Tilt-Shift Photography
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Makeit Tilt-shift photography Julian Bucknall explains how special lenses and clever post-processing create distinctive effects hen I go on holiday, simple affair comprising two What’s covered I always take pictures standards or planes – one Distributions W of buildings in the holding the fi lm plate (and a PHOTOGRAPHIC places I visit. It doesn’t matter ground glass viewfi nder) and The random numbers your programming language run-time EFFECTS where I travel to, there’s always the other holding the lens. In produces come from a linear (or In modern point-and-shoot and some beautiful architecture between the two was a bellows uniform) distribution: all values DSLR cameras, the axis of the lens just waiting to be appreciated that didn’t let in light. The are equally likely to be produced. is fi xed. If you allow the lens to and photographed. standards were mounted on Sometimes you need random be shifted or tilted you can numbers from other distributions, achieve some quite clever eff ects, The problem is, to get a one or more rails so they could such as exponential, or Poisson, like taking photos of buildings whole building in a shot, you be moved closer to or further or Gaussian. The Gaussian (or without converging verticals, or either have to move further from each other to focus the normal) distribution is important creating landscape photos that look away than you’d like, or point image, and to provide other in statistics. The heights of men like shots of scale models. You don’t of the same age in a population need specialised equipment though the camera upwards in an options like perspective and follows a normal distribution. – some of the neater eff ects can effort to get the top in as well depth of fi eld. Figure 1 (p73) Asking a group of people to be done in your favourite photo as the bottom. When you do illustrates the basic setup. measure something with a ruler processing program. Find out how. the latter, the verticals in the Notice that the image is seen will produce values that follow a normal distribution, and so on. photo converge upwards and upside down in the viewfi nder. There is a standard algorithm the building appears narrower DSLRs reverse the image so called the Box-Muller method to at the top than at the bottom. that the view you see through generate random numbers that One solution to this issue the viewfi nder is the same follow the distribution, but taking our cue from the Gaussian blur is to use a wide-angle lens, way up as the real view. trick, a simpler method is to but this isn’t without its own generate six uniform random problems: this type of lens will Rise and fall numbers and take their average. tend to include more of the Since the bellows were The resulting averages follow a normal distribution. foreground, even as it provides fl exible and the lens and fi lm a better shot of the building. standards were separate, these The better answer is to use view cameras could provide a (known as rise and fall), or either a view camera or a whole set of effects that are moved from side to side (the tilt-shift lens on a DSLR. hard to produce with modern traditional shift), all while Back in the very early days point-and-shoots or DSLRs. keeping it in the same plane. of photography (and even The fi rst of these were Modern tilt-shift lenses on today with specialist cameras), shift movements. The lens DSLRs provide much of the the camera itself was a very could be raised or lowered same functionality, but they are specialised pieces of equipment and are generally very expensive compared to normal prime or zoom lenses. Spotlight on... Threshold blur The rise movement on a A Gaussian blur attemps to is in the portrait photo industry: of the edge are averaged with view camera is important for recreate the eff ect of viewing a blemishes are easily removed by similar pixels on their particular architectural photography. To photograph through a ground this digital process without the side), but in between the edges properly use the rise shift, the glass screen. The blur may be resulting image looking too the pixels get smoothed out since image circle of the lens must symmetric and pleasing, but it ‘Photoshopped’ and blurry. they are surrounded by similar be larger than the rectangle doesn’t preserve the edges in This works by applying the pixels. Blemishes are therefore covered by the fi lm. The image the photo; those get blurred standard box blur (or Gaussian removed without losing the circle is the area of the fi lm and smoothed out along with blur), but only using those pixels sharpness of the edges. plane formed by the cone of everything else. in the box that are similar in value Tweaks to the blur include light that comes through the Sometimes you’d to preserve (similar to within a threshold the threshold value (the bigger lens. The majority of the image those sharp edges, but blur areas value, hence the name of the the threshold the stronger the circle is masked off, leaving of the photo that look roughly blur) to the central pixel. Edges smoothing action) and the radius just a rectangle that exposes similar. The best example of this are preserved (since both sides of the underlying Gaussian blur. the sensor of the camera (or the frame of fi lm). If the 72 321 May 2012 www.pcplus.co.uk PCP321.theory.indd 72 3/27/12 4:40:32 PM Tilt-shift photography Make it – also tilts (geometrically it intersects the previous two at the same position). In fact, by varying the tilt, you can bring nearer and farther parts of the view into focus at the same time (the effect on Figure 3 would be to bring all of the text into focus). Notice though that this is not the same as increasing the depth of fi eld by reducing the size of the aperture; this is a totally different effect, although a Tilt-shift photography photographer can balance the need for smaller apertures to increase the depth of fi eld by using a tilt movement. Model behaviour Tilt movements are used in two contexts: landscape photography where you would prefer having more of the view ▼ Figure 1: The basic schematic of a view camera in focus, and diorama effects. The diorama effect is a camera’s lens is shifted, a (just try that in the National the more obvious this sharp process that converts a different part of the light cone Portrait Gallery). Another is focus plane is. In Figure 3, photograph of an ordinary exposes the sensor or fi lm to photograph the painting I took a photo of the word ‘tilt’ view into one that looks like frame. If the image circle is from a slight angle, making in the Oxford Modern English it was taken of a scale model. small enough, the fi lm frame sure that the incident light is Dictionary at an angle with Figure 4 shows this effect on will not be fully exposed to the behind you so that refl ections the aperture wide open to a line of beach huts, and you light and you will get the effect go away from the camera, illustrate the focus plane. may also have noticed the known as vignetting, where and then fi x the perspective in There are four planes here: the diorama effect in the titles for the photo fades and darkens your favourite photo editing plane of the sensor, the plane the BBC TV series Sherlock. towards the edges and corners. program (Photoshop has of the lens, the focus plane The reason this effect works Figure 2 shows what such a feature). Alternatively, (which is parallel to the fi rst is that, through exposure to happens with rise shift. In you can use a left/right shift two), and the plane of the page photos of miniature scenes the fi rst image (I’ve fl ipped movement to remove the in the book (at an extreme and landscapes, we know how the view so we’re not looking refl ection of the camera using angle, almost perpendicular to the depth of fi eld operates at it upside down), we see the the same technique as for the fi rst three planes). Notice for small scenes versus large normal state of affairs: the architectural photography. how the focus tapers off scenes. For miniatures, the image circle encompassing quickly the further or closer depth of fi eld is very shallow, the fi lm frame with the top Tilts and swings the text is to the camera. even at small apertures. of the building cut off. The The other main set of possible With a tilt movement, the This means that, even with foreground is also prominent. movements with a view lens is tilted up or down with small distances closer to or The second image shows the camera are called tilts and respect to the fi lm plane – further away from the camera, effect of the rise shift: the fi lm swings, known collectively as they are no longer parallel. the depth of fi eld falls off frame is in the same place tilt. In normal use, the axis The plane of the lens now dramatically. Take a look at (we’re moving the lens up and of the lens is perpendicular to intersects the plane of the fi lm Figure 3 again to see the down, not the fi lm standard), the plane of the fi lm or sensor.