Pre-Flashing in the Camera

[Fragomeni]

Hi all. I'll be taking a close look that AA's The Negative tonight when I get home from work since it covers this concept to some degree but I wanted to make this post in hopes that some of you could offer your insight and experieces. I've worked with paper negatives for a long time and have a process that works very well for me which does nto require flashing paper. I've never really needed to flash paper so I've never really learned much about it. I'm working with the new Harman Direct Positive Paper and from what I understand so far, pre-flashing is one of the better methods at controling the contrast of this paper. Specifically, I'm hoping that someone can go over how to flash in-camera. I've read threads and aritcles in which people discuss pre-flashing in camera to zone III or II and so on. I'm very green with all of this flashing business so I'm hoping that someone can offer an explanation of how all of this works and how to accurate determine how much of a pre-flash the paper should get to achieve whatever you're going for. I hope this isn't a repeat of too much thats been covered already. I tried to find my answers in past threads and nothing entierly covered the concept in whole and Google searches just turn up irrelevant information. Any insight (or links) would be hugely helpful! Thank you!

 

[BrianL]

A good source for pre-flashing is AA's book on the Polaroid camera. He goes into it quite expensively in it as it workd so well with their film. I tried it with mine Polaroid films and found with some practice it worked well. The key is to experiement and keep records. I had a scrap book that included the photo, pre-flash material used and settings for lens and time. A good starting piece I found was a plastic milk carton that had a uniform transluceny.

I've never tried it with regular film. The camera would need double exposure ability to work.

 

[Fragomeni]

Thanks for the tip on the AA book. I didn't know about that one. I just ordered it from an Amazon used seller now.

 

[williamtheis]

a way to think of it is as follows:
lets say you add a zone II pre exposure (film fogging!) through a piece of semi translucent plastic (that you metered as Zone II). Values on the negative at zone I will get to be Zone III (I+II=III) or 3X the density. Values that were at zone IX will not change by the same relative amount (IX+II=XI or 9 becomes 12) or becoming denser by 12/9 = 1.3X. Shadows gain density but highlights are barely affected at all

Clearly nothing will be below Zone II so you will have to print through this "base plus fog" yielding longer exposure times to do the printing. However notice all that shadow detail which was lost is now visible!

naturally this assumes that you don't block up the zone IX (9) with the film you are using... which is not a problem with a film like TMAX but may be a problem with TriX

 

[Fragomeni]

Can you go a little more into that? What I don't understand is exactly how you're measuring this Zone II exposure. I understand that the purpose of shooting through the semi-translucent plastic is to get diffused even light to fog the film/paper but I don't get how you're metering the material and coming up with the exposure and how that relates to Zone II. Sorry if im over complicating it.

 

[doughowk]

Ralph Lambrecht has a chapter on pre-flashing (pre-exposure) in his "Way Beyond Monochrome". I picked up a white balance filter designed for the digi-snappers, and it gives an even exposure across the film/paper neg.

 

[ChuckP]

The Wallace Expo Disc site has some info: Dead Link Removed

 

[williamtheis]

I have a piece of translucent material I think I got from an Art Supply store which I use in my gel filter holder in place of a gel filter. almost anything works as long as it is uniform.

using my spot meter I place the piece of material over the lens tightly and point in the direction that the camera is pointed, meter for exposure settings for zone II (or zone III if it's super contrasty) and perform the exposure.

NOTE: this method does NOT depend on doing pre exposure first so one thing you can do is choose to expose later when you get back home under more controlled settings! but if you are worried about keeping track of which holders to add the pre exposure to when you get back, then by all means do the preexposure before the normal exposure.

also NOTE: do not over expose the highlights.... you will be placing the highlights in this case rather than the shadows. This is just the opposite of placing the shadows on a zone that gives detail since you are relying on the pre exposure to make the detail... so place the highlights on the most your film can handle, which for TMAX is around zone X... then when you print, you will have to add exposure to "print through" the extra density of the shadows due to the pre exposure and this added exposure will add the necessary details in the highlights

this is actually easier to do than to explain....

 

[piu58]

I did some preflashing of film sometimes to modify the contrast. I did not use a translucent sheet but used another method.
I looked for a uniformly illuminated area in the shadow, mostly a wall. Without trowing a shadow on the wall I measured the f/stop-time-combination. I used a f/stop as wide open as possible and selected a time 3 or 4 stops shorter as the reading, for getten an zone II or I preflashing. I put the lens some centimeters from the wall and adjusted the skale to infinty and took the preflash photo. The real photo requires two or one steps less light.
This works quite well. It helps if you have very short times in your camera. My Rolleiflex ends with 1/500.

Example: I want (the most used) zone-ii-preflashing. I look for a wall in the shadow amd measure 1/30 f/4. I select 1/250 f/4 for preflash. The reading for the real scene may be 1/60 f/16. With zone-ii-preflash I have to use 2 stops less, for instance 1/125 f/22. This helps the higlights - they get less light and come into an easier to print area. The shadows get less light but this is compensated by the preflashing.

 

[DREW WILEY]

A gel film holder over the lens is an easy way to slip in a little square of diffusion
mylar. It takes a bit of experimenting to get the correct level of pre-exposure. I've
always found the results of flashing to be disappointing. The shadows get raised a
bit but are otherwise muddied up. I'd much rather control the shadows by using a straight-line film and split printing on VC paper, or perhaps unsharp masking. That
way shadow detail isn't compromised and things remain crisp. But it's fun to experiment with all these techniques.

 

[piu58]

The shadows get raised a
bit but are otherwise muddied up.

Preflashing works best if you develop the film to N+1 or N+2. For contrasty scenes you use preflashing, for less contrasty you don't. Poor man's zone system.

 

[Ronald Moravec]

I know wedding guys that preflashed 35 mm rolls to get more detail in a black tux.

You flash experimentally until the base just gets some fog, then back off a little.
It will be around 1% box exposure.