View Full Version : Film Testing For B&W: Why and How from Very Basic to Fully Explained

4-Sep-2010, 22:57
Hi everyone. I use this forum constantly and the people on it have helped me learn a great many things when I find myself stuck. Well, I hope this will be another one of those situations. I am immersing myself in as much photographic knowledge and information as I can and I am currently enrolled in photography courses as well so please make no mistake, I am not looking for someone to provide a full 4 year seminar in one post. I am simply looking for some clear clarification that I know a great many of this forum's participants may be able to offer.

I have been searching for and reading everything I can find on film testing and why it's important, the many methods available, etc., but I have been unable to find a source that offers a basic explanation in layman's terms offering a fundamental and basic explanation of why and how and then a progression into the more advanced and mathematical specifics of the practice. Most of what I have read seems to start in the middle assuming the reader has a solid understanding of the basics of film testing which I do not believe I have. I'm looking for a linear explanation from the most basic explanation progressing to the more advanced that I can understand and put into practice relative to where I am in my understanding of the photographic process and my specific purposes.

As a starting point, my range of knowledge has typically been more specific to equipment and the mechanical nature of cameras (I started as a collector and am now moving into practicing photography with the tools that I have collected). I am most interested in doing B&W contact prints on 8x10 and to a lesser degree on 5x7. I do not own a densitometer but I am more than willing to purchase one if that is indeed the most efficient and accurate method of testing my film and equipment/ process combinations. From what I understand, I would be looking for a transmission densitometer (please correct me if I am wrong). I have a Pentax Spotmeter V which I have come to understand is a very useful tool in film testing and I have also read that there is a method for turing this spot meter into a densitometer. For my purposes I will not be enlarging prints so I believe adding an enlarger to the equation would be an unnecessary step (again, please correct me if I am wrong). Lastly, I am now beginning to explore doing my own development so my understanding of that process is still limited.

Can someone please offer a very basic explanation of why testing film would be important for me if I am shooting B&W and contact printing as opposed to someone who is shooting 35mm or medium format and enlarging. Is there a difference in the importance of this between these? Why?

What is/are the best, most effective, and most consistent (I understand this is objective) method/methods of testing film? This (http://www.kenleegallery.com/html/tech/testing.html) method? Using a transmission densitometer? Using the Pentax spot meter as a densitometer? I'm not necessarily looking for the easiest way or the least expensive way, I fundamentally want to understand this and use the best method for me both personally and legitimately.

How exactly is it done? What are the possible tools used? Is there an exact and tested workflow that yields the best (most dependable and consistent) results? In any explanation please explain as fully as you can assuming I know basically nothing. I think this will be immeasurably useful for not only myself but everyone else who reads this in the future.

Lastly, and this depends on the answers to the above questions, what would be the ideal (meaning realistic and at least relatively affordable) equipment i.e. spot meter rig, densitometer, step wedge, etc., to use?

I apologize if anyone feels that this has been discussed at length enough times and I will gladly accept and links that you can offer that you believe will direct me to the answers and information I am looking for. Also, I fully understand that I am probably turing this into more of a mountain than it needs to be. I tend to do that but it is simply out of a strong desire to understand fully. For those who understand the daunting nature of developing a fundamental and solid understanding of film testing, I understand that I am asking for an explanation of a very daunting subject matter and I appreciate any help that is offered. Looking forward to reading your responses!

Doremus Scudder
5-Sep-2010, 03:14
OK Francesco, you asked for it :-)

Chapter 1: Basic Explanation of Why You Need to Test Your Film

Film is manufactured to exacting standards regarding sensitivity (speed). This is directly related to the way the film is developed (i.e., dependent on developer time and activity). It is therefore speed-tested with a standard exposure and with a standard developing regime dictated by the ISO and monitored and executed using very precise, expensive measuring devices and procedures.

Unfortunately, the light meters and shutters we commonly use are not nearly so accurate. Nor do we use (or even find useful) the specific development schemes dictated by the ISO. These and a host of other irregularities creates a rather significant range of possible error in both film speed and contrast for any given user. Personal testing using your shutters, light meter, developing technique and printing materials is necessary in order to make sure you are exposing and developing your film correctly for your equipment, development and, finally, your chosen printing materials.

If you don't test, you run the risk of incorrectly exposing your film and developing it to a contrast range that you will not be able to make satisfying prints from. Granted, this risk is different for different sets of equipment and developing styles, and you might get lucky with the printed starting points for exposure and development given by the manufacturers. You might even never need anything else. However, the chances of this, in my experience, are slim. There is usually an adjustment to both exposure and development needed in order to optimize quality.

If you underexpose your film, you lose shadow detail; things you wanted to show up in the negative are simply not rendered since they didn't get enough exposure. Overexposing, also a possibility, is not as bad, since black-and-white film can usually perform very will with overexposure. However it does increase grain and makes you use slower shutter speeds or wider apertures than you could have (an important factor for many). These exposure errors are corrected by determining you personal E.I., which means that you set your meter to the film's effective speed with your meter and techniques. Normally, discriminating photographers end up using slower speeds than published (more exposure).

Developing to a contrast range that is not compatible with your printing materials can result in prints that are flat and muddy looking, with no real blacks and whites (too little contrast) or prints that are too contrasty, with whites and blacks with little detail and no range of mid-tones in between (too contrasty). Even if the contrast you develop to can be compensated for by extremes of paper grades (i.e., using the softest or hardest filtration), better prints will usually result from negatives tailored for a mid-grade (paper grades 2 or 3). Furthermore, the error inherent in metering and different lighting means that, no matter how carefully we work, even after testing, many negatives will have more or less contrast than optimum. That's what the extreme paper grades should be reserved for. Without any testing or calibration, it is very easy to get a negative that is simply unprintable due to too much or too little contrast. This is what we are trying to avoid by testing.

Sure, you can bracket exposure and tweak development by "feel," and generally try to arrive at a system that works without testing, but this takes time, film (read money) and results in missed shots along the way. A little time spent testing reaps real rewards in the future.

Without a knowledge of photographic materials and how they react to changes in the system, and without conscious control of the methods and techniques, a photographer may as well take his film to the corner drugstore to be processed and see if they "come out." With such a knowledge, a photographer can not only get his photos to "come out," he can, to a large extent, plan and control the final result. This is the primary reason for testing.

Finally, once you have a basic E.I. and a "Normal" developing scheme (i.e., one that works for the majority of medium-contrast situations) and are working confidently with that, you will find that making adjustments to get better results for extremely contrasty and extremely flat situations follows logically. If you shoot sheet film, you will easily fall into tailoring exposure and development for each negative depending on the contrast of the situation and the desired result. If you shoot roll film, you will easily know which exposure compensations to make to arrive at the optimum negative for your development scheme.

Chapter Two: Basic Explanation of Testing Prodedures

Testing film is normally a two-step process. First, in order to find the effective film speed for any given film you use in conjunction with your meter and developing regime (personal E.I. or Exposure Index), you need to determine which exposure produces the minimum usable density on the negative for a given developer/time/agitation scheme. Once you have determined that, you then test for the correct development time for your developer/agitation scheme to produce the right contrast range for your printing materials. To summarize, testing involves first a film-speed test to determine personal E.I. and a development-calibration test to determine the developing time for optimum negative contrast.

The determining "standard" for these tests is your printing paper (and to a lesser extent, print developer). The paper you choose to print on interjects yet another set of variables into the entire equation. Although paper grades appear standardized, corresponding paper grades are rarely the same from manufacturer to manufacturer. Therefore, you should, ideally, calibrate your technique to the printing paper you intend to use most often. In practice, however, we often use different papers to refine our system; perhaps a particular negative prints better or has a better "feel" on one paper than another.

A caveat: the science of sensitometry deals with characteristics of photographic materials and quantifies things to a very exacting degree. As a general rule, practicing photographers do not need such precision. When testing, don't get caught up in trying to achieve a high degree of scientific accuracy. Keep in mind that we are only trying to achieve a negative that prints well. If a higher or lower contrast grade of paper, or a different paper altogether, is needed occasionally when printing, that is close enough; your system is working well. If you consistently need very contrasty or very soft paper when you are shooting for a mid-grade, then you need to refine your calibration. When testing, err on the side of overexposure for film speed tests and do your best to tailor your "Normal" contrast for the middle of the contrast range of the printing paper you use. This will give you latitude in the printing step for errors in visualizing, metering, exposing, equipment functioning, etc., etc.

Please see the next post for chapters 3 and 4 (too long for one post)

Doremus Scudder

Doremus Scudder
5-Sep-2010, 03:15
Chapter Three: Some Testing Methods

First, you need to realize that the majority of testing methods are just different ways of arriving at the same goal (a printable negative). They range from less to more scientific depending on the need of the photographer and the type of photography being done. Large format allows individual processing of negatives and is a comparatively slow process usually employing very careful metering techniques. This, coupled with the expense of larger film lends itself to more accurate testing methods which reduce the waste of time and materials to a minimum. 35-mm street photography, for example, often relies on less-accurate metering and a more hit-and-miss approach to capturing the image. Moreover, one cannot easily develop frames from roll-film individually. These considerations lend themselves to a looser, less-precise testing and calibration regime. Some different calibration "systems" follow.

The Zone System was developed by Ansel Adams. Its aim was to simplify and apply the science of sensitometry to the actual practice of photography. It was designed primarily as a tool for visualizing the results (or range of possible results) one could get from a scene of given contrast and the variables inherent in photographic materials and procedures. It divides the tonal scale into 9 (or 10) zones from black to white, and the photographer "places" shadow values on the scale and then chooses a development scheme to control the highlight values. A Zone I value on the negative is used to determine film speed. This is identified either by use of a densitometer or by a visual method. This latter involves printing an unexposed area of the negative at the minimum time needed to achieve maximum paper black and then noting which density achieves the first marked separation from maximum black when printed at the same time (my preferred method, by the way, but inherently more subjective. See Minor White et al. The New Zone System Manual). Since it relies heavily on careful metering of the scene, determining contrast range, deciding on how the final print should look before exposure and, subsequently, different developing schemes for individual negatives to achieve the desired effect, it lends itself best to large-format photography and sheet film. However, there are many variations and modifications to the technique for different metering methods, roll-film use, etc. etc. The resources for this system are exhaustive and easily accessed on the web and in the photographic literature.

BTZS, or "Beyond the Zone System," developed by Phil Davis is an expansion of the classic Zone System. It is more scientific, relying on the use of step-wedges (pre-calibrated stripes of different density on a transparent base) and graph-plotting software to even more precisely match negative contrast to the printing paper. It is more accurate than the Zone System, but requires more careful metering, a greater range of developing options and times, and the use of a hand-held computer in the field to assist in determining exposure and development. The learning-curve, testing time and exposure methodology of this method is more extensive than the Zone System. It can result in a significantly higher degree of accuracy, thereby saving materials and time. As you may guess, such exactitude finds its home in large- and ultra-large format photography, where material expenses and the effort to set-up and compose a shot often only practically allow one exposure to be made.

At the opposite end of the spectrum are a number of what I term "No-Name Systems." These are usually simplified versions of the Zone System or generally follow the "expose for the shadows and develop for the highlights" adage. Most of these rely on a visual evaluation of contact sheets or prints. A "proper proof" is made (clear areas of negative prints "maximum black") and shadow detail and overall negative contrast is evaluated. Based on the proof sheet, exposure and development are adjusted to achieve desired shadow detail and contrast for "average" situations. As you can see, this less-quantified approach applies better to photography that uses averaging metering methods, a quick-moving-get-the-shot approach and roll film. Usually, one standard developing time is used and variations in subject contrast are dealt with by changing paper grades. Each photographer tries to find a personal E.I. and developing scheme that fits their subjects and working methods, and often differs greatly from one photographer to the next, even though film and equipment may be similar. It is the desired result and the average of overall subject matter contrast that ends up determining both film speed and development. A street photographer may desire a more gritty, underexposed/overdeveloped look than a portrait photographer who strives for smooth skin tones and fully detailed shadows and highlights. Knowing what to do with exposure and development to achieve different effects allows photographers to change styles and looks to match how they wish to render a subject.

Chapter Four: Conclusion

I hope that this quick-and-dirty overview (incomplete at that), answers most of your questions. I see that there is one I haven't addressed: that of the difference between enlarging and contact printing. In my estimation, there is no real difference in the kind of testing one would do for contact printing or enlarging. What you must determine for either (and generally, for any kind of black-and-white photography) is how accurate an exposure and development system you need. Considerations for this are what format you use, how you meter, what your subject matter is, how fast you work (landscape or action photographer), what type of person you are, etc., etc. To give a personal example. I usually shoot 4x5 and enlarge. My subject material ranges from landscape to architecture to still life and natural detail. I usually take 20 minutes to set up and expose a scene. For me, metering with a spot meter and using my own version of the Zone System gets me negatives that 99% of the time print within one grade of the paper grade I note in my exposure record. I use two or three different films and calibrated them visually using proper proofing and the printing papers I like. I have a dozen or more development schemes and develop each negative to the contrast range I determine at the time of exposure. That may seem complicated, but it pales in comparison to the BTZS described above. That system, for me, is more than I need. If I were shooting 11x14 film, however, I would seriously consider moving to it, as it reduces waste and missed shots. As it is, I can more easily shoot a back up when I'm not sure of the exposure in cases where I am unsure.

On the other end of the spectrum, on the occasions when I shoot roll film, either medium format or 35mm, I usually work faster and use the camera's built-in averaging meter. In this case, I abandon the classic Zone System and its individual development schemes and shoot for one standard development, adjusting exposure based on the estimated contrast of the scene (more exposure for more contrasty scenes, since the meter wants to drop the shadows, less exposure for flat scenes to reduce grain a bit). I then adjust paper grade to deal with the different contrast negatives on a single roll. Note, however, that I have arrived at my own personal E.I. and a "standard" developing time for this system as well by careful testing beforehand.

Now that you understand more about film testing, the possibilities and the advantages, you need to evaluate your needs and choose a starting point. This site and other on-line resources will give you all the details you need to know for the testing you need to do. At a minimum, I would recommend learning how to make a proper proof and evaluate your contact sheets for shadow detail and contrast. You can then adjust exposure and development to refine these parameters. If you shoot roll film, you may need no more. If you shoot large format and meter with a spot meter, advancing to the Zone System (or Beyond) is a logical step. And, there are numerous stops along the way, or variations that you can use as needed for your particular requirements, once you have mastered the basics of film testing and calibration.

Best of luck on your photographic journey,

Doremus Scudder

Bruce Barlow
5-Sep-2010, 05:17
I hate to be a contrarian, but film testing is easy, simple, and mechanical. No fancy stuff is required.

All I'm trying to do is get the best information on the negative. That means exposing enough to get details in the shadows (by establishing the proper ISO for the film/developer combination I'm using, often less than the manufacturer claims), and developing long enough to get a good density in my whites, but not too much (by making identical negatives of a textured white surface and developing them for different amounts of time).

Once I've established those two things, I no longer need to think very much, which is good, because I want to be thinking about the photograph (the creative stuff). Metering and exposure can be done pretty much on automatic pilot, and the negatives look good every time. If I want more contrast, I can adjust development time by testing for normal-plus-one-stop, or whatever suits me.

It works for any format, and even 35mm benefits from it. Will negatives be "perfect"? Nope, but "close enough for photography." And certainly close enough to make a fine print.

It is - mostly - qualitative rather than quantitative. But I photograph things in the real world, which are qualitative. I don't photograph step wedges, not see a need to.

It's all laid out in my book. It's a morning's worth of tests, with some time thrown in to let negatives and proofs dry. Simple, reliable and repeatable.

As a final toss of a rock into the pool, Richard and I find that the people who come to our workshops who want deep. technical knowledge of exposure are trying to hide behind that to avoid confronting the hard part - finding the right place to point the camera, because they refuse to come to grips with the fact that they'll only get 5 keepers out of 100, and that feels like failure. Nah, it isn't. It's part of the experience.

5-Sep-2010, 07:16
You actually don't test the FILM, it is your system that you are testing. In the"Zone I Exposure test", you test your meter, shutter, etc so you can expose the film properly. The film, of course, has been manufactured to exacting standards.
In the development test, you see how the film responds to YOUR combination of developer, time, temp, agitation to get the correct contrast for YOUR printing technique.

Bruce Barlow
5-Sep-2010, 07:25
IC is spot-on. IC's The Man!

5-Sep-2010, 07:40
If you are going to spend the time learning to test your system my advice would be to do it right, i.e. buy a densitometer (not very expensive at all on ebay) and a copy of Phil Davis' Beyond the Zone System and study it carefully. BTZS takes a bit more time to learn than regular Zone but once you have it down it offers several advantages, 1) it is more precise, 2) testing new films is easier and faster, and 3) the testing procedures provide you with a lot more information about exposure and development.

Some people will argue that you don't need to test film at all to make good prints, and that may be true. However, considerable satisfaction is derived from understanding how to precisely control your materials, even if the control and precision is not always necessary.

BTW, great overview Doremus. But I would argue that metering in the field is not any more difficult than zone metering, in fact many BTZS users would claim that it is both easier and faster in most conditions.

Sandy King

Ken Lee
5-Sep-2010, 08:11
Just curious:

Aside from those who shoot Tri-X (at ~200, going back to Fred and/or Ansel), how many people actually shoot their film at a speed which is different than the manufacturer's recommendation ?

No Tri-X people please.

Not interested in your developer or development time either: Just your ISO please.

John Kasaian
5-Sep-2010, 08:30
First I'll shoot and soup film following the directions on the box. If I don't like the prints I get from the negs, then I'll test it.

'Cause I'm lazy, thats why.

5-Sep-2010, 08:36
Just curious:

Aside from those who shoot Tri-X (at ~200, going back to Fred and/or Ansel), how many people actually shoot their film at a speed which is different than the manufacturer's recommendation ?

No Tri-X people please.

Not interested in your developer or development time either. Just your ISO please.

Depending on the lens/camera combination -

100 Tmax - 80 ISO majority of the time

FP4+ 125 - 100 ISO all

Adox Pan 25 - 20 ISO mostly, two lenses like it rated at actual 25


David Hedley
5-Sep-2010, 09:26
Aside from those who shoot Tri-X (at ~200, going back to Fred and/or Ansel), how many people actually shoot their film at a speed which is different than the manufacturer's recommendation ?

Ilford Delta 100; EI50 - 80, depending on whether it's N-1 or N.

5-Sep-2010, 09:30
I am working through testing on Arista Edu Ultra 100 4x5. I used a densiometer to do my film testing and got an EI of 25. This just didn't sound right so I went through the test a second time and got the same result. Anyone else getting numbers that are about 1/4 of the ISO? No big deal if that's what I have to shoot to get rich blacks so be it. But I think a lot of folks just go with half the ISO as a matter of routine without testing. So they really are not getting everything out of the film. By the way thanks for all the great advice on this forum. I love having found a place to talk photography not just show off your work.

Brian Ellis
5-Sep-2010, 09:35
You test to determine film speed because the film manufacturer's stated speed may or may not be accurate for you, your equipment, your methods, and your goals for a particular negative. You didn't ask specifically about testing for development times but film speed and development times are inextricably intertwined so if you do one you would normally also do the other.

The goal in testing film speed (and development times) is to arrive at a system of exposing and processing film that will allow you to make the best possible negative. The "best possible negative" doesn't necessarily mean a negative with detail in the darkest important shadow areas and in the brightest important highlights though that's a very common goal for many negatives. But "the best possible negative" in the context of testing means the negative that will allow you to make the print you want to make as easily as possible given the fact that you would normally be exposing film under a variety of lighting conditions.

FWIW (very little) but to answer Ken's question, I exposed TMax 100 at an exposure index (EI) of 80. Other people I know use an EI of 50 for TMax 100. I rated Ilford HP5+ (a nominal 400 speed film) at an EI of 200.

The best single sources I know of for learning darkroom procedures including testing is Ansel Adams' book "The Negative" or Fred Picker's book "Zone VI Workshop." Actually if you buy and study all three books - "The Camera," "The Negative," and "The Print" - by Adams you'll know all you're likely to ever need to know and more for practical b&w photographic purposes. Adams' books are still in print I believe. Picker's is not but it comes up occasionally on ebay and other places. I'd consider Picker's book the "down and dirty" source for quick information that you can easily apply right off the bat and Adams' books for more in-depth knowledge over the long term.

Bill Burk
5-Sep-2010, 10:19
I shoot TMY-2 two different ways. I'll call it snapshots and landscapes.

Snapshots, I shoot at the box speed - 400. I develop these to ASA spec.

Landscapes, I shoot at 64 placing the darkest spot on Zone II. This oddly low rating was due to a gross error. I made a camera test and vignetted the low zones.

Some long discussions seem to validate my 64 speed because it guarantees I am on the straight-line.

Bruce Barlow
5-Sep-2010, 13:20
HP5 - 200. FP4 - 64. Tri-X, 320.

Paul Bujak
5-Sep-2010, 13:39
FP4 - 125
APX100 - 64
Kodak 4131 (20 years old) - 32

5-Sep-2010, 14:00
One good thing that came out of testing for me is that I realize how far from published speeds and development times my equipment and process is. Second, being new to large format I got lots of practice loading film and developing film. I ruined a number of sheets of film by making silly mistakes, but at least I learned this without ruining real shots. Third, testing helped me to figure out a system for doing things like keeping track of what was shot on this film holder, or which holder is empty vs exposed before going out to try this in the real world. Lastly, I found the process to be very long and I used a lot of film and chemicals, so I think that will make me stay with one film and one set of chemicals instead of jumping around trying this and that. I really don't want to do this again, and my agreement with myself is that before I shoot one single picture I must finish all the test for any new film or paper. If I allow myself to start snapping pictures chances are I may not ever get around to doing proper testing. So that's this newbies couple of ounces of new things learned. One other thing I was able to standardize things to what is room temp for me, I live in the desert southwest and I promise you room temp here is nowhere near the 68 degrees that most things assume. So that means I don't have to rely on time temp charts or fuss with heat or cooling chemicals. I have a system that works just for my darkroom.

Steve Sherman
5-Sep-2010, 20:44
Just curious:

Aside from those who shoot Tri-X (at ~200, going back to Fred and/or Ansel), how many people actually shoot their film at a speed which is different than the manufacturer's recommendation ?

No Tri-X people please.

Not interested in your developer or development time either: Just your ISO please.

Much would depend on lighting conditions typical starting point, FP4 @ 100, HP5 @ 400 -500

Darin Boville
5-Sep-2010, 22:27
Two brief thoughts here to add to the already excellent comments:

1) Just beneath the surface here but not detailed explicitly is the idea of variability in each step of your process, from film to print. There are many sources of variation. Some of the biggies are shutter speeds that differ from lens to lens, consistency of developing method (agitation, how careful you are about temperature).

Some problems, like shutter speeds that are different than the marked speeds or light meters that read a tad high or low are no problem at all as long as they are consistently off. Since they are consistent the error will be incorporated into and compensated for in the test.

By looking carefully at your process and doing "testing" you not only run your test but, more importantly, you become more aware of these sources of variation and learn how to minimize them. Just squeezing out the variation alone will, in and of itself, give you a clear sense of control over your exposures and contrast. The process will suddenly start to respond in predictable ways to changes that you make (longer or shorter development times, changes in exposure).

2) I've been surprised over the years how well a shortcut works: Instead of testing, ask someone to tell you what EI they use for their film, and how they process it. Then do *that.* Then do testing if you want to fine tune things.


6-Sep-2010, 00:21
Ilford PanF 50 ISO my adjustment is 40 EI. I add it because I saw that no one mentoned it. Running some "tests" for personal EI, Normal development, +- development along with using a densitomiter to get those readings is the key. Plot them and make your own H&D curves.



neil poulsen
6-Sep-2010, 00:48
. . . but I have been unable to find a source that offers a basic explanation in layman's terms offering a fundamental and basic explanation of why and how . . .

Let me take a stab at this. The premise on which proper exposure and development of film is based is the following principle.

EXPOSE for the shadows, and then DEVELOP for the highlights, put forward by William Mortensen in his book, Mortensen on the Negative published in 1947.

Testing film involves determining the minimum exposure that will show the least detectable density in the deepest shadow, namely Zone I. So clearly, this definition is about how to properly expose film for the shadows. TECHNICAL STUFF: Ansel Adams defined this least detectable density as 0.1 density units above film base plus fog. To calculate this speed, determine the ASA on the meter that yields this level of exposure after reducing the light by four stops. (i.e., the difference in stops between a Zone V and a Zone I.) Note that, this tested speed will typically be a lower ASA than that specified by the manufacturer.

After exposing for the shadows, why develop for the highlights? The reason follows. Proper film exposure and development is about matching the sheet of film to the contrast range in the actual scene. Operationally, this is accomplished by ensuring that both the shadows and the highlights will print correctly in the final print. (This involves using a spot meter, so that one can separately take readings from the shadows and from the highlights in a scene.)

It turns out that changing development times does not have much affect on how the shadows will print. It’s proper exposure that makes the shadows correct in the print. Development times have a much greater impact on how the highlights will print in the following way. As one increases development time, film contrast increases, and highlights print higher in the print. Correspondingly, as one decreases development time, film contrast decreases and highlights will print lower in the print. Thereby, scenes of greater contrast require less development time so that highlights won’t get blown out, and scenes of lesser contrast require increased development time so that highlights will look like highlights and not be muddy.

So exposing for the shadows and developing for the highlights amounts to the following. Properly expose the film to “lock” the shadows into place to make them correct in the print. (Remember that shadows are read separately from highlights using a spotmeter.) Then, select the best development time so that the highlights will print correctly in the print. In this way, one has matched the negative to the scene by having both shadows and highlights print correctly in the print.

As to the more advanced topics on how to test for film speed, how to test for different development times, and how to read a scene to determine the best exposure and the best development time, much has been written. (See previous posts as well.)

Let me add a word as to why manufacturer's stated nominal speeds are different from the above tested speeds. Manufacturers assume that the exposure will most often be based on an average exposure of the entire scene where a spot meter might not be available, and that the film will be processed by a lab at the manufacturer's recommended time and temperature. So, changing the development time based on highlights will not be possible.

6-Sep-2010, 01:37
Wow! Thanks so much everyone! You have all really helped me get a more solid idea of what I've been trying to understand and this thread really became exactly the valuable resource that I was hoping it would become! Thanks all!

Chuck P.
11-Sep-2010, 09:56
TMX in D76 1+1: EI 100 for all dev times from N-2 to N+2. When planning -2 dev a 1/3 stop increase in exposure is given, when planning +2 dev a 1/3 stop decrease in exposure is given; this is to account for increased fog at +2 dev and decreased fog at -2 dev.

TMX in HC-110:
EI 64 for "N" dev
EI 100 for "N-2" dev
EI 50 for "N-3" dev

Testing by the traditional ZS method.

Stephen Benskin
16-Sep-2010, 21:31
The primary reason to test is to test the film in your processing conditions and mostly for the contrast at that. I believe the tendency for people to focus more on the film speed than the film's contrast comes from necessity because the testing only uses two data points, you need to determine where Zone I falls before you are able to determine the contrast. Unless you plan on doing a lot of testing with multiple films and developers and are willing to do some serious studying, I'd recommend sending it to Fred Newman. While I don't hold with all the tenets of Beyond the Zone System, their testing will be more than sufficient to get you working. But if your want to do your own testing there are some things to consider.

The best testing results come from knowing your variables and limiting as many as possible. If you are testing the film and developer combination, test just them. There are enough variables connected to processing to keep anyone busy. Testing your entire camera system along with the film and developer incorporates too many variables. You'll never be able to identify the influence of any one element. If you want to test your camera system, test it separately. Bench test the lenses and shutter. The axiom that by testing your film with your camera system incorporates your equipment into the equation is a false one. Somehow it's gotten into the photographic lexicon but it's not realistic if you think about it. Simply from a practical stand point, in order to do a thorough film test with your system you would have to do a film test with every lens at every f/stop at every shutter speed with each body you own.

Even if you limit as many variables as possible, there are some that many people tend to overlook - latent image keeping, color temperature, and one of the biggest influences and least thought about, flare to name a few. As flare is difficult to control, it is best to eliminate it from the test but factor it in later. Testing with a camera and a gray card produces minimum flare which negates the precept that testing such as the Zone System incorporates flare into the test. How long you hold your film between exposing and processing will have an affect on latent image and consequently the resulting negative densities, and depending on the spectral sensitivity of the film and photocell of the exposure meter, the color temperature of the light and color of the subject can have an influence on the results.

Then there are the many common assumptions, memes, and myths:

- The reason why so many people using the Zone System method of testing have speeds different from the manufacturers is because the two methods are different. The difference between the meter reading and the film's speed point is 3 1/3 stops. ZS uses four. While the ISO model assumes the shadow exposure falls 4 1/3 stops below the metered exposure, it also assumes a flare factor of one stop.

- A density of 0.10 isn't he minimum usable density.

- Photographic speed and quality is defined by gradient and not points of density.

- Speed point isn't where the exposure is necessarily supposed to fall. It is only where the speed of the film is measured.

- The fixed density method of 0.10 as the speed point is only accurate in determining film speed for normal. It will produce inaccurate speed results for films developed above or below normal.

- The ISO speed equation .8/Hm incorporates a 1/3 stop safety factor into it.

- While Zone V equals 18% reflectance, the meter calibration point has an equivalent reflectance of 12% assuming a 7 1/3 stop range with a highlight reflectance of 100%.

- There are a number of ways to factor in flare. The most common are fixed and variable. While fixed is easier to use, variable is more realistic.

- There are also a number of methods to determining the degree of processing depending on the various conditions. Which ones best reflect what Normal, plus and minus processing should be?

If your assumptions are incorrect, your interpretation of the results will also be incorrect. The axiom garbage in, garbage out is very appropriate. You don't have to know everything in order to test, but you don't want have unquestionable confidence in dubious results either.

Fortunately, you don't have to go to testing extremes in order to photograph. There is an acceptable range of variation in any system. It's hard to really screw up a photograph. Disposable cameras have a fixed aperture and shutter speed and they produce satisfactory exposures in most cases. That's because shooting conditions fall within a bell curve. I believe over 80% of all exterior conditions fall within a two stop subject luminance range. Good exposures aren't hard either. B&W film speed used to be 1 stop slower before 1960 and there's little difference in quality between then and now. There's a lot of slop there. Most photographic "systems" work within most conditions. It's the extreme situations, the other 10 to 20% of conditions, that culls the herd.

I think you'll discover the biggest variable is the photographer himself. The way you like to shoot, your metering preferences, and the type of results you like will have a greater influence on how you shoot and process than any tested film speed. Go ahead and test the film, do some shooting, and then make adjustments to reflect your personal preferences.

Stephen Benskin
17-Sep-2010, 05:01
I believe the tendency for people to focus more on the film speed than the film's contrast comes from necessity because the testing only uses two data points, you need to determine where Zone I falls before you are able to determine the contrast.

The sentence should read "...comes from the specifics of Zone System testing which only uses two data points and everything is keyed off Zone I."

23-Sep-2010, 21:01
Arista Edu Ultra 100 - shot at EI 50
Ilford HP5+ - shot at EI 320

24-Sep-2010, 12:17
If I test a film in this way for my 5x4 camera will the result EI that is found apply to my 10x8 camera assuming the same film and processing? or should I test the 10 x 8 as well?

Thanks for your opinions.

nn :)

24-Sep-2010, 12:28
I spoke to my mentor about this. If you are using reducing backs on your 8x10 to shoot 4x5 then you should test on 8x10 (to account for flare and other such things). You can apply your results to 5x7 or 4x5 from the same camera if it is the exact same film i.e. TMAX 100 for 8x10, 5x7, and 4x5. You should not test 4x5 film using a reducing back and try to apply the results to a larger film on the same camera. Test the largest film and you should be fine with smaller films on the same camera.

If your 8x10 and 4x5 cameras are two separate cameras i.e. not using reducing backs on one camera, then you need to test each camera. Variables that are built into testing are the lens, bellows, film, etc. If a major factor like the bellows is different, you will get different results. The test is meant to give you personal information specific to your exact setup. Hope this helps.

24-Sep-2010, 12:28
I went through all this but the bottom line became that the sciency-stuff got in the way of me enjoying photography! Thankfully bw film has a lot of latitude.

Testing is impractical for people such as myself who use a combination of lense/cameras/enlargers. Hell I use 5 MF cameras and 3 handheld 4x5 plus 2 8x10s, and a variety of lenses. Trying to keep track of all that was near impossible.

Also, it relies on the assumption that film batches are in fact made "to exacting standards" without variation. I also strongly suspect that there are a host of other variations that are not taken into account, ie: ambient temp differences effects on shutter speed.

24-Sep-2010, 12:43
Cyrus is right, the sciency-stuff can get in the way. I have to keep reminding myself of that so that I don't let it!

If you're using a bunch of different cameras, I see the point that testing for all of them can be a bit much. I am a collector so I like to use the cameras in my collection but predominately I use one 8x10 Deardorff for 8x10 and 5x7 via a reducing back and I'll be getting a 4x5 reducing back soon as well. For me testing is very relevant in this situation but I would not test each different MF camera or Speed Graphic that i use because that would just be impractical. For my film, TMAX 100, if you look at all of the data across the proverbial board you'll see that the best results are very often seen when shooting TMAX 100 at iso 64 or iso 80 regardless what format you are shooting in. On MF I use these numbers (instead of testing) and get superior results compared to using the box iso almost all of the time.

Also, the films these days are pretty consistent. I wouldn't consider anything with as many variables as film to be considered "exacting" or "without variation" but if you know your film and the conditions you are shooting under then film tests coupled with the almost exacting manufacture of modern film will give you very consistent and relevant information to use in your photography and development. At least thats my take but everyone is different! Thats the beauty of photography!

Ken Lee
24-Sep-2010, 12:57
Apparently, very few people determine a personal film speed which varies dramatically from the multitudes. The difference rarely amounts to more than 1 f/stop, if that much.

While it's a valuable exercise, that acquaints us with the entire process, it seems to me that the real value comes in determining developing times, more than film speed.

Bruce Barlow
24-Sep-2010, 13:09
Apparently, very few people determine a personal film speed which varies dramatically from the multitudes. The difference rarely amounts to more than 1 f/stop, if that much.

While it's a valuable exercise, that acquaints us with the entire process, it seems to me that the real value comes in determining developing times, more than film speed.