Flash Film

[sully75]

Can you flash film the way you do paper for low light photography? Does it work well? I'm just wondering about something like TMAX 400, could I flash it for use shooting in dark bars? This would be for small format use, most likely.

[vinny]

yes.

[Mark Woods]

Please read Ansel's book, The Negative.

[Doremus Scudder]

Flashing film is possible.

The point of flashing film is to give extra exposure to the lowest shadow areas to raise their values enough to print with some detail. The technique is to give a Zone I or II exposure to the film to overcome the exposure threshold and give the film a very slight overall fogging. This then allows shadow values, which would ordinarily have not registered on the film to be recorded.

The mid-tones and highlights above about Zone IV are not much affected. Separation in the shadows is reduced.

Think of it arithmetically. If Zone I is 1 unit of exposure and every Zone above that a doubling, you get the following:

Zone 1 = 1
Zone II = 2
Zone III = 4
Zone IV = 8
Zone V = 16
Zone VI = 32
Zone VII = 64
Zone VIII = 128
Zone IX = 256

Giving, say, a Zone II exposure as a flash then results in the following (adding 2 to the exposure units above):

Flash exposure = 2
Zone 00 = 2.25
Zone 0 = 2.5
Zone 1 = 3
Zone II = 4
Zone III = 6
Zone IV = 10
Zone V = 18
Zone VI = 34
Zone VII = 66
Zone VIII = 130
Zone IX = 258

A quick comparison shows that shadows are raised (Zone 00 and 0 will now be recorded on the film), but at the expense of separation (from Zone II to III is now less than a doubling and lower Zones are even more compressed) and that the values above Zone IV are affected very little, with the effect decreasing as the exposure increases (Zone IV is raised by 20%, Zone V by about 9%, Zone VI by 7.5%, etc.). What you have done is squeezed some extra low shadows onto the film by sacrificing separation. And, you'll have to print through the fog to get a real black, so at the printing stage, Zone 00 will be just barely more than a black, Zone 0 as well, Zone I significantly higher than before, Zone II moved up to the "detailed shadow" point where Zone III usually is, and so on.

If you are looking to get some extra detail in the shadow, and can't use a slower shutter speed (as in your dark bar situation), then flashing will help some. You'll lose separation, but get more detail than otherwise. It works well in conjunction with push-processing too sometimes.

I usually flash to a gray card in even light (when I flash at all these days). There are lens-cap diffusers that work well with in-camera meters too. Experiment with Zone I and Zone II flash exposures (minus 4 and 3 stops from an average reading respectively if you're not familiar with Zone System parlance). Meter the card (or any evenly lit surface), move in close, focus the camera at infinity, so the image is out of focus (you don't want any texture detail from the card you are using) and then make the flash exposure.

I know this is the LF forum, but flashing works well with roll films as well. It's easier with sheet film and cameras that allow the shutter to be cocked separately from the advance mechanism however. You can flash a number of sheets in advance if you like and have them on hand.

With roll films, you can flash and entire roll in advance. If you do, you have to mark the film leader exactly in register with something when loading. Go through the roll giving your flash exposure to each frame and then rewind the film (making sure not to rewind the leader all the way if it's 35mm). Then reload the film using your mark to get the film in the exact same position. You can then shoot away.

Hope this answers your question,

Doremus

[rfesk]

Thanks for the discussion.

I plan to copy some old slides onto B&W film and thought it would lower the contrast some but maybe my thinking is wrong. Need to study it more.

[QUOTE=Doremus Scudder;881560]Flashing film is possible.

The point of flashing film is to give extra exposure to the lowest shadow areas to raise their values enough to print with some detail. The technique is to give a Zone I or II exposure to the film to overcome the exposure threshold and give the film a very slight overall fogging. This then allows shadow values, which would ordinarily have not registered on the film to be recorded. ETC

[sully75]

Doremus,

Thanks for that. I hadn't thought about the registration issue. That seems pretty difficult to pull off...does it work in practice? I have a hard enough time getting the film loaded in a Leica...

[Doremus Scudder]

I don't shoot 35mm anymore (My Nikons are rusting away in a closet somewhere...), but I used to just load the film and then make a mark on the film back with a Sharpie where it lined up with an easy to identify spot on the camera interior. Then, when reloading, I just put the mark back in the same place. That seemed to work well for me. Of course, you have to make sure the advance mechanism is in exactly the same configuration too.

BTW, if I were copying slides to black-and-white, I would be using T-Max 100 (too bad Panatomic X isn't around any more...) and do exposure and development tests with a slide-duplicating set-up and consistent lighting. In other words, I would control contrast by development. Zeroing in on the exact combination can be tricky, since a change in development changes the effective film speed, but once figured out, you would then have a foolproof set-up.

Best,

Doremus

[Renato Tonelli]

Kudos to Doremus for posting a well thought out explanation.

Pre-flashing and post flashing are part of the normal tools in cinematography. There are proponents of pre-flashing as opposed to post-flashing. In my experience, I have preferred post-flashing; that is, flashing the film after it has been shot as I feel it gives me more control.

In 35mm still photography you will absolutely need (as has been pointed out) a camera with good registration or one capable of double exposure. I have been able to do exactly what you are trying to do with a Pentax LX, which has double exposure feature.

[sully75]

Thanks guys.

Renato, do you take a picture and then immediately flash it? That seems kind of clunky if you are shooting in some sort of action environment.

[Renato Tonelli]

No. I flash it later. For some reason I thought that was what you wanted to do.