View Full Version : tmax 100 and f stops

1-Sep-2008, 10:23
if i shoot a session with 4x5 and got a reading of f8 but actually shot f8.5 should i be worrying?

Ron Marshall
1-Sep-2008, 10:34
If by f8.5 you mean that you are underexposing by a half stop, then your negs will be a bit thinner, and you may loose a bit of shadow detail.

1-Sep-2008, 10:45
You'll be more than fine...don't worry.

Andrew O'Neill
1-Sep-2008, 11:16
What EI did you use?

1-Sep-2008, 13:43
If you use an EI based on the ISO or ASA standard (ie manufactures ISO) you have NO latitude for underexposure! Those standards give the LEAST exposure that produces an acceptable image.

If you shoot at IE 50 or 25 you will be fine.

Eric Leppanen
1-Sep-2008, 14:20
Assuming your metering is spot on, it comes down to what EI you used and whether you are printing traditionally or digitally.

If you used EI 100, then your negatives will be slightly thin and you will lose some shadow detail. If you print digitally then you should be able to selectively recover enough of the shadow information to produce normal looking prints. If you print traditionally then you may have to live with slightly dark shadow areas.

If you used EI 80 or lower, then your negatives should be fine.

Brian Ellis
1-Sep-2008, 18:35
The short answer is that PV's answer is right. The long answer is that to really answer your question we need to know more about the photographs you made and how and what you were metering to arrive at f8 as the proper exposure. But the only time a half stop underexposure with b&w film is a real problem is if at f8 (in your situation) you were right on the borderline of having detail or texture in the darkest area of the scene in which you wanted detail or texture. In that case a half stop underexposure will likely cause you to lose that detail or texture. But the odds of being right on that borderline are very slim so you almost certainly don't have to worry about anything, you should have a very printable negative assuming everything else was done correctly.

As an aside, I don't understand the answers you received that talk about the film speed you used. If you were using the right film speed for you (i.e. you've either tested to determine your personal film speed or you've been lucky with a guess) then it doesn't matter whether that speed is 50, 80, 100, or 150, your half stop underexposure is as likely to create a problem of some kind with one number as it is with another. Stated another way, exposing film that for you has a speed of 100 at 80 will solve an underexposure problem only because you're using the wrong film speed (i.e. you're overexposing your film). And while that may solve the underexposure problem (assuming there is one), it may create other problems in the highlights. And if 50 or 80 is the correct speed for you then obviously exposing at 50 or 80 doesn't help your underexposure problem. So I don't think the speed you were using matters as long as it was the correct speed for you. And if you've been using the wrong film speed then you'll have a variety of other potential problems.

1-Sep-2008, 19:43
i rated at 100 on my meter but have not developed yet just noticed that the aperture was off when i was done

Allen in Montreal
1-Sep-2008, 19:55
i rated at 100 on my meter but have not developed yet just noticed that the aperture was off when i was done

1/2 of one stop I take it.
It does not sound like you have gone through the exercise of personal film speed and are using the recommended times/speeds only.
Process one sheet, re-evaluate from there.

1-Sep-2008, 21:31
i rated at 100 on my meter but have not developed yet just noticed that the aperture was off when i was done

Film marketing promotes increased speed as "better," so it is not surprising that manufactures have adopted a system that rates the film based on the minimum exposure for an acceptable image (ISO or ASA). This rating gives Zero stops of underexposure latitude (by definition) and about 6 stops of overexposure latitude. You could rate the film at EI 25 and get 3 stops of latitude on either side.

Michael Alpert
2-Sep-2008, 09:04
This is a question that only a newcomer to photography would ask. The answers so far have been fine. I want to add that this question of proper exposure is the same for all formats of photography. In this area of concern, you do not need to think any differently than you did in 35mm.

The only way to find out what you want and need is to work at it. That is, don't be afraid to make mistakes and to go in wrong directions. But keep track of what you've done, and make rational adjustments. Take heart. Everything that is technical becomes more understandable with more experience.