augmented Reality needs an appropriately sophisticated mobile phone, one that senses its orientation in three dimensions.

 There are a few things to think about in Chapter 18 (Essential Hardware and Equipment). Many headlamps have an annoying cycle of modes: steady-red/steady- white/flashing-red, if you want steady-red twice in a row, you need to cycle through the other two modes to get back to steady-red. Others cycle through a few different levels of brightness. What you need is a simple single-mode red lamp; this can be difficult to find, and more expensive than the mode-cycling headlamps.

 On p 274 Shaw mentions the use of a circular polarising filter to enhance twilight clouds, enhance rainbows and moonbows etc. The linear polarising filter also has a use. The Zodiacal Light (and other glows in the sky such as Kordylewsky Clouds) is formed by reflection of sunlight off interplanetary dust; images taken with no polariser, compared with polariser parallel to the ecliptic vs polariser at 90° to the ecliptic should reveal this polarisation state.

 The FLW filter referred to on p 278 and Fig 18.8 is more properly the FL-W filter (FL for fluorescent, W for warm-white). Warm-white tube-style fluorescent lights emit strongly in green (i e near the middle of the visible spectrum); the purple of the FL-W light counteracts this green colour cast by emphasising the “ends” of the spectrum (blue + red = purple) when using daylight film under fluorescent lighting. (Suppose your camera was loaded with a roll of daylight film but you were caught-out by needing to take photos indoors under fluorescent lighting.) This use of the FL-W filter is virtually obsolete; with modern digital cameras, the fluorescent light colour- cast can be either prevented using the appropriate camera setting, or corrected in post-processing. A new-found use is to enhance twilight photos by inducing a purple colour, while the camera remains set to daylight (or auto) colour-balance.

 Chapter 19 (The Landscape Astrophotography Clinic) of Section V (Creating Landscape Astrophotography Images) begins by emphasising the importance of daytime reconnaissance of the proposed imaging location. One vital point not mentioned by Shaw is the presence or absence of foreground trees that will obscure the sky or distant features in the landscape. This is especially important in protected locations like National Parks, where trees aren’t cleared.

 The bulk of Chapter 19 illustrates the daytime pre-visualising available if you use PhotoPills Augmented Reality feature. This feature projects night sky (Milky Way) views saved from pre-modelled scenarios onto the live view of the landscape seen via your Smartphone’s camera. This feature is available to upper-range phones with Android operating systems and internal accelerometers that “know” which way the phone is facing. GPS location mode needs to be activated too.

 A misleading statement on p 296 in Chapter 20 (Obstacles and Common Unexpected Problems) deserves comment. Under the general notion of the inexorable movement of objects across the sky, Shaw comments that the Sun takes a surprisingly short time to set after first touching the horizon, and the Moon even less. The Earth-Sun distance varies by ~3.3% ([aphelion-perihelion]/aphelion) during a full orbit, and the angular width of the Sun varies from 31′27″ to 32′32″, whereas the Moon’s orbit is more eccentric, and the distance varies by ~10.6%, so its angular width varies from 29′20″ to 34′6″. So, sometimes the Moon looks smaller (when it’s in more distant parts of its orbit) and takes a little less time to set, and sometimes it takes a little more time when it is closer and wider. The difference is not noticeable in the context of how responsive you need to be to capture an image. Naturally, when the moon isn’t full (rather, gibbous or crescent) the illuminated portion has a smaller angular size and will disappear more quickly at moonset.

 One hidden gem in Chapter 20 sits on p 299. Under “Memory Cards and Batteries” (mainly a reminder to have several spares of each handy as back-ups), Shaw advises never to touch the gold terminals of the memory card, lest a static discharge corrupt the data on the card. I’ve never seen anyone else mention this.

 On p 301 Shaw mentions something potentially confusing; the chemical reaction that generates electrical energy in the camera battery slows as the ambient temperature falls; “This reduced output is manifested as a shortened battery life.” It’s not the battery life that shortens, rather the length of time that the battery charge will last. Shaw recommends warming camera batteries to make the charge last longer, even to attaching hand-warmers to the camera body. Unfortunately, one form of “noise” in the image is thermally-generated, typically doubling for a 7 C° rise. Warming the battery in-camera is incompatible with keeping the sensor cool to reduce thermal noise.

 Shaw gives advice on cleaning lenses etc on pp 300-302. Like most photographers his warnings about the potential to damage your lenses during cleaning are exaggerated. As any wearer of spectacles knows, image degradation by “dirt” can be severe; any damage caused by cleaning usually can’t be detected. (And spectacle- wearers clean their glasses much more often than photographers clean their lenses.) The best guideline is: avoid getting the lens dirty, and then clean it carefully when necessary. Shaw’s cleaning technique is sound.

 The UV-filter that many people use to “protect” the lens is part of the optical system, and must be kept as clean as the lens. Because the filter is ahead of the lens, it is nearer to being in focus (especially for short focal-length lenses), so a dirty filter is worse than a dirty lens. Many films are/were rather sensitive to near-visual UV light (which behaved as blue light), and a filter was appropriate to mitigate this sensitivity issue. Modern sensors are less sensitive to UV than film was, so specific UV filters aren’t so useful any more. These days they are sold to “protect” lenses; but this is controversial, because filters are more fragile than lenses. Drop tests of lenses with UV filters mounted found the following: if the shock isn’t too severe, only the filter is broken and the lens is undamaged; more-severe impacts damage the lens mechanism, misalign the glass elements, and degrade the optical performance by misalignment. It takes a severe impact to break lens elements. Lens caps offer better protection against impact and dust than filters. Lens hood also offer some protection against impact. If you use a UV filter, it ought to be a high-quality item; and price is not an absolute guarantee of quality.

 Section VI (Processing Landscape Astrophotography Images) is split into two Chapters; 21 (Image Management and Processing Foundations), which concentrates on processes applied to either single images, or identically to a batch of several images; and Chapter 22 (Creative Nightscapes: multiple Image Processing) which deals with combining multiple images that are different from each other in some way. This Section is a brief introduction to some of the processes available in Adobe Lightroom and Photoshop), not a replacement for the instruction manuals, or other resources such as YouTube video tutorials. Shaw usefully separates the Lightroom processes from the Photoshop procedures, in case you have Lightroom, but have not lashed out on Photoshop.

 Multiple-image processing examples in Chapter 22 (mostly using Photoshop rather than Lightroom) include the following: Blending an image that has a bright twilight sky and a dim (underexposed) foreground, with another image of the same scene where the foreground is attractively bright but the sky is washed-out (over-exposed); the aim being to combine the “nice” sky of one image with the “nice” foreground of the other, to produce a third image that is “nice” everywhere. Dark-frame subtraction, and stacking of multiple sub-frames are also mentioned (rather than explained in detail). High Dynamic Range (HDR) processing to extend the dynamic range of a scene is also touched upon; a few images of the same scene are made, each with a different exposure, and combined so that all the bright (“over-exposed”) details and all the dim (“under-exposed”) details are well-separated in tone on the final image. Focus-stacking is another example mentioned, in which (usually two) images are made of the same scene; one focussed sharply on the sky, the other sharply focussed on details of the foreground; and the sharp parts of the two or more images are blended to yield a final image that is sharp everywhere. Focus issues are common in astrophotography, because the lens is used wide-open or nearly-so, where depth-of-field is shallow. When the foreground details have been light-painted, and a combination of bright artificial light, short shutter time and low ISO has was used; this image must be blended with a longer-exposure higher ISO sky image with prominent noise that is most visible in the dark foreground. The shorter exposure results in less noise, including the dark (non-light-painted) parts of the landscape. Shaw calls this ISO blending. For longer-exposure tracked sky images, the foreground will show movement-blur; to eliminate this issue, take a stationary photo exposed for the foreground, and blend it with the tracked sky image. One of the trickiest scenarios Shaw treats is making panoramas. This procedure is valuable when you lack a super-wide-angle lens, or you want high resolution, or seek to “reach-down” to faint stars. The magnitude of the faintest stars reached depends on the area of the lens (proportional to [diameter]²); but a large area lens will have a longer focal length, and this will limit its angular coverage. You can get more angular coverage by stitching together a number of adjacent images, but you need a moderate overlap between them, so there are enough details in common for each pair of the images. Before stitching the images together you should correct for light fall-off (often wrongly called – true vignetting is physical obstruction caused by a too-small circular opening somewhere in the light-path) towards the corners of each image, and reduce or correct excessive distortion of each image. Another example in Chapter 22 concerns assembling images of star trails. A single long exposure (many minutes, to a few hours) would allow the sky brightness to rise to unacceptable levels; the work-around is to take shorter fixed-tripod exposures in succession (with minimal delay between each image), then link the short trails together (using appropriate software) to a more desirable total arc length. Incidentally, Figure 22.11 is the best explanation I have seen of the notion of “interval” during a succession of images; for some (most?) manufacturers of intervalometers, the “interval” is the cycle time-length (gap = interval – image- duration), others call the gap between images the “interval”. There must be sufficient time between exposures to write each image to the memory card. One- second is usually enough. On pp 351-353 Shaw goes into a detailed explanation of the differences (and benefits) of longer single exposures vs stacks of shorter ones. While this analysis is valid elsewhere, it is irrelevant here; the star-trail segments are not added over each other, but tacked together end-to-end. The penultimate scenario that Shaw considers in this chapter is stacking individual meteors from a number of images captured during a meteor shower.

 Unfortunately, the final scenario in Chapter 22 (time–lapse video) is rather poorly handled. One flaw common in time-lapse is called flicker, which is sudden minor brightening and dimming of the video clip. Shaw’s explanation of the cause is wrong; he writes that the diaphragm blades for each exposure open to slightly different positions, giving slightly different exposures; but you still get flicker if you use an old (1970s) manual lens with a diaphragm that the camera doesn’t adjust. There are two main causes: if the camera is used in a mode which adjusts the exposure (auto, shutter-priority, aperture-priority, or “program”), it cannot adjust exposure more finely than ⅓-stop, so if the camera “decides” the scene needs more exposure, it will jump up ⅓-stop, overshooting optimum exposure, then reduce exposure by ⅓-stop for the next image, undershoot etc. A second cause is variations in the scene’s contents, as clouds enter and pass across the view, as bushes and tree limbs wave in the breeze, and (for cityscapes) as vehicles and people move about. The camera adjusts exposure to compensate for these variations in scene content. Another problem with this sceario is the term “Holy Grail”, which Shaw merely mentions; but he fails to explain that the “Holy Grail” is getting a properly exposed time-lapse sequence from sunset to dark (or dark to sunrise).

 Shaw seeks to draw the reader’s attention to useful solution strategies, rather than providing “recipes”. Note that Photoshop is a “Jack-of-all-Trades”; there are other dedicated programs (many of them low-cost or free) that solve each of the scenarios in Chapter 22, many of them better than Photoshop does.

 One of the best features in the book is Chapter 23 (From Concept to Curating – Four Detailed Case Studies), part of Section VII (Detailed Case Studies). Shaw works through the planning in detail, then the execution, and gives a few comments on the post-processing steps for four case studies. The first case study (Orion over Mount Whitney and through Möbius Arch) contains a couple of slip-ups. On p 364, Shaw refers to Mt Whitney (14 505 ft) as the tallest mountain on the continental United States. Not so; Alaska’s Mt Denali (20, 146 ft) is the highest in the continental U S; Mt Whitney is the highest in the 48 contiguous States. The second mistake crops up in the timetable Shaw used to set up on-time at Möbius Arch. On p 365 he summarises hiking-in time and set-up time to determine the best departure time from the trailhead as 4:00 am. He repeats the timetable on p 369, but wrongly gives the target time to arrive at the trailhead as 5 am. This should be either: arrive at the trailhead before 4:00 am, or leave the trailhead by 4:00 am (to begin the estimated 20-minute hike-in), or arrive at Möbius Arch by 4:30 am (to allow an estimated 1- hour set-up time for imaging to start between ~5:30 and ~5:45 am).

 The second case study (Supermoon over Mount Whitney) repeats the “...tallest mountain in the continental U. S...” error, this time on p 372 in the text, and in the caption of Figure 23.6. Shaw emphasises the rarity of the Supermoon (Full Moon coinciding with perigee). (There is too much fuss over the Supermoon; the angular size at apogee is 86% of the angular size at perigee. Perhaps people confuse the Supermoon with the Moon Illusion. When the Supermoon is rising near sunset, there is simultaneously the condition for the Moon Illusion; wherein a Full Moon close to the horizon is perceived as huge, much larger than when it is tens of degrees above the horizon.) Full Moon is an instant, as is perigee, so exact coincidence is indeed rare; but the Moon is considered “Full” for about three consecutive days; and its angular width varies little from day to day, so it can be considered “full-size” for a few days around perigee. The average length of synodic month (full to full) is 29.53 days, whereas the anomalistic month (perigee to perigee) is 27.55 days. If there is a Supermoon on some particular date, then at the next full moon, it will be two days past perigee, but will look like a Supermoon anyway. A similar situation exists for one full moon earlier. So, true Supermoons are rare, but if the criterion is relaxed a little, “near-Supermoons” occur in threes or fours about 14-15 months apart. (Fourteen synodic months approximates fifteen anomalistic months.) In summary, there are usually about three instances of a near-Supermoon per year. Of course, to make an optimal composition for an attractive image, other conditions need to be satisfied: sky colour appropriate to the stage of twilight, moon placed “just right” compared with features in the landscape, absence of clouds etc. The ideal coincidence of all the parameters may repeat only after a few years.

 Detailed pre-planning can be quite tricky... The angular width of the Full Moon averages about 30’ (~½°). At this angular size, a foreground object appears to move sideways one moon-diameter if you move sideways only 0.009 of the distance to the foreground object. As a practical example, if you want to photograph the rising Full Moon sitting on a peak 5 km away, and you are about 22 m off-line (5000-m X 0.009 X ½), then the side of the moon rather than the middle will sit above the peak. The sky rotates 1° in 4 minutes; the Moon with its ½° width rises fully in 2 minutes. So if you were 22 m off-line, you have only 2 minutes (from first peep of the rising Moon to Moon fully-risen) to move 22 m and set-up in the new spot. In rugged country, sea-level moonrise/set is irrelevant; you need time/azimuth data at expected angular elevation. Photographing a setting Supermoon around is easier, because you can watch the sinking Moon approach the ideal spot in the sky, with a bit more warning. Exposure for imaging a low Supermoon is easier one day before Full Moon, when the sun is in the sky, and is illuminating both the Moon and Earth. One day later, when the Full Moon rises 20-60 minutes later, the sun will have set, you will be well into twilight, the foreground will be darker, and matching the bright Moon to the dim foreground will be more difficult. Note that it is difficult to measure bearings to better than 1° with a compass, or read a map bearing with a protractor to better than 1°. A more-accurate approach is to use software such as PhotoPills (or The Photographer’s Ephemeris), which predicts moon azimuth to 0.1°, and mapping software such as Google Earth that allows bearings between points (foreground landmarks and camera points) to be read to similar precision (actually, to 0.01°).

 Shaw failed on his first attempt (6th May 2012) in this Supermoon case study, because he used sea-level moonset and sunrise times. When the moon was in the right position, the time was so much earlier than sunrise that the mountains were too dark. On the following dawn (7th May 2012), moonset was 56 minutes later, and the sun was shining on both the Moon and Mt Whitney; the exposure was quite straightforward.

 The third case study (Star Trails over Split Rock Lighthouse) is well-presented.

 The fourth case study (Milky Way over Chumash ‘Ap) was made at a re-created native American village. (The Chumesh inhabited southern and central coastal California; ‘ap is their word for a traditional house). This case study was done before Shaw fully realised the value of prior daytime scouting and pre-estimation of camera/lens settings; and shows how the Milky Way inexorably marched across the sky while he was scouting the site on the night of imaging.

What Shouldn’t Have Been Left Out

This is not extra topics that I would like to see; it’s where Shaw has been light-on in what he has covered. My opinion, but I think this stuff should have been included:

 Information on tracking mounts. There is a small amount (p 203) on using tracking mounts as panning units for time lapse sequences, rather than as star-trackers.

 Websites that forecast weather, especially those that include aspects relevant to astronomy:  Meteoblue - https://www.meteoblue.com/  Clear Outside - https://clearoutside.com/forecast/  Yr (Norwegian Meteorological Institute) - https://www.yr.no/place/Australia/Queensland/

 Choosing lenses for imaging meteor showers. This is tricky; first thought might be for the widest-angle lens you can get/afford/own. However, super-wide-angle lenses have very short focal lengths, and therefore small diameters that don’t collect much light (for example a 10 mm f2.8 lens is only 3.6mm wide; a 50 mm f 1.8 lens is 27.7 mm wide; the area ratio, and brightness ratio is 60.5. This is worth ~4.5 magnitudes of fainter meteors). The exposure time before trailing becomes visible in the 50mm case is ⅕ the exposure time for the 10 mm lens situation. You need either to use a tracking mount, or accept substantial trails. There is an extra problem with meteor photography in general. Meteors rarely glow for more than 5 seconds, and with vanishingly-rare exceptions, the meteor image flashes across many pixels rather than sitting on one pixel for the duration.

 Information on post-processing. The details on capturing images are pitched towards the less- experienced photographer; but the lack of detail on processing captured images is more consistent with a seasoned user of processing software, particularly Lightroom and Photoshop.

Alternatives to this Book

A lot of good heavy-duty stuff has been written by Roger Clark, about all manner of things: sensors, image processing, DSLR astrophotography, signal-to-noise ratio mathematics (including the statistics). It’s free on his website: https://clarkvision.com/. He is at odds with some of the other “gurus”, but what he says makes a lot of sense to me.

For a YouTube approach aimed at beginners, Brenda Petrella’s Milky Way Photography Series videos are good to start with: (Part 1 – How to plan a Milky Way photo; Part 2 - How to prepare for night photography; and Part 3 – How to photograph the Milky Way). These are well-presented, and free of mistakes. She has a background in molecular biology and biosafety, and like Mike Shaw, left a scientific career to become a full-time photographer. See her website: https://www.brendapetrella.com/

There is also Phil Hart’s ebook: Shooting Stars; How to Photograph the Moon and Stars with your DSLR, available from his website http://philhart.com/ for $14.95 USD (about $23.09 AUD).

Summary

Shaw’s book is quite good, but could have (and should have) been better, without adding significantly to the cost of production, or cost to the retail customer. I don’t think I would buy a copy, but I certainly would recommend borrowing it from the SAS Library.

Bill D’Arcy,

13 Nov 2019.