film tests how to?

[quigon]

Hello. I'm going to run tests fp4+, hp5+ and delta 100 for the correct sensibility, n+1 and n-1 developments (procedure as described in A.Adams books). I usually use 4x5 and 8x10 formats for my photos, but I would like to use 35 mm films for the tests, because it's cheaper. I would use the same developer I use for developing large format sheets.
My question is: will the test be reliable also for large format or the fact that I change camera, lens and format would make the tests useless? :confused:
Luigi

[willwilson]

Ballpark only, really not accurate enough for precise zone system work. Although I have done a fair bit of testing and I still find myself going with my gut, as far as exposure/development, quite often. YMMV.

[John Bowen]

Luigi,

which is more expensive.....burning through 14 sheets of 4x5 film (6 sheets for film speed, 4 sheets for n- and 4 more for n+) or burning through a few rolls of 35mm then finding out that 35mm is NOT = to sheet film?

I did my testing using 4x5 film to save a few $$. 4x5 and 8x10 are the same film just cut to different sizes. It is my understanding that 35mm film is different and as the late Fred Picker used to always say "different is NOT the same."

Extremely careful workers will tell you they purchasse a years worth of film, test it for film speed then forget it until the next year when they repeat the exercise. I've never been this anal myself, but if I were making my living doing photography rather then being a serious amateur, I would certainly follow this procedure.

Good Luck and as always...YMMV

[Ken Lee]

"...will the test be reliable also for large format or the fact that I change camera, lens and format would make the tests useless?"

The films are different, the lenses and shutters are different, and the light meters are different (if you use a different meter in-camera versus for large format). But given that each lens and shutter is off in its own unique way at each shutter speed and aperture, I'd be surprised if all those differences didn't cancel one another out, making it possible to test with 35mm.

However - You are testing not only to determine film speed, but developing time. We develop sheet film differently than roll film; that is a meaningful difference. If you want to test your sheet film, test with sheet film, as you have already done. I still follow good ol' Ansel.

[RichardRitter]

Test with the 4 x 5 film the base fog is different on 35 mm film.

[D. Bryant]

Hello. I'm going to run tests fp4+, hp5+ and delta 100 for the correct sensibility, n+1 and n-1 developments (procedure as described in A.Adams books). I usually use 4x5 and 8x10 formats for my photos, but I would like to use 35 mm films for the tests, because it's cheaper. I would use the same developer I use for developing large format sheets.
My question is: will the test be reliable also for large format or the fact that I change camera, lens and format would make the tests useless? :confused:
Luigi
If you are really interested in testing film I would stronly suggest using Phil Davis's BTZS method of film testing. You will save enormous amounts of time and money in the long run. And in the process really learn how your materials perform.

Don Bryant

[Brian Ellis]

The best way IMHO is to let The View Camera Store do the testing for you. It cost $35 (last time I looked) and you'll receive more information faster and easier than if you do it yourself. The last time I did my own zone system testing I went through a box of 25 sheet film to do it, partly because the light kept changing (I don't believe in doing zone system testing indoors for outdoor use, just a quirk I guess).

But if you want to do it yourself, don't use 35mm film. If you're going to go to the time and trouble of testing 3 different kinds of film you may as well get it exactly right rather than ball park. You can get a ball park ISO just by reducing the manufacturer's ISO by one stop and you can get ball park development times just by reducing the normal time by about 20% for minus 1 and adding 25% to the normal time for plus (or maybe it's vice versa, I forget).