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Home , Analog photography, Photographic film, Slide projector

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by Dr. Chris Lantz

Many publishers have routinely relied on for low resolution applications in newspaper production and desktop publishing for just over a decade. that capture just beyond television resolution images (640×480 ) are adequate for some of these applications and typically cost $300–$1,000 today. Low- resolution digital cameras are well suited to web sites, computer presentations, and output to laser printers because their resolution capacity matches the typical output resolution of low-cost monitors and printers. Higher resolution megapixel cameras have recently been introduced at slightly under $1,000 for the first time. These new low-cost cameras complement the increasingly common 1152×780 computer display resolution and desktop resolu- tions above 600 dots per inch (dpi). The future widespread adop- tion of the Federal Communications Commission approved HDTV (High Definition TeleVision) standard will likely spark a new round of low cost digital cameras to fill an even higher resolu- tion standard in the near future. At the upper end of the digital market, commercial publishers have used high resolution digital cameras for catalogs and periodicals which depend on the rapid production of hundreds of images per issue. Currently, there are high resolution cameras in the $10,000–$20,000 price range that can approximate the resolution of ISO 400 speed 35mm trans- parency . There are also cameras in the higher $25,000– $50,000 price range that can approach the resolution of conven- tional such as ISO 25 speed 35mm transparency film. Some imaging can now exceed the resolution of 4×5 or 8×10 inch film, but these currently are only cost effective for applications such as remote imaging via satellites.

Visual Communications Journal 1999 Page 19 Even though the quality of images that can be produced by digital cameras has increased dramatically in the past few years, they may not be appropri- ate for many uses. In this , the author compares the charac- teristics of film-based cameras to the characteristics of digital cam- eras and makes recommenda- Figure 1: Bellows (left) and extension tubes (right) provide cameras an tions regarding the use of each ability to image objects larger than life size on film. The greater the dis- type of camera in today’s market. tance between and camera the closer focusing distances are possible.

Camera controls: digital versus analog ping capability are essential cre- natural , electronic ative tools of the professional lighting is unnatural by virtue of A disadvantage to many of the photographer. its angle and the high contrast of low- to mid-priced digital cam- Another drawback of the low- the shadows it casts. There are eras on the market is they rarely cost digital cameras is that they some techniques that can be used have the manual and do not have a removable lens to soften flash lighting, such as focusing controls on which pro- mount. Hundreds of convention- bouncing it off a white card, but fessional photographers depend. al 35mm SLR camera and the small built-in flash lamps Some high-end digital cameras accessories are available. Without available on digital cameras lack in the $8,000-$25,000 price access to special lenses, photo- both the power and angle adjust- range are actually film-based graphers cannot use low-cost ments to make such techniques cameras that are converted to cameras to control the angle of possible (Figure 2). digital-based cameras by replac- view and perspective of objects in Most of the lowest-cost digital ing the film back with a digital the scene. In addition, close-up cameras have fixed-focus or sensor back. These converted or is not an focus-free lenses. Fixed-focus cameras are equipped with the option when using many low- means that the lens was fixed at manual controls of the standard cost cameras, because special one focus point at the factory and 35mm camera from which they equipment, such as extension that any subject closer or further were created. tubes and bellows, is not available away from this point will be out In the $500–$3,000 price (Figure 1). of focus (Figure 3). The focus range, digital cameras do not Other big disadvantages of the point is in the middle of the lens have the control lenses on low-cost digital cam- focus range. This provides a rea- afforded by f-stops, nor the eras are their relatively low qual- sonable chance of getting a sharp motion-stopping control provid- ity and less-than-optimal light picture, but the drawbacks of ed by a manual speed. gathering ability. High-speed fixed focus are very apparent These are major limitations that lenses transmit more light when with close up photography. prevent many professional pho- needed in low lighting situations. Better digital cameras have tographers from switching to the lenses are often true auto focus mechanisms digital format. Control over quite slow, so harsh flash lighting which ensure sharp focus on sub- depth-of-field and motion stop- is necessary. When compared to jects at various distances from

Page 20 Photography for reproduction ride. Manual exposure allows photographers to produce a dark or light picture on purpose or as a special effect. Even if the pho- tographer is shooting a dark or light subject, the exposure system in an automatic camera is pro- grammed to produce an 18% gray average density. If manual exposure controls were provided, the photographer could overex- pose to compensate for a light Figure 2: The flash built into digital cameras are not adequate in power nor subject or underexpose for a dark have the angle adjustments to allow softer more natural reflected light as is subject. provided in the bounce flash setup on the right. Despite the disadvantages of low-cost cameras, they still have the camera, so long as the subject the subject is dimmer or brighter many important advantages. A is in the center of the viewfinder. than the background or if the 640×480 image can be accept- Autofocus systems have a sensor subject is not centered in the able, even in high-resolution that measures the distance to the viewfinder. Multi-cell metering magazine publishing, if it is used subject and then changes the collects light readings from vari- at a fraction of its original size. focus of the lens elements to ous positions in the viewfinder Many lower-cost cameras are just compensate for different dis- and averages the readings. Multi- starting to incorporate exposure tances. Although this is much cell metering compensates for value (EV) adjustments, which better than fixed focus, it still back-lit scenes that would turn photographers can use to adjust causes problems if the photogra- out as silhouettes without this to prevailing lighting conditions pher wishes to place the subject feature. using a built-in LCD preview of the off-center. Finally, most entry-level cam- screen (Figure 4). As digital pho- One approach to solve this prob- eras lack a manual exposure over- tography rapidly becomes more lem is to use multiple focus sen- sors across the field of view and not just in the center. This improved focus system is avail- able in conventional cameras but not for low-cost digital cameras. Low-cost digital cameras of- ten lack light metering features such as multi-cell metering and backlight control. In addition to calculating the focus from the center of the viewfinder, many cameras measure the amount of Figure 3: The Quickcam is an example of a fixed focus digital camera (left). light in the scene from the center It is possible to change the fixed focus point but the camera needs to be disas- only. This can cause problems if sembled in order to accomplish this, as is demonstrated on the right.

Visual Communications Journal 1999 Page 21 Figure 4: This digital camera has the ability to capture images on standard floppy disks (left). It also has a three inch LCD viewing screen. This screen is used as a viewfinder, to preview images, and also make exposure adjustments with a built-in EV control (right). mainstream, many of the features Basic image structure: will be much less expensive in the that are presently lacking in low- digital versus analog future. However, even the most cost cameras will be included. optimistic do not predict that When this happens, many more In spite of these rapid devel- digital imaging systems will be applications will be opened up to opments, digital imaging tech- able to financially compete with digital imaging. nology has not overtaken tradi- most film-based systems in the As recently as 1996, only a few tional photography as the stan- short term. Even if revolutionary low-cost digital cameras were dard format for many commer- imaging systems were developed available. By 1998, there were cial publishing applications. This in the short term, problems, such over 50 models. One new type of is mainly due to the fact that as projection and display of digital camera is the Digital conventional are images, will still exist. Computer Video Cassette (DVC) camera very high in resolution and low projection, LCD, and flat plasma that can be used to capture both in cost. slide panels are great recent strides still pictures and video (Figure film, invented in 1937, currently that have been made in digital 5). DVC cameras have a new costs under $10 per roll, and, image display. However, these Firewire computer interface. when scanned on a high quality devices typically provide defini- Firewire allows the direct trans- drum scanner, can exceed the tion just slightly more than twice fer of digital data from a DVC to resolution of $25,000 digital the resolution of the present-day a computer. In the past, when imaging systems. An imaging National Television Standards photos were needed from a video system that costs $25,000 today Committee standard (NTSC). A source, the computer required a specialized video capture board (Figure 6). DVC cameras allow the direct capture of individual video frames because data stor- age in the DVC and computer are both digital. No converting of analog to digital video is neces- sary. Figure 5: The digital video cassette (left) is a new video format that can interface directly with a computer with the firewire interface (right).

Page 22 Photography for reproduction conventional large-format film. In particular, black-and-white A typical 35mm slide photos have very good archival costs from $200–$500 and is characteristics because they are smaller, lighter, less fragile, high- metallic ; most deteriora- er in resolution, and more reli- tion of black-and-white plates is able than a data projector for caused by tarnish and atmos- presentation of static images. pheric conditions. Although Film recorders can record com- some CD-ROM media could puter images on 35mm slides, last just as long as black-and- Figure 6: These are the video and many presenters prefer using white photos, it is unlikely that input/output ports of a video cap- a low cost to pres- many CD-ROM drives will be ture card on the back of a computer. ent these slides as compared to around in 100 years. Film is still A video capture or digitizing card the inconvenience of setting up a less expensive than magnetic or takes input from a standard analog laptop and portable data projec- CD-ROM media to store high video source and converts it to dig- tor. resolution images. For example, ital data. Another advantage of film hospitals still store x-ray films versus digital is that images because digital images cannot typical data projector in the archived on film are far more match the resolution of a large $5,000–$10,000 price range can permanent than those recorded format x-ray without taking up produce a maximum resolution on electronic media. The project- an enormous amount of storage of 832×624, and this is at least ed life of some prints and trans- space. Many soft tissue details 100 times less resolution than parencies is well over 100 years. could be lost if x-ray images are scanned at a low-enough resolu- tion for economical archival. Even those medical imaging pro- Linear Imaging Charged Coupled Device cesses that originate from digital Output Voltage application data, such as CAT scans or NMR, are imaged on conven- tional , using a , for study and stor- age. The line of photosites So, how can such an old Silicon based convert light into chip substrate electrons which travel chemical based imaging system to the transfer gate next to it, with the voltage such as photography, invented by acting as a catalyst a fortunate discovery in the mid for the movement of electrons 1800’s and perfected in the early 1900’s, beat out the current state- The transfer gate or of-the-art digital imaging and switch transfers the electrons generated projection systems in terms of Local electrical by light to the output resolution, price, and longevity? charge detector storage device and storage The main reason is the nature of the smallest picture element or Figure 7: The basic structure and operation of a . In electronic images, these CCD or charged coupled device. are manufactured in the form of

Visual Communications Journal 1999 Page 23 Photographic image formation 1. crystal before exposure... tain a . This leaves a

Sensitivity Speck permanent silver metal image. Silver Ions (Imperfection in crystal) Light-sensitive photographic The amplification of the film is made from silver salt crys- atomic silver to a visible but ex- 2. Exposure to light produces electrons which are attracted to the sensitivity speck, tals, suspended in gelatin, that tremely minute picture element causing it to be negatively charged. Positive holes are also formed... Speck negatively are coated onto a clear polyester in the developing process is com- charged Light + - [-] Electron - . This coating is thinner parable to converting the mass of [+] Positive holes + - - - +- + - + - + - than a human hair. Each of these a golf ball into the Empire State

3. Positive holes move to the surface, sliver salt crystals is sensitive to Building. Development is in- taking the bromide reaction by-products along and neutralizing them in the gelatin + light and are created by the mix- credibly efficient and requires Silver metal latent image, + which is magnified - up to 50 billion times ing of and a halide very little light to produce an - + + - - when developed + such as bromide. A latent image image on film. Film’s ability to + The positive silver ions are attracted is defined by just a few atoms of magnify light in high-resolution to the charge at the speck. The negative electrons and positive silver silver formed by exposure to light distinguishes itself from high ions at the speck combine to form a silver metal latent image in an individual silver salt crystal. resolution digital imaging. Mag- Latent images are developed in a nification of light is possible Figure 8: Latent image formation chemical developer, which am- using digital imaging. However, and development plifies the atomic silver millions this currently leads of times, into a visible picture to a comparatively large loss of a photosite on the surface of an element (Figure 8). A photo- resolution. More light is needed imaging device, such as a charged graphic image is made perma- for higher resolution for both coupled device (CCD) (Figure nent, or fixed, by removing those film- and digital-based imagery. 7). The size of these photosites is silver salts which have not been An increase in light yields more limited to the capacity of the sil- exposed to light and do not con- resolution in film than it present- icon wafer or chip substrate material on which they are man- ufactured. Currently, whole com- puters can be put on a portion of Simplified Cross Section such a silicon wafer—these be- Projector of Color Transparency Film come a system’s microprocessor. Lamphouse Unfortunately, current chip fab- Red M Y M+Y= Red rication processes cannot place the required number of densely- White Green C Y C+Y= Green packed photosites on a chip to Blue C+M= Blue match the resolution of conven- Light C M tional film. Film has a densely- Neutral C+M+Y=N.D. packed structure of picture ele- density C M Y ments because these elements are not manufactured and are not Color dyes formed The resulting dyes approximate the scene directly limited to any physical in scene when viewed with white manufacturing capability. Rather, light from a projector film picture elements are created on an atomic level. Figure 9: Color formation in photographic film

Page 24 Photography for reproduction ly does in digital imaging. High- Early used the erator must develop skills to resolution film is less sensitive to additive red, green, and blue interpret and correct for miscal- light, and requires more expo- (RGB) photographic process culations and standard variations sure, because the light-sensitive similar to the RGB glowing in originals. Standardization is crystals are smaller and have less on a TV. Since RGB likely to improve when more surface area to collect light. More pigments could not be created on photographs are created digitally. light is also needed for digital a minute chemical level, they Digital photographs are more imaging so that all the photosites could not produce as much reso- consistent, so the quality control can be activated. When more lution and this approach was loop can be tightened between photosites are activated, more abandoned with the exception of the photographer and the print- picture elements are used to Polaroid instant photography. er. Until this happens, inconsis- make up the image, and greater tency will prevail as a conse- resolution is achieved. Current Relationship between quence of mixed imagery. severely restricts how photographer and printer Many photographers are small and numerous these photo- trained to produce display origi- sites can be when compared to Film-based photography is nals for gallery applications. high-resolution conventional capable of producing images Such originals usually utilize film. with a greater and most, if not all, of the range of In color photography, the higher resolution than digital tones the imaging system can same light-sensitive silver halide cameras. The main problem is produce. It is a common practice principles are used to form a that the detail and tonal range of in photography to make sample latent image, although the devel- film-based photographs are swatches of the highest and low- opment of the visible silver greater than the capabilities of est densities the photographic image from the latent image is printing presses. Digital images material can produce and use just a preliminary step. Color have less dynamic range than these as aim points for placement film contains silver salt layers film-based photographs, so they of the highlight and shadow. that act as catalysts in the forma- are closer to the range that the This procedure ensures a wide tion of cyan, magenta, and yellow press can reproduce. Many film- dynamic range, which is appeal- (CMY) dyes in the final image. based photographers use the full ing for display purposes, but is Bromide is released as a by-prod- range of tones available in film inappropriate for even the best uct when the silver is formed in and are not aware of the tonal printing conditions. Original these layers during development. limits of the printing process. In prints made for display purposes This bromide by-product reacts many cases, the printer is able to can have a range higher than with an oily substance, called a compress tones in originals at a 100:1, while transparencies can color coupler, in the film. There point where they are not easily range from 250:1–500:1 and are couplers in the layers of the detected, such as in dark shadow above. In one example, the range film that produce CMY images areas. from white paper to maximum upon contact with the bromide. Many factors of the printing ink density in one press impres- The silver formed in the produc- process can be standardized, al- sion can reach 20:1 and duotones tion of the CMY dyes in color though conventional photo- on coated paper can reach 100:1. processing is bleached out in the graphs are almost never the same It is unfortunate that many pho- later steps of development. and variations are hard to antici- tographers are not aware that Therefore, the final image con- pate. Because photographs are tone reduction can reach up to tains only CMY dyes (Figure 9). often inconsistent, a scanner op- 50%. Some photographers have

Visual Communications Journal 1999 Page 25 the impression that a printed fac- Measured photography use to conform the scene bright- simile is possible and informa- Prepress scanning and image ness range of their subjects to tion such as “match original” may processing technology have average press conditions (Sinar, be the only input given by the made correcting original images 1987). Measured photography photographer. Faced with this far more flexible and rapid, but can convert the density range of type of unrealistic instruction for have not solved the basic prob- ink on paper to an f-stop range a long range original, it is easy to lems of tonal incompatibility that can be used by the photog- see why printers may be skeptical between photographs and print- rapher in setting up lighting in of the value of communication: ing processes. Standards, such as the studio or fill-in out- “Photographers are becoming measured photography, have doors. The f-stop range is set by careless and submit photographs been proposed to assist photog- measuring the ratio between the with inferior quality that cause raphers in conforming to repro- key and fill light with a light many problems in reproduction,” duction parameters. Measured meter. The key light is the or “it is realized that photogra- photography attempts to match brightest and defines the direc- phers will construe any effort to the range of tones in original tion of the shadow in the scene. get them to reduce the lighting photographs to those that can be The fill light is dimmer and contrast of their originals as an reproduced under local offset determines how much detail will attempt to stifle their creativity” press conditions. Many digital be present in the shadow. (Bruno, 1989 p. 94). photographers go a step further For excessive scene contrast in The importance of graphic and are now in more direct con- outdoor situations, use of an aux- arts training for photographers trol of reproduction because they iliary light source will increase depends upon the environment submit images directly in the detail in the shadow areas. in which the photographer CMYK . Traditional Auxiliary light sources can works. A freelance commercial photographers depend more include a , photographer serves a variety of heavily on the skill of others in clients who may use different the production team. For pho- 1. Daylight Scene printing houses that produce at tographers who work directly F-stop Scale on varying levels of quality. Even in with art directors, knowledge of 2 2.8 4 5.6 8 11 16 situations where consistent cor- tonal losses provides the ability Shadow Highlight Meter Meter porate publication departments to communicate which tones are Reading Reading 6 Stops or art directors are involved, it most important to fit into the Scene Brightness Range would be desirable for the pho- press window. 2. Film Processing tographer to understand that The implication of emphasiz- Transparency Contrast Range: consistency can greatly reduce ing the controls available to pho- Increase Incurred in Film Processing for is 1.7 work and aggravation for the tographers is that quality control 6(1.7) = 10.2 printer. Experienced commercial efforts can be focused on solving 3. Convert to density photographers develop compe- common problems in originals 10.2(.3) = 3.06 tencies that enable them to inter- before they reach prepress. 4. Compare with Press Window pret which tones in a photograph Eliminating or fixing a problem 3.06 is too High in Contrast are reproducible. Once the as early as possible in the repro- Because the Average Press Window is: 1.8 - 2.1 graphic arts is understood as a duction chain costs much less process of compromise, photog- than corrections made further raphers can influence the repro- down the reproduction chain. Figure 10: Example of how a day- duction of images by choosing Measured photography is a light scene would not fit through a tonal ranges that are reasonable. method that photographers can particular press window.

Page 26 Photography for reproduction cards, and/or diffusion of the Multiply the unmodified Ekta- sunlight. Direct sunlight is con- chrome transparency contrast venient, but the ratio between range by .3 to obtain density light and dark is too great to be units. The result is 3.06, which is used without lighting modifiers. extreme contrast. In one example Photographers often measure of local conditions, a particular ratios between light and dark or press, ink, and paper combina- scene contrast on a light meter in tion can produce a density range f-stops such as f 2, 2.8, 4, 5.6, 8, from approximately 1.8–2.10 (4 11, 16, and 22. Printers measure f-stops) and 1.2 (3 f-stops) for Figure 12: A simple hand held light ratios between light and dark in uncoated paper (Figure 10). If meter can be used to measure the photographs in density units. photographers limit contrast to lighting ratio between highlight The scene brightness range of a this range, there will be less dif- and shadow. typical daylight scene is com- ference between the original and monly six f-stops, such as f-2 for the reproduction and a better the lighting ratio (Figure 11). the shadows and f-16 for the chance for success. In this exam- Measuring the ratio between highlights. When a color trans- ple, the photographer could be the highlight and the shadow parency is processed, it gains supplied with a range of f-stops created by the key and fill lights additional contrast. In the case of in which to conform lighting is a common procedure already Ektachrome film, the methods. In the photographic in use by photographers to set up contrast increase is by a factor of studio, lighting is under total lighting equipment. Although 1.7, making the transparency control, so the intensity of the fill specialized equipment, such as contrast range a total of 10.2. light can be increased to lower the fibre optic meter made by Sinar, provides greater accuracy, Specular Lights Diffuse Lights the same procedures can be fol- lowed with an inexpensive hand- held light meter that almost any professional photographer al- ready owns (Figure 12). Im- Spotlight Scoop plementing the procedure can be as simple as metering the high- light and shadow and conform- Top View Subject ing this range to local press con- ditions. Quartz lamp Umbrella reflector One major limitation of meas- ured photography is that results Spot light- Scoop light- often lack the visual contrast of Key Fill longer-range images. Altering Camera local contrast (such as the inclu- Sharp and harsh shadows Diffuse and feathered shadows sion of small reflections which do not contain detail), in conjunc- Figure 11: The key light defines the direction, shape and quality of the shad- tion with keeping total contrast ow. The fill light is dimmer, often more diffuse than the key and fills in the within the press window, often shadow cast by the key. The fill light intensity can be adjusted by moving the offers a good compromise. light back forth or adjustment of a light attenuator such as barn doors. An ideal image would contain

Visual Communications Journal 1999 Page 27 only that range of tones that can rections and special effects possi- arrived yet, in a complete sense, be reproduced by the printing ble with digital imaging, it is only because of the cost and resolu- process without compression. possible to realistically reproduce tion factors explored earlier in Based on this ideal, the greater detail that was captured at the this paper. In the mean time, the responsibility for tonal reproduc- time of exposure. This is just as printer and the photographer do tion should reside with the origi- important with digital imaging not have to wait for increased nator of the image. In its present as it is with conventional photog- communication and standardiza- form, will raphy. If detail in the shadow is tion to happen as a natural con- not ever be able to precisely important and the photograph sequence of the switch from film match reproduction require- contains no detail in the shadow, to digital. In the interim, local ments for this ideal. The expo- as is typical in a sunlit scene, no refinement of suggested stan- sure and development of a multi- amount of digital processing can dards, such as measured photog- layer film does not offer the bring out detail that does not raphy, can increase standardiza- degree of precision and quality exist. However, detail can be arti- tion. control that digital cameras have ficially added from another the potential to achieve. For this source. It may also be possible to References reason, tone control cannot rest electronically enhance detail solely in the hands of a photogra- from a deep shadow in an image, Bruno, M.H. (1989). Status of pher who uses conventional film. which may be useful as evidence printing: A state of the art report. The scanner operator should be or scientific documentation, but Salem, NH: GAMY. perform fine adjustment correc- such an image would exhibit Molla, R. (1983). Concepts, tions that are not practical on the extremely poor image quality in a principles, and skills required for film exposure and development commercial publishing context. the optimum operation of a color level. scanner. (Unpublished doctoral The ideal of providing an Conclusion dissertation, University of West image that precisely matches Virginia, 1983). reproduction capabilities is Technology has a great ability Molla, R. (1988). Electronic drawing closer with the advent of to blend tasks and job categories. color separation. Montgomery, low-cost and high-resolution di- This has especially been the case WV: R.K. Printing and Pub- gital cameras. When high-reso- in the printing and publishing lishing. lution digital cameras achieve industries over the past few years. Sanders, N. (1983). Photo- wider adoption, measured pho- Photography can be seen as the graphing for publication. New tography standards could take on persistent missing link in the York: R.R. Bowker. increased importance. An indus- reproduction quality control loop Sinar, Quadgraphics and try-standard tonal range, or local because of an often artificial sep- Black Box Corporation, (1987). press conditions, could be pro- aration between the photogra- Measuring photography for offset grammed into the digital cam- pher and the printer. This artifi- reproduction. Switzerland: Sinar. era’s microprocessor. When the cial separation will be blurred as lighting ratio, as detected by the digital imaging becomes more About the author CCD image in the camera, wide spread and when most all exceeds the programmed range, a images originate as digital data. Dr. Chris Lantz is the Asso- warning or code could be The potential for a new level of ciate Professor of Instructional provided in the viewfinder. standardization and consistency Technology and Telecommun- It is important to realize that in prepress is important. How- ications at Western Illinios even with the wide range of cor- ever the standardization, has not University

Page 28 Photography for reproduction