Film ISO speed test question

[brian steinberger]

I just ran the classic ISO speed test for 4x5 TMax100. I got an ISO

of 64. Now, I shoot Tmax100 in 120 as well. Do I need to re-do the

test for 120 Tmax100? I'm gonna be using the same RS developer for

the 120. I though 4x5 sheet film is thicker than roll films. Does

this make a difference? Thanks

 

Brian

[d_purdy]

In my tests they come out about the same. Go ahead and start shooting but

shoot a zone 1 test on one frame of the first couple rolls. And a zone 7 or 8 for

processing test. You are definitely in the ball park.

[dennis_oconnor3]

I agree with Dennis, you are going to be in the ballpark... But, given the variables in shutters, glass, and emulsions, doing the testing over witht he MF camera and lens you are actually using may be, illuminating...

 

denny

[pgwerner]

I don't know much about large and medium format photography, but I'm presuming the

4X5 and 120 films are being shot with different cameras. I believe the development

process is somewhat different as well, since 4X5 is in sheets and 120 is in rolls. If so, I'd

recommend by all means retesting, and if you want to be really thorough, retest for each

lens.

 

Exposure tests are absolutely relative to your camera/lens setup, not to mention the

idiosyncrasies of your own film development process - a reason why I take manufacturers

recommendations and other people's test as only a starting point.

 

Peter