By terri at Sun, 2007-01-14 11:04 Black and White Film Photography: A Beginner's Primer. Part VI: A basic exposure/development/printing system. by Jim Hannah Introduction. To put it simply, the technical goal [not to be confused with the artistic goal] in B&W photography is to have a good idea of what a final print will look like when you're ready to press the shutter release on your camera. To do this, the various steps in the exposure-to-print process have to be predictable - within reasonable limits. There is vast, and still expanding, literature available on this subject. Much of it is devoted to fine-tuning the some part of the process to a high degree of precision. Some of the techniques involved require calibrating camera/film exposure through densitometer readings of test negatives, and tailoring negative development to individual exposures. While these procedures are certainly valid and will produce results of the very highest quality, they also require lots of effort - and often considerable expense, as well. The beginning B&W amateur isn't necessarily prepared to make such an investment in time and money. The photographer starting B&W photography usually uses a 35mm or 120 roll film camera, rather than one of the larger sheet film rigs. A roll of film may well include exposures of several subjects, often with differing ranges of brightness from frame to frame. The highly precise methods noted above aren't really designed for this situation. This doesn't mean the beginner can't exercise control over his work. What is really needed is a simpler [and less expensive] system. The goal should be to produce an excellent, rather than the very finest, final print. The twin keys to achieving this are knowledge and consistency. The information given below describes methods which will provide satisfactory results. It's tailored to the roll film user and doesn't require a "one subject/one roll" approach. As for equipment, all that's required is a hand-held reflectance-type exposure meter, and an 18% gray card [see Appendix A]. Discussion. Let's begin by separating the B&W photographic process into its component steps. These are three in number: 1) film exposure 2) film development and 3) enlargement exposure and development. If you follow a systematic approach to each step, you'll end up with prints that will please you. Note: Enlargement exposure and development are linked together because the print development process is already rigidly standardized. Development of a print goes to full completion. Film development does not. The one place in the process where you can really control what happens, outside of print development, is the film development step. You have complete control over all of the factors which can affect the process. By establishing a strict, unchanging procedure, you can provide a rock-solid stable "anchor". Then you can adjust the other steps, if necessary, until they fall in line. The control needed in the film development step is easy to describe, so let's start with it. Film development. The one and only part of the whole B&W process that you can always control with absolute precision is film development. The governing factors are four in number: 1) developer concentration, 2) developer temperature, 3) development time and 4) agitation. There's no better starting point for establishing control than adopting the manufacturer's recommendations for your particular film and developer combination. These are intended to produce a negative which makes good use of the film's ability to capture a wide range of grays. These recommendations should form the basis of your standard procedure. Begin by standardizing your development procedure so that it comes as close as possible to the recommended time, temperature and agitation. If the developer has to be dissolved or diluted before use, dissolve it or dilute it in exactly the same way each and every time. If measurements are required, make them as accurately as possible with the equipment you have available. This doesn't mean measuring to the nearest 0.01 ounce! It does mean measuring accurately to the same mark on your measuring container each time. When ready to process film, check the developer with an accurate thermometer and adjust its temperature before pouring it into the developing tank. Place the tank in a water bath [water in a large bowl works well] brought to the same recommended temperature. Use an accurate timer. A clock with a sweep second hand or a kitchen timer which measures in seconds will do. Agitate the tank in the same way each time, and at precise intervals. In short, do everything you can to ensure that each and every roll of film is processed in exactly the same way. This covers three of the four factors of film development. The remaining one, developer concentration, can cause all sorts of mischief unless you deal with it firmly. When a developer is used to process a roll of film, some of the developing chemicals are used up. The developer becomes weaker. The next roll to be processed will be a bit lighter than the one before. This may not be noticeable in the first few rolls, but it happens regardless. Developer exhaustion with re-use is a slow, relentless process. There are several ways of compensating for exhaustion. One is to add a replenishing solution to the developer to bring the chemical concentrations back up to strength. Another is to lengthen the time of development as additional rolls are processed. Both of these procedures are less than exact and also require accurate record-keeping. They can be used, but there are a couple of simpler ways to control concentration. It's strongly suggested that you pick one of them and use it. The first is to use a "single-use" developer. These developers are formulated so that you dilute a quantity of concentrate to make a working solution for each tank-full. The working solution processes one tank of film and is then discarded. Each batch of developer, if accurately measured and diluted, is exactly the same strength. The second method is used with developers which aren't packaged as single-use concentrates. They can still be made to function in the same way. First, make up a standard batch of the developer. Then package it off into tightly-capped containers, each of which holds the amount required for your developing tank. Select containers which will hold the required amount of developer (or a little more) and which will have a minimum amount of air space when filled. By keeping the air space to a minimum [don't eliminate it entirely], the amount of oxygen which reacts with the developer is small. Use each portion for a single tank of film and then discard it. When using single-use developers, there is one last thing to consider and that is stability. Developers, either concentrated or diluted, lose strength with time. Check the manufacturer's recommended storage times for your developer and discard out-of-date stock. Note: Don't purchase and make up more developer than you will use within the storage period. Any money you save through purchasing in quantity will be lost when the developer goes out of date. With film development tightly controlled by adopting a single-use development procedure, let's move on to the next step. Film exposure. The best negative is one which has captured everything from the brightest highlights to the deepest shadows in a given scene. You can always manipulate the printmaking process to reduce the range of grays, but there's no way to recover lost highlight or shadow details if they aren't on the negative. The "correct" exposure for a given scene is usually that which comes closest to producing this ideal. In scenes where the range of brightness exceeds the film's ability to capture all of it, there is still a way to get a good negative, though there will be some loss at one end or the other of the range. One of the best concepts ever developed for understanding B&W film exposure is the "Zone" system. Note: Forget everything you've ever heard about the Zone System being complicated or difficult to understand. The trick to understanding any new idea is to nibble away at it in nice, bite-sized pieces. We don't consume an entire meal in one gulp, and shouldn't expect to learn a new concept in one instant flash. In what follows, do take the time to read carefully. If necessary, go back over a paragraph if it doesn't seem entirely clear on first reading. To assist you, whenever we nail down an idea, it will also appear in bold type. Imagine a strip of film about 9 inches long. Hold it horizontally. Now imagine that it's clear at one end and slowly, evenly becomes darker and darker gray until it's fully black at the other end. Next, let's imagine that we make a perfect exposure [ideal camera, ideal exposure meter, ideal development, etc.] of a standard 18% gray card* on the same type of film. When we process the film, we can match it to a shade of gray somewhere in the film strip. When we do this, it will end up matching the strip right smack in the middle! That's what makes an 18% gray card so useful. It's the same gray as the middle gray in an ideal negative. An 18% gray card should produce middle gray on a properly exposed film. Now let's make another exposure of the gray card, but this time we'll use the next higher f stop number on our camera [we'll leave the shutter speed at the original setting.] This will cut the amount of light reaching the film in half. If the original exposure was at f 8, we'll expose at f 11. The resulting negative will be a lighter gray when compared to the original. If we match it to our gray scale, it will be closer to the clear end of the film strip. If we take yet another exposure and again use the next higher f stop, the negative will be still lighter because we've again halved the amount of light and it will match a gray even closer to the clear end of the strip. Most general B&W films, processed in a general-purpose developer, will allow you to do this two more times and still have a negative that falls within the gray scale on the film strip. At that point, though, the gray of the negative will be near the clear end of the scale. If you again increase the f stop number, the result will be clear film. Let's go the other way. If we go back to the original "perfect" exposure and then decrease the f stop by one number, the resulting negative will match the scale at a point on the darker side of the center of the strip. If we go to the next higher f stop, the negative will be darker yet. And again, with general purpose B&W films, we can do this two more times. After that, if we again increase the f stop, all we'll get is a fully black negative. Note: This is a somewhat idealized situation. The real world isn't quite so cut and dried. But it's close enough to reality to meet our needs very nicely. Now, let's add this all up. A general purpose B&W film can handle a range of f stop numbers. There's the "ideal" exposure number, four f stop numbers higher than the ideal exposure number and four f stops lower than the ideal exposure number. This range is called the film's exposure latitude. General purpose B&W films have a latitude of 9 f stops. Chances are that you've realized that we could have just as easily kept the f stop number constant and changed the shutter speed instead to increase or decrease the exposures. In that case, the results would have been exactly the same. The film could have handled a total of 9 shutter speeds. There's just one more step to go now. Let's go back and look at our gray scale again. If we make a dot on it, showing where each of the different exposure negatives matched it, we'll have nine evenly-spaced dots on the strip. Now let's draw straight lines across the width of the film strip from top to bottom, placed midway between each of the dots. We have now divided the gray scale into 9 zones. Finally, we can number the zones, with Zone 1 located at the clear end of the film strip and Zone 9 at the black end. General purpose B&W film has a latitude of 9 zones. The center of Zone 5 is the same gray as an 18% gray card. What we've gained by thinking of grays as zones is a great mental "tool" which we can use when we go about taking a picture in the real world. Let's put it to work. When we look at an actual scene in the real world, the darkest shades we see are those of the deepest shadows. The brightest [highlights] are the lightest shades.** In a scene where the range of shades, from the deepest shadows to the brightest highlights, does not exceed 9 zones [or 9 f stops, or 9 shutter speeds -- it's all the same thing!] you can set your camera exposure for Zone 5 - 18% gray. Your film will capture the full range of shades as grays. The negative will have all the information in the scene. On an overcast day, when there's less contrast, the full range of shades in a scene may be less than 9 zones. Let's say that the range is only 7 zones. The same procedure applies here just as well. The safe exposure is Zone 5. Now you've even got a safety zone at each end of the scale. Before going further, let's take a break and talk about exposure meters. We used the meter in an imaginary situation above to read an 18% gray card. It determined the exposure to use to have that gray record as middle gray on the film. That's exactly what an exposure meter does. Any time you point the meter at a single shade of gray, whether it be the very lightest or the very darkest, the meter will tell you what exposure to use so that the film will record it as middle gray. That idea is important enough to spend a little more time on it. There's no way that an exposure meter can know whether you're pointing it at a shadow [dark shade] or a highlight [light shade]. A highlight in one scene can be darker than a shadow in another scene. The best the meter can do is tell you what exposure to use so that the shade you're pointing it at will end up in the safest part of the film's range: the exact middle - Zone 5. It does its best to make sure that you don't under- or over-expose that particular shade. It doesn't, and can't, tell you how to expose so that the shade will look the same on the film as it looks to your eyes. An exposure meter provides the exposure required to produce middle gray. That same ability of the exposure meter explains why it can usually give the correct exposure for an entire scene: it averages all the shades in the scene "lights and darks" and tells you how to set your camera so that the average ends up in the middle of the gray scale on the film. If the scene contains a good mix of grays, and the shade range doesn't exceed 9 zones, the exposure will capture all of the shades in the scene as grays on the film. You can actually use your exposure meter in three ways to determine the correct exposure for a real-world scene. Which method you choose depends on the scene. The first is to point your exposure meter at the entire scene. In most instances, there are a whole range of different shades in the scene and they'll average out somewhere around the middle of Zone 5. Set your camera for that exposure [shutter speed/f stop combination] and expose the film. A second way is to pick the exposure which would be half-way between that for the shadows and that for the highlights. By using a hand-held reflectance exposure meter, you can determine the exposure for the deepest shadows and the brightest highlights. Pick the exposure which falls mid-way between them. Rather than hoping the exposure meter will correctly average the scene, you're done the job yourself. Set the camera and shoot. The third method is to dig out your trusty old gray card, hold it so that the light falling on the scene is also falling on the card, and read the card with your meter. This, you now know, will give you a Zone 5 exposure for that scene automatically. Let's repeat these three methods: 1. Read the overall scene with the exposure meter. 2. Read the darkest shades and the lightest shades and average the exposure. 3. Place an 18% gray card in the same light as the scene and read the gray card. Each of the three methods [meter average, average of darkest/lightest shades or gray card reading] will usually result in a correctly-exposed negative for an average scene. However - and this is one very big however! - there are two situations in which only one or two of the methods will work correctly. Knowing about and recognizing these situations, and knowing how to handle them, is what good exposure technique is all about. The first type of scene is one in which the range of shades exceeds 9 zones [bright sunlight on snow with deep shadows under fir trees]. Your film will not be able to capture all of the detail in the scene. The only exposure procedure which will work here is to measure the exposure for the shadows and also measure the exposure for the highlights with your meter. That tells you the range of the scene. Then it's up to you to decide on the exposure to use to keep either the shadow detail or the highlight detail. Asking the meter to average the scene, or using the 18% gray card exposure, will put the exposure in the center of the range, resulting in losing detail in both the highlights and the shadows. You'll have to make a choice on which zones you choose to lose. You can move your exposure from the mid-way point between the extremes toward the highlight shades [faster shutter or smaller aperture] and have a better chance of capturing the detail in the snow. The deepest shadows will go completely black - no detail. Alternately, you can move the exposure toward the shadow shades [slow the shutter down or open up the aperture] and have a better chance of capturing detail in the shadows. The snow will go blank white with no detail. This is a good time to review what we've learned. 1) General purpose B&W film has a latitude of 9 zones. 2) An exposure meter provides the exposure to produce middle gray [Zone 5.] 3) Shadows should be in Zone 1. 4) Highlights should be in Zone 9. Knowing that, here's how to go about deciding on the correct exposure. If you want to retain the shadow detail, use the shadow reading and then go four f stop numbers larger to determine the actual exposure [e.g., go from f 4 to f.16.] Remember that in our imaginary exposures with the "perfect" film strip, we could go four stops before the film became clear. The meter, remember, tried to set the exposure so that the shadows would become a Zone 5 gray. By going four f stop numbers higher, you've put the shadow shades back down into Zone 1 where they belong. You could also have gone four shutter speeds faster. Same result. The highlights will be overexposed. If, on the other hand, you want to keep the highlight detail, use the highlight reading and then go four f stop numbers smaller [e.g., from f 16 to f 4.] The meter tried to set the exposure so that the highlights would become a Zone 5 gray on the film. Going four f stop numbers lower [or four shutter speeds slower] puts the highlight shades back in Zone 9 on the film. The shadows will be underexposed. If you're not sure whether you wish to keep the shadow detail or the highlight detail, you can avoid the decision for the time being by taking a shot at each exposure. You can even take additional exposures at settings between them. This is called "bracketing" an exposure. You can use a contact print to help you decide which exposure you prefer. Bracketing is like going to the dog track and betting on the rabbit to show! When a scene's shade range exceeds 9 zones, use shadow and highlight readings. Do not use a gray card or entire scene reading. The other situation in which a specific exposure method will not work is a scene in which most of the area is composed of dark shades, or in which most of the area is composed of light shades. If you meter the entire scene, the meter will give you its average. However, this average will not be half-way between the darkest and the lightest shades. If most of the area is dark, the meter will try to put the average into good old Zone 5. It will move the gray for the dark shades too close to Zone 5. The light shades will be overexposed and will lose detail. If most of the area is light, the opposite will happen. The meter will try to put the light shades too close to Zone 5 and the dark shades will be underexposed and lose detail. Whenever you realize that a scene contains mostly light shades or mostly dark shades, you can fall back on taking a shadow reading and a highlight reading and averaging them or you can unpack your 18% gray card, put it into the same light as that which falls on the scene, and take a meter reading of it. Either method will result in a correctly-exposed negative, as long as the range of shades doesn't exceed 9 zones. When a scene is mostly dark or mostly light, use an average of the shadow and highlight readings or read the 18% gray card. Do not use a meter reading of the whole scene. That covers film exposure. The procedures discussed will, if followed, ensure that each frame captures the shades you desired from the original scene. [See Appendix B] Enlargement exposure and development. Controlling the enlarging process differs from film exposure and film development in one very significant way. Once an exposure has been made, and once a film has been developed, there's little you can do with the negative to change it. What you see is what you have to work with. An enlargement, on the other hand, can quickly be re-made and changed until you're satisfied with it. The enlargement exposure is the point in the entire process where you can experiment to your heart's content. There are still a few parts of the procedure which should be followed. We'll get the development part out of the way quickly. In the article on contact printing, we noted that the correct development time for a print, using Dektol developer, was 2 minutes. This assured that the print was fully developed. If you went ahead and developed an identically-exposed print for 3 minutes, you would see no difference at all. By developing a print fully, rather than by trying to control the image characteristics by shortening the time, you nail the lid firmly shut on another possible source of mischief in the B&W process. That leaves the exposure to be considered. The exposure you use for a print has two components. One is the length of the exposure time. The other is the contrast of the print, selected either through the paper [single contrast grade] or through the enlarger filter [variable contrast paper.] The selection of the exposure time can be decided by use of a test strip. In general, try to pick the exposure time which will result in the brightest highlight shades being almost the white of the print margin and the darkest shadow shades being close to the deepest black that the paper can produce. This exposure time will make the fullest use of the range, or latitude, of the paper.*** The selection of the final print contrast is often made by examining a print of normal, or #2 contrast. If the subject matter needs more "punch" or "spark", increasing the contrast will often help. In the same manner, reducing the contrast grade will ˜soften" the feeling of a print if it seems too harsh. At first, the process will be trial and error, but with experience you'll be able to judge the process quite accurately. By understanding the various steps in this basic "system" of B&W photography and putting them to use, you'll have a dependable means of converting what you see in your camera's viewfinder into a print you'll be able to hang on your wall. * Thinking of 18% gray as the middle is no stranger than thinking of middle C on a keyboard. The center of the scale is D, not C. In school, C is considered as a middle grade, but C is only the third letter in our 26 letter alphabet. ** As a guide, deep shadows are about Zone 1 or 2. Plant and tree foliage will fall into Zones 3 and 4. Light rocks and the palm of your hand will be in Zones 5 or 6. Shaded snow is about Zone 8. Sunlit snow is Zone 1. *** General enlarging papers have a latitude of about 6 zones rather than the 9 zones of films. Most of this is due to the fact that negatives are viewed with the light shining through them, while prints are viewed with the light reflected from them. The next article will cover B&W filters. Appendix A. Exposure meter and gray card. A hand-held reflectance-type exposure meter is one of the most important accessories the B&W photographer can own. Please note the word "reflectance". There's another type of meter called an "incidence" meter. Incidence meters cannot be used for this system, though in certain applications, particularly studio portrait work, they can be of great value. If necessary a reflectance meter, coupled with a gray card, can provide the same information as an incidence meter. Why use a separate meter when many cameras already have built-in meters? First, because you'll often be using the meter to take readings of different parts of a scene. A separate meter allows you to set up your camera on a tripod and still take "spot" readings wherever you wish. Next, a hand-held meter provides you with the full range of shutter speed/f stop combinations at a glance. This can be very helpful when determining an exposure average or adjusting an exposure up or down by several stops. Last, hand-held meters often have a useable light level range far beyond that of the built-in meter. In dim lighting, this can be a significant advantage. An 18% gray card provides a reference which can be used for checking your exposure meter. It can also provide an "average" reading for a scene. Gray cards are inexpensive and can be purchased at any large photo store. If possible, get a package with two smaller cards in it. Store one card away from light. It can serve as a check on any fading of your "working" card. Appendix B. When the exposures have been correctly determined and the film development standardized, it's possible that the final results are not yet right on the nose. There are a few reasons for this. It's possible that the camera shutter speeds are not correct. The most common example of this is an older camera where the slow shutter speeds are actually sluggish. Camera shutter speeds can only be checked and re-set by a repair shop which has the appropriate equipment. Shutter speeds are usually consistent, however, even if they are "off" by a little. You can generally ignore small deviations. If your camera's shutter speeds are not consistent, they will be unpredictable and the repair shop is the only solution. Light meter calibration is a different situation. Assuming that the batteries are not old, your meter should give consistent results, even if they aren't precisely "on the nose". You can check your meter with a simple gray card. Wait for a bright, sunny day. Place the gray card in full sunlight and set your meter for ISO 100. Now take a reading of the card, being careful not to read surface "shine" or to shadow the card with the meter. The reading at ISO 100 should produce a recommended exposure of 1/100 second at f16. The difference between this and your meter's actual reading is the meter error. It's not necessary to have the meter adjusted unless the difference is extreme or the readings are not consistent. The meter error can be compensated for by adjusting the ISO rating until the meter reads the gray card correctly. Deviations of one-half stop or less can safely be ignored. If your meter is off by more than a half stop, you can use that information and your meter's dials to work backward and determine how to rate your film for that particular meter. It's tempting to adjust the film development process to compensate, but don't do it. Instead, change the ISO rating at which you expose the film. It's as simple as that. If you're using an ISO 100 film and the meter readings produce negatives are too light, expose the film at a lower ISO rating. If, on the other hand, the negatives are too dark, expose the film as if it were a higher ISO film. The ISO film rating system is also in zones, if you wish to think of it that way. Go from an ISO 50 to an ISO 100 film, and you can capture one more zone toward the dark end at the same exposure. ISO numbers double for each increase in zone 50, 100, 200, 400, 800, etc. From ISO 50 to ISO 400 is a shift of 3 'zones.'