Why test for film speed?

[hitam_jantung]

Film speed testing is a subject loaded with passion, dogma, misconceptions and

misinterpretations of various "sytems", from the Zone System, and beyond, by

devotees and the uninitiated alike, and given the level of sophistication of

modern film engineering, manufacturing and quality control, it might

reasonably be asked why photographers bother to test film at all, when the

best testing by hobbyists consistently confirms manufacturer's data? What

follows is my opinion and reasoning on the value of film testing for the photo

hobbyist.

 

Why film speed is the least important characteristic one can test, and why it

is so doggedly pursued by so many photographers-

 

Film speed, or sensitivity is the least important of the commonly tested film

characteristics because it is printed on the box by the manufacturer, is

changed very little by variations in processing, and these variations are

generally within the latitude of the film.

 

Film speed is the subject of intense interest, scrutiny, debate and testing

because it is one of only two quantifiable controls, along with development,

the photographer can exercise in the practice of making a negative for

printing.

 

When photographers test for "personal" film speed, they're actually testing

for a desireable deviation from true film speed as indicated by the

manufacturer, which almost always means de-rating their film, rarely more than

a stop, which usually falls within the latitude of the film. Almost no one

ever concludes from their testing that they've been overexposing their film,

and decides to increase the rating, so these tests ostensibly determine how

much added exposure to give a film for the desired results, which can more

easily be determined by simple trial and error, incremental refinements.

 

Why testing for development time is wasted effort-

 

The best reason to test any film is to determine a development time that will

produce a negative density range that closely matches the exposure scale of

the printing paper for easy printing. Traditionally, graded papers were used,

having fixed exposure scales, so individual negative density range was

adjusted in film development to meet the paper's exposure scale. Today the

vast majority of photographers shoot roll film and either scan their negatives

for digital printing, or print on VC paper,and in either case, the printing

process can be adjusted to suit the negative density range far more easily

than the reverse. Simple, incremental adjustments to development time are all

that's needed to consistently produce negatives that print easily either

digitally or on VC papers.

 

Why film testing is a waste of time and effort for most people most of the

time-

 

It's not that I'm anti- film testing, it's just that in-camera zone system-

like testing regimes are as useful in sensitometry as a yardstick is to a

machinist, or like setting an atomic clock to a sundial. Some people seem to

believe that any testing is better than no testing, but that misses the point

that testing has been done, extensively, under controlled conditions, by

trained profesionals with state of the art equipment. For those who shoot

sheet film and have the ability to develop each exposure individually, and who

print on fixed contrast papers, a higher degree of precision is possible, and

sensitometry can provide much useful information in a short time, using a

minimum of materials, when understood and effectively applied, and given the

required facilities. Most photographers have neither the understanding or the

facilities to effectively practice sensitometry, and are probably at least as

well off using simple trial and error methods as trying to implement some

approximation thereof. So, for the vast majority of photographers who shoot

roll film and print either digitally or on VC papers, small incremental

adjustments to the manufacturer's recommendations by trial and error are the

most simple and direct route to easy printing negatives, and for those few who

require a higher degree of precision, in-camera testing methods are too

imprecise, and offer little improvement over simple trial and error

refinements of technique.

 

Why people test-

 

I think most people test because they sincerely believe it to be the best way

to improve their photography and better understand their materials; I know

that was true for me, and led me to study sensitometry which, in the end,

improved my photography and my understanding of my materials, but it was a

long way around, and informed my opinion that for most people, most of the

time, film testing is wasted effort. I know some people will not be disuaded

from testing regardless of the case made against it, but for others who just

want to photograph and feel testing is an unwelcome requirement, it might be

helpful to know someone who has invested coutless hours and thousands of

dollars in materials testing finds it to be a pointless detour for most

photographers.

 

 

 

 

 

 

[stwrtertbsratbs5]

"It's not that I'm anti- film testing, . . "

 

All of your other comments indicate that you are anti-testing. So don't test.

[stwrtertbsratbs5]

I can figure out what I want to do with a new film in one evening. I shoot a few test rolls (or sheets), develop at a couple of different times, and then I borrow a friend's densitomiter and create a density as a function of time curve. So I spend a couple of hours and spend about $20. And as an additional benefit, I get to grab a beer with a friend.

 

Why do I test? Because I want to capture shadow detail 2 stops below middle gray and produce negatives that print, as a starting point, on a 2.5 filter. Using the manufacture's ISO data and development times doesn't usually get me there. And I also want to understand how the film will behave if I need to use other EI's.

 

I'm not sure how you are testing, but perhaps you need to revise your procedures. It is possible to get so wrapped up in testing that you don't get out and take real photos.

[ronald_moravec1]

I run a small test on every bulk roll I buy to be sure all is well.

 

This includes shutters, meters, the actual batch of film, and everything that goes into the process.

 

I you prefer to wait until a dys work or your vacation pics are ruined, well I guess that is up to you.

[hitam_jantung]

I've never ruined a roll of film exposing a major manufacturer's film at its rated speed and processing with a recommended developer as recommended. The fates are with me, I suppose. Either that, or the manufacturers actually know their products. If you prefer to do a lot of testing to figure that out, it's up to you.

[fourthst]

Knowing your film speed and proper development times allows one to envision what their

photographs will look like before they take the photograph instead of relying on luck. Fairly

important in many aspects of photography. Street photography, maybe not as important.

Capa's invasion shots are a great example of content over technique but honestly, how often

does that happen? I don't toss to many shots for technical reasons. I just wish I didn't toss so

many because they stink.

[fourthst]

"I don't toss to many shots for technical reasons. " That should be "too" many.

 

I thought of an analogy while correcting my spelling. When you buy a car do you get the

mileage the car company claims? I never did. Sure it may be close but their testing method

and my driving style vary quite a bit. I wouldn't want calculate and drive across a desert

based on milage claims. I'd run a quick test first. If you are a professional and your work is

just close but not quite on, you may find yourself wishing you were stuck in a desert.

[peter_fitzsimons]

The testing takes very little time as has been mentioned and I saw a good improvement in my negs after doing the tests.

[Vlad Soare]

Hitam, I also have never ruined a roll of film by exposing it at the recommended speed. However, as I said on the other thread, there is one film that never gives me any shadow detail at box speed. Is the respective roll of film really ruined? No, not at all. At least with my subjects it's not. But it's darn annoying sometimes. <br>

One can use a speed-enhancing developer and get perfect results with the box speed. Or one can shoot subjects with no dark shadows. Or one can use an inaccurate lightmeter. There are many possible reasons why the box speed works for some people and not for others.

<br><br>

I wouldn't go as far as to say that I ruined films because of this, or that finding a personal EI is paramount. Sometimes, however, I want to make sure I'll get in the shadows exactly the kind of detail I want. Testing the film helps me achieve that.

[Vlad Soare]

Another example: Delta 3200. It's not a real 3200 film, it's more like 1000+ something. I have exposed it at 3200 and developed in various developers at the recommended time. I got very good results, but the shadows are always completely black, with no detail at all.<br>

Does the box speed work? Of course it does. Did I get good results? Yes, I did. Could I ever get detail in the shadows at 3200? Nope. I don't think so. :-)

[matt_needham]

"...when the best testing by hobbyists consistently confirms manufacturer's data?"

 

College was the last time I saw anyone else doing film speed tests. As I recall very few people ended up with personal film speeds that matched the manufacturer's recommendations. The common result was a film speed 1 to 1.33 stops slower than the box label. I feel my own personal film speed testing since college has helped me get consistent and predictable results.

 

That said, today the majority of the film using photographers that I know personally don't bother with with film testing, and they seem quite happy with their results. I guess they just wing it, and get a feel for what works for them.

[sg_adams]

just to make lazy people say it isn't necessary.

[rothelle]

It's always to test your equipment for the best results. Being stupid is one thing. I still have friends who been wasting film because they do want to take the time out to run a little simple test. I say if your happy with the result your getting then why post. Don't test. I never like to get into this battle any more. It's a waste of time same as not testing:-)

[rick_jones5]

Hitam - you are safe - Phil Davis has left the building.

[Monophoto]

Many years ago, I took a workshop on the Zone System. I'm glad that I did, because it caused me to become much more disciplined about the technical aspects of photography.

 

And to this day, I will always conduct a film speed test when adopting a new film.

 

But I'm far more interested in producing images than I am in photographing sheets of mat board taped to the side of a building, and the only time I change films is when the film I am currently using as "standard" becomes no longer available. So I make sure that I have careful notes on how to conduct that film speed test, cuz I don't do it often enough to trust myself to remember.

[stwrtertbsratbs5]

Hitam - shoot as you like. Some of prefer to have more contol of what we produce. But, hey, I drive a manual transmission, too.

[hitam_jantung]

Did no one read my post? I've tested innumerable films and papers over the years, and my lab is equipped very well for the purpose with calibrated sensitometers, densitometers, and automated processors. I know how to test, which is how I know that in-camera testing is next to useless, and unnecessary for most photographers, most of the time. I never suggested anyone slavishly adhere to the manufacturer's ISO rating, just that it's a better starting point from which to deviate incrementally through simple trial and error observations of actual results, than overly complicated and uselessly imprecise in-camera, zone system-like testing. As I wrote in my post, many people will use these tests regardless of their true merit, and discount out of hand anyone who suggests it isn't necessary, or even beneficial to do so. To continue Paul's analogy used above, how wise do you think it would be for the owner of a new sports car to crack open his car's "brain box" computer and "adjust" its tuning based on the sound of the engine? Given the training and experience and analytical equipment, a tuner might be able to fine tune his new sports car to more closely match his style of driving, but for most people, most of the time, it is far more likely that they would have a negative impact on their new car's state of tune than to improve it. However, if they notice their car is idling too slowly, they might be able to incrementally adjust the idle to improve the situation without getting hopelessly muddled. Vlad, my point is that you could adjust your exposure based on simple observation without resorting to some kludgy in-camera testing regime, and save a lot of time and frustration. Not enough shadow detail? Increase exposure. Simple. No testing necessary. Shadows not black enough? Decrease exposure. No testing necessary. By the way, if you want to shoot Delta 3200 for shadow detail, be prepared for very dense, flat, grainy, unsharp negatives. This film was designed to be pushed, and shooting it for shadow detail is working against its nature, despite its "True speed" but that's up to you.

 

My point in a nutshell is this: Given the latitude of modern films, and the accuracy of their ISO ratings, the flexibility of scanners/VC papers, and the level of precision possible with in-camera testing, this kind of film speed testing is not very productive. When I test a film these days, it is because the film, developer, or printing process is non-standard and the manufacturer doesn't provide the data I need. In these cases my exposures are made in a calibrated sensitometer, my film processed in an automated processor, and the resulting negatives measured with a calibrated densitometer, providing a level of precision and data that warrants the effort. There was a time when I tested every film/developer/paper combination I used, and what I found was that for shooting roll films from major manufacturers and scanning or printing on VC papers, extensive testing was not necessary, as it only confirmed the manufacturer's data, and the flexibility built into the system coupled with small, incremental adjustments was all that was needed to secure reliable, repeatable results. Your experience might run counter to mine, but to suggest I'm stupid or that I don't test because I'm lazy, or don't know how to test reflects very poorly on yourselves, and your fundamental reading skills.

[stwrtertbsratbs5]

Hitam - you sound like a real wind bag. We don't care if you test or not. Why do you care that other people find it useful?

[dave_wilson1]

We test a film to see how that film behaves with our equipment, personal developing and printing process in our particular application. The film speed is on the box and is set by the manufacturer under very stringent laboratory conditions which may not necessarily coincide with our own use of that film, especially with regard to the actual working latitude available to us. This is only one reason why we believe the film to be of a different speed, when really if tested against other films under the same stringent procedures they would be practically identical in their reproduction of Zone V. That one film is more forgiving or more tolerant of severe contrast should not lead us to believe that it's box speed is any different, just it's ability to tolerate what we do with it, so that's why I test. It's still 125 PlusX but I may index it at 80 to fit my personal habits.

[david_dorcich1]

Given the latitude of modern films, and the accuracy of their ISO ratings, last time i check no film manufacturer has come to my darkroom to make sure their testing for ISO matches my process.

 

That is why i test.

[lex_jenkins]

ISO standards are derived from testing within a very narrow protocol. It's only logical that using a developer other than the ISO standard developer would result in difference in *true* film speed - not personal EI.

 

If I'm recalling correctly, when with Ilford, David Carper said an Ilford engineer tested HP5+ in Microphen and got a true speed of 500. That's significant. Personally I didn't care for the look of HP5+ in Microphen and preferred it at EI 200 in ID-11. Now *that's* a personal EI. I didn't test, I just liked the look.

[sg_adams]

Testing is loaded with passion eh? Well I hope so for most as it is a wonderful feeling to enjoy what one is doing. And Dogma? Sure, yeah whatever, nothing wrong with a little structure. Missconceptions and missinterpretations of various systems? Could you explain some of these and describe how they relate to some of these systems systems you failed to cite?

You are stating as fact that testing by hobbyists consistently confrims manufacturer's data. Can you please support this with statistical evidence we can reference? In other words, proof?

Then you go on to say that what follows, your argument, is your opinion and reasoning. Based on your own personal expereince I take it? If one is going to make statements like the ones you are making here and elsewhere, you might want to start using some more substantial information than your own opinion and reasoning because that will only be held as groundless unless you can support it with some actual data besides what you read on a box of film, because there is an awful lot of literary and photographical evidence that suggests something a little different.

For example, you are claiming that film speed is changed very little by variations in processing, and that these variations are generally within the latitude of the film. Absolutley not to the first, and only sometimes to the second. You seem not to take the into account any notion as to the broad differences or lack of light that can be present in a compostion. There are too many variables, and it really depends on the film in question, and which developing chemicals are used, time, temp and on and on.

Then rather than suggest testing, you promote the use of "trial and error" to find "incremental refinements".

Check this out... the word 'trial' has a number of definitions, but I'll list a couple for you in case you don't have a dictionary handy. 1.the act or process of trying, testing etc. 2. a hardship, suffering etc. 3. a source of annoyance 5. an attempt, effort. Error: 1. the state of believing what is untrue. 2. a wrong belief. 3. something incorrectly done, mistake.

Did you catch the part about trying, testing etc...?

But in the second part of your suggestion, "error", and so choosing to use this word, your statement promotes not only testing, but at the same time supports "the state of believing what is untrue".(Websters, 1987) Don't look at me; you wrote it.

Your attmept to ground your premise with some other interesting comments like not needing development time testing is unfounded. Not necessary according to your reasoning. Not since traditionally graded papers aren't used anymore more by most people. Most folks now scan thier negs or print on VC paper alleviating the necessity of proper development since we are no longer concerned with negative densities and printing exposure values. Or so you say. You state that this is because the printing process can be more easily adjusted than the reverse, but failed to support anything regarding scanning film. My experience, and many of those I have spoken to,and numerous posts read here and elsewhere suggest that there is actually a need for properly exposed negs if intending to scan. As far as I know crappy negs make crappy scans, and only slight exposure and contrast adjusments work before the image structure goes haywire. But I am scanner challenged so I will leave that to the experts. And you make no reference to contrast, high, low, or middle values, with regards easily printing negs. Did I miss something? There's that thing called the curve, and some manufactures even make developer film speed charts available.

And what's all this about in-camera testing is to sensitometry what a yardstick is to a machinist. Where does one expose the film then? And just so you know, at the machine shop where I spend many of my daylight hours, there are a number of yardsticks. Pretty handy items. I was using one last week. They have extra marks on them. You don't have to use them to measure the yard.

Here again you also state that in-camera methods are too impresice and offer little improvement over simple trial and error refinements of technique. Right. We went over that already. But let me add that it might be a good idea to offer what device youare using or your methods for exposing film for your "trial and error" system if you are not exposing your film in a camera.

In closing you suggest that it will be helpful for some people to know that someone has invested countless hours and thousands of dollars in materials testing and thus finds it to be a pointless detour for most photographers.

I assume the someone that spent countless hours and thousasnds of dollars is the same person who wrote this contradictory reasoning. All it really says is that testing is a waste of time and unecessary,but at the same time, often in the same sentence, supports testing by trial and error. But based on what system? I myself take it that the system of trial and error suggested here is grounded in using box speed and manufacturer's recommended development times, while casting any idea of exposing for proper print and scanning negative densities, or at least workable ones, aside, because according to the writer, this is no longer an issue for most photographers because any adjustments can be made at the print or scan level. However, the premise, that testing is a wasted detour of time, effort and money, is, as was duly noted at the beginning, grounded on one person's opionion and reasoning, and lacks any real proof that what has been suggested is statistically founded. The only real reference given is the film speed we can all read on a small green, white, or yellow box.

Why test for film speed? I don't know, maybe to make better images on film and thereby in print. Makes more sense than the OP.

[sg_adams]

Vlad, I had some OK results using Delta 3200 fora grainy look that I later manipulated in the darkroom.

But there is shadow detail, and easily scanned and printed.

I can find my notes if interested.

[sg_adams]

Vlad, I had some OK results using Delta 3200 fora grainy look that I later manipulated in the darkroom.

But there is shadow detail, and easily scanned and printed.

I can find my notes if interested.

[hitam_jantung]

Robert,

 

I don't care whether or not you test, or how you do it; I'm just sharing my perspective on the issue based on my experience. You're under no onbligation to agree, disagree or comment, and your contribution to the discussion is enough to tell me what I need to know about you, and the value of your opinions.

 

 

Dave,

 

thank you for your considered response to the pertinent issues. Your reasoning is sound, but I would argue that you could accomplish your goals by simple trial and error incremental refinements based on evaluation of prints. This method takes into account all of the personal variables noted, but relies on qualitative evaluation of real images instead of trying to quantify values based on an imprecise methodology. I realize this distinction is lost on some posters to this thread, but trying to reason with them is as casting pearls before swine, and I won't bother.

 

David,

 

again, I'm not suggesting you don't deviate from the manuf's rating, I'm simply suggesting the deviation is likely to be slight, and easily managed by incremental adjustments based on the evaluation of real prints instead of relying on an elaborate and imprecise testing methodology to quantify these adjustments. My comments and observations are not directed at those who test, or want to test, but rather those who feel compelled to test because they believe there is no other way to refine their process.

 

Lex,

 

you make some good points re the differences between ISO, true film speed and EI. I would argue that the difference between exposing at 400 and 500 is not significant and well within the latitude of the film, but note that you were able to arrive at an EI that works for you by qualitative analysis and did not need to resort to abstract testing methods. Thank you for making that point in an uncomplicated way.

 

For those having trouble distinguishing between the trial and error methodology and the testing methodology, allow me to summarize:

 

Trial and error refinement is accomplished by incremental adjustments to exposure and development based on qualitative evaluation of real images made under actual working conditions during exposure, processing and printing, so all personal variables are accounted for. This method requires no special equipment or materials, and there is no procedure to learn. All that is required is a basic understanding of the reciprocals of exposure and development, and a need for improvement.

 

Zone-system type testing attempts to quantify exposure and development values as densities based on in-camera exposures of various test targets, using various metering techniques and improvised measuring devices resulting in the worst kind of abstraction with neither the value of real images made under typical working conditions, or the precision of controlled lab conditions. These testing methodologies require the user to learn needlessly complicated procedures, and sacrifice time and materials to testing in the hope that they will produce a precise exposure value and development time that will produce optimum results from their equipment and materials.

 

Most photographers shoot roll film (and if you don't believe me, the sales statistics for roll films vs sheet films are published and available for review; it's not even close, by the way), and most photographers print on VC papers (again, see sales statistics), so unless these photographers are shooting entire rolls of film of identical subjects under identical exposure conditions, there is no single optimum development for every frame. The best these photographers can do is to develop normally and make all of the exposures on a roll within reasonable limits of that development and the exposure scale range of their printing paper, but since they're using VC paper, that range is very wide. A high degree of precision in determining a development time is unnecessary for these photographers, and impossible to apply to rollfilm as typically used.

 

Film speed determination is a very, very simple adjustment,typically made in a single direction; towards more exposure, and almost always within one stop of the ISO rating, and more often than not, within 1/2 stop. Since shadow detail is largely a matter of taste, it makes more sense to evaluate actual prints than to try to define an abstract density value. If prints consistently show too little shadow detail for one's taste, it's a very simple matter to increase exposure incrementally until a satisfactory level of shadow detail is obtained, and since any values obtained by formal testing should be verified by field tests under normal working conditions, the formal tests themselves are wasted effort and materials.

 

I hope this clarifies my position, but if anyone is still tempted to respond with meaningless personal judgements, please think twice about how it makes you look, because I promise you won't impress me or intimidate me in any way. If you want to test, that's reason enough to do so, as far as I'm concerned, and you don't need to justify it to me, or contribute to this discussion. If you'd like to discuss the relative value of testing vs trial and error evaluation, I look forward to your contributions.