I've been told that 35mm film is known to be over rated speed wise by the various film makers and therefore in order to get better contrast in your negatives you should always lower the film speed.For example shoot 100 asa at 80 asa and 400 asa at 320 asa.My question is: Do most photographers follow this rule?

-- Anonymous, April 29, 1997

Answers

When you find out please tell me, I'm interested. Also, tell me how you'd develop the film for example if it were a Ilford 400asa shot at 320asa. How long in the developper? Thanks!

-- Anonymous, April 29, 1997

When you find out please tell me, I'm interested. Also, tell me how you'd develop the film for example if it were a Ilford 400asa shot at 320asa. How long in the developper? Thanks!

-- Anonymous, April 29, 1997

The film speeds vary with the film, photographer, water in your area, chemistry to a degree & your perceptions. Some aren't quite what the manufacturer says in your particular situation both fast & slow. The only way to tell what your is doing is to test it & see. As to an 'always' case, it just doesn't happen. I shoot the same film, same emulsion batch, same processer, etc., at 2 different speeds depending on the camera body I am using due to the meter readings in each. But, the film is in actuality the same speed. As to getting better contrast? Test your films to get the contrast and look you are trying to achieve. Most photogs I know don't really follow any particular 'rule', but seem to rely on a mystical mumbo-jumbo of 'Ansel did it' or similar worship of someone. Few actually test their materials. Instead they follow what someone else did rather than trust their own instincts & what they think. Too much herd mentality out there. "If so & so did it it must be right". Not necessarily so. There is so much of this that whole cults of copycats who don't learn to think abound. They do what 'the current guru' says & few test, print & hold the prints up to the light of day. No names here & no slight intended, but they are followers & generally unsure of themselves & looking for approval. This photo stuff is & isn't science & art both. It is creative expression above all(my view only) and all or nearly all of us need to learn to express the creative side. That isn't done by following anyone specific, but by experimenting-going beyond reading & mimicry. Try it yourself. Read & take everyone(especially opinionated fools like this letter writer) with big grain of salt. So shoot your film at a particular ISO rating, then process it & try it at the 1/3 stop difference mentioned in your letter & try it again-you will be hard pressed to see a difference with such a small change. Your thermometer, film agitation method, etc., alone can make bigger changes than that for you. Just expose for the detail needed in the shadows & print accordingly. The results in the final print are all that really count. If it is there you did well. There may be easier ways to do it. After all, look at the results of Weston & Gene Smith-at times working against the medium but good results none the less. Work at it & you will get better. But get locked into a 'system' or a mindset, no matter what, & you kill the creativity. Most of the time there is no 'always' in your photography. Good Luck

-- Anonymous, April 29, 1997

establishing your film speed

As Dan Smith mentioned in his reply, this is somewhat subjective, but there are some methodical ways you can check it out for yourself. The really tedious meticulous way is using sensitometry and the Zone System...for that see Ansel Adams "The Negative" or other such books. Since most of us don't have access to a sensitometer, a much easier way to get a handle on it is as follows:

First set your camera ISO to the film rated value. Next, go shoot several subjects in different lighting, bracketing each shot significantly, at least +- 1 f-stop. (For this, don't choose subjects that are incredibly contrasty because you'll go off the scale in one direction or another no matter what f-stop you use.) A "gross" test is to shoot the each subject at a "normal" setting (whatever speed and f-stop your meter tells you), 1 stop open, and 1 stop closed. A finer test would be to open and close by 1/3 stop or 2/3 stop increments, going at least to +-1 full stop. Recall that changing the f-stop is equivalent to changing your camera's ISO setting. Develop the film "normally", whatever that is for you. Now take a look at the negs with a loupe on a light box. For each subject, you'll have a set of progressively denser negs. By examining these, you can see which of each set has sufficient shadow detail and (hopefully also) good contrast, so you can decide whether the film's stated ISO rating is best for you, or if you should change it for your camera/metering system. If the negs for one stop open are always better than the ones for the "normal" setting, for instance, for you the film would be rated 1 stop slower than the manufacturer's rating (e.g., ISO 400 would be 200 for you). There are subjectivities in this - some people like denser negs in general because they think they're easier to print, whereas others like them as thin as possible but still with detail in order to minimize graininess. You'll have to decide for yourself what works is most important for you.

If you can't decide what's dense enough but not too dense, you can go one step further...Take a set of the negs for a subject you think had relatively "normal" contrast and print the "normal", -1 stop and +1 stop negs in such a way that you think they look right, with "correct" contrast in the print. Negs that are thinner will tend to need higher grades of paper (or filter for VC) whereas negs that are denser will tend to need lower grades. Negs of "average contrast scenes" that print nicely in the grade 2-3 range are probably a good density. If you find yourself having to always print with grades 3-5, your negs are probably consistently thin (underexposed), whereas if you always need grades 0-1 or 2, your negs are probably consistently dense (overexposed). There are tons of caveats - how you develop affects these things, if you consistently take photos of low contrast or high contrast subjects etc. Nevertheless, these are trends that can help guide you in selecting a good ISO rating for you.

A class I took once did this process (just with the negs, not the printing), and 14 of 15 people ended up resetting their ISO from 1/3 to 2 full stops lower (320 to 100) than the manufacturer's rating of 400. Granted the teacher really liked dense negs, but it does tend to suggest downward ratings work for many people.

-- Anonymous, April 29, 1997

More on film speeds

Carson- Darkroom online (www.soundnet/~lanoue/index.html) has a step by step process listed for determining your film speed. A densitometer is required, but you can usually find a local processor or camera shop that will take the readings for you free or at a nominal charge.

The only thing I would like to add to the previous responses is that your film speed is also a calibration of your meter to your development process (which makes it very important). One of my meters is 2/3 of a stop "off" from what is considered normal. Fortunately it is off throughout the entire spectrum so it is not a big deal. I found that out doing film tests. I rate TMAX 100 at 125 where generally most people will come up with an ISO of 80. So, test first then let your creativity soar! -Doug

-- Anonymous, May 04, 1997