View Full Version : What is the fastest (& most economical) way of iso calibrating the film?

2-Oct-2010, 09:30

Lenny Eiger
2-Oct-2010, 09:55
Take some pictures, use a gray card for the metering, bracket the exposure and see which neg is the best one for you....


2-Oct-2010, 11:30
Look on the box.

If you want to find your own exposure index, then it will be a little more involved.

Jay DeFehr
2-Oct-2010, 11:54
Testing for film speed alone is not very productive, in my opinion. The film speed as determined by ISO testing procedures is more accurate than anything you're likely to do, and most developers produce speeds very close to ISO- few being as much as a stop slower. A little careful metering and bracketing, as described above, will be enough to determine how far off of ISO speed your developer is.

Sirius Glass
2-Oct-2010, 12:04
I agree with posts #2, #3, and #4. I shoot box speed. I have never had a problem with the box speed. I keep my cameras [shutters and apertures] and light meters in good operating condition. And, repeating myself, I have never had a problem with box speed. Maybe, though I do not have enough experience, since I have only been using cameras and film for just over five decades.

If I had six decades of experience, then there could arise a need to calibrate film speed on the proviso that I would then get a complete body replacement with an eighteen year old's hard body and become independently weathy. Otherwise, forget about it.


2-Oct-2010, 12:37
Film does not need calibrated. The film's ISO speed is printed on the box it came in.

2-Oct-2010, 12:44
Mainly due to curiosity, I’ve calibrated most of my equipment. At least once.

For example, my Pentax digital spot meter “over-exposes about 1/3 a stop” – according to two local store technicians. My Sekonic L-308s, they say, “under-exposes by 1/3 stop.” Their diagnostics are, of course, just one piece to the “puzzle of my satisfaction” w/ final film and print results…

I’ll spare you what I know about my cameras, lenses, enlarger, and preferred films, papers, film developers, dilution ratios, aesthetic goals, etc. Oh, the combinations, the permutations!

In the end – to keep my personal answer very simple – I usually shoot b/w film at one-half box speed (or a little faster), and shoot color slide film at box speed. Keep in mind, “it all depends!”

If I had never done tests, and had shot box speed every time, I’d still be happy. :)

(I just wouldn’t have had as much fun.)

Bibliography: Simmons’ Using the View Camera has a clever section titled “Establishing a Personal Exposure Index” – it’s in the “Zone System” chapter. See also John Shaw’s Closeups in Nature and its two excellent sections, “Metering” and “Running a Test.”

Daniel Stone
2-Oct-2010, 12:48
proof is in the print folks... NOT in how the negative looks, its in how the PRINT looks.

if you're enlarging, contact printing, other process, etc... its about getting enough shadow& highlight detail to satisfy your tastes comfortably.

I've found that shooting a few negatives of a normal contrast scene, maybe including a gray card if possible, then developing one for the recommended time/temp with your chosen developer+dilution, then PRINT the negative.

if you need more contrast, lengthen your development time, if you need more/less shadow detail, then adjust your film speed(on your meter) to compensate for how much you want.

simple stuff, no math or densitometry-whiz bang stuff... proof is in the PRINT.

that's IF the print/scan is the final product for you. Even if you're doing the hybrid thing(which generally needs less contrasty negs to keep highlights(that might be printable via silver/alternative process), but with digital means, too contrasty/blocked up to be really useable). Simply adjust your exposure and development to give YOU the results YOU want in YOUR prints.

now go out and make photographs!


Sirius Glass
2-Oct-2010, 13:02
proof is in the print folks... NOT in how the negative looks, its in how the PRINT looks.

Knowing how to use a light meter helps. Like aiming the light meter down so that you are not measuring the sky. Open the lens up if the scene is almost all white and you are interested in the dark object. Close the lens down if the scene is almost black and you are interested in the light object. ...


2-Oct-2010, 14:47
View Camera store and BTZS.

or if you have a densitometer and the software, you can do it yourself.

Calibrate your paper first then fit your tested film to the paper. so simple and once done really never needs to be done again -- unless you want to.

Armin Seeholzer
2-Oct-2010, 14:53
Use XTOL as soup and be happy to use your B&W films at film speed almost all and forever;--)))

Cheers Armin

2-Oct-2010, 15:10
I usually over-expose by 2 stops and develop slow in cold highly diluted rodinal. I get nice negatives easy to scan and print on grade 2 paper.

As I understand, developing is like a horse race where the highlights are the fastest. So in cold development I try to keep all horses at the same speed. Midtones would develop fully and stop, while highlights will be tamed and arrested before their full potential.

If you believe me, you over-expose at least 3 negatives, then you try find your time at a set cold temperature and given dilution. Then you scan/print and see which combination will make a print that meets your expectations.

Of course this is not applicable to all lighting situation (disclaimer).

Sirius Glass
2-Oct-2010, 15:27
Use XTOL as soup and be happy to use your B&W films at film speed almost all and forever;--)))

Cheers Armin

We have never talked, but I can tell that you are an extremely intelligent person because you are doing exactly the same thing I am. ;)


2-Oct-2010, 18:57
Take the rated ISO of the film. Cut it in half. Shoot and develop. Use a diluted developer and longer development times with gentile agitation. If your negatives come out gray you are on the right track.

A good step by step guide can be found at http://www.jerryo.com/teaching.htm

3-Oct-2010, 03:07
The problem is that whenever I use a diluted developer even 3:1 developer to water, the negatives come out with white speckles. I can't figure out why. If I develop in unconconc developer they are not there!

Ken Lee
3-Oct-2010, 03:59
Tri-X film aside*, most people shoot film within 1 f/stop of the manufacturer's recommended speed, after all is said and done. What really deserves testing, is your developing time.

This makes sense, because a given brand of film is unvarying for all of us. What varies, is our water, thermometer, exposure meter, agitation technique, etc.

You might find this brief article (http://www.kenleegallery.com/html/tech/testing.html) helpful.

* In many developers, Tri-X has a long "toe" section and an upswept curve. For at least 40 years, many people who test it, have given it an extra stop (shooting it at 200) to push the low values onto the straighter section of the curve.