Pre-exposing film for decreased contrast ?

For the most part I shoot primarily in heavily wooded areas, often in bright sunlight with deep shadows. I prefer to create images with bright open shadows, so I am constantly fighting against high contrast. Up until now I have been primarily concentrating on film compensation development and latent image bleaching to help create the images I seek.

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However, over the years I�ve read about, but not tried, the technique of pre-exposing sheet film prior to field exposure, presumably to decrease overall contrast of the film (AA �The Negative� p119-123). I�m not excited at the thought of discovering yet another way of destroying film, I already have quite a few successful methods already :-)

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So I am interested in hearing from anyone that uses this technique, your successes or failures, or any tips you might have that would help me.

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TIA - doug

It works fine. The basic idea is that if Zone II has 2 units of light

and Zone VII has 64 units of light, a uniform 'fogging' exposure of 2

units will add 2 units right across the scale. The difference is that

Zone II gets elevated to Zone III (2 units from scene plus 2 units

from fogging exposure) but Zone VII hardly shifts at all (64 + 2 =66

units).

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The fogging exposure can be made before or after the main exposure

(so, if you can keep your film seeparate in the field, you can always

add the extra exposure in your darkroom). You can use either your

enlarger or a pre-exposure device which is essentially like a

diffusor or you can fill the frame with a grey card and expose it to

the grey card. Essentially, what you end up with is a deformation of

the characteristic curve by lengthening the toe. You get similar

deformations of the curve from flare.

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The downside is that you lose local contrast in the shadows. That is,

you hold a longer scaled subject but the local contrast in the

shadows decreases (since lengthening the toe basically reduces the

slope of the toe part of the curve). I guess its an individual

aesthetic decision as to when you would use it. I would suggest this

as a tool to use when you need to hold a longer scale but local

contrast in the highlights is crucial.

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Your goal of open, luminous shadows suggeests this is an area of

crucial local contrast. However, a lot depends on how you visualize

it. Shadows can be open and luminous but soft, which suggests a

reasonable placement (fairly high on the toe) and something like a

fogging exposure. Or they can be open and luminous but quite hard, in

which case it could be a fairly high placement (to move the shadows

off the toe) and compensating development.

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Hope this helps. DJ

How about giving a compensating development process like

split D-23 a try. I too shoot in high contrast situations and this

developer allows me to read my shadows, place them around

zone 4 and still not block up the highlights.

Why not try the same thing but with your print. Flashing the paper to

bring it up to the exposure threshold is easy to do. Just experiment

with the exposrue times to get the level of detail in the highlights

and then print for the standard time. Paper is alot less expensive to

work with than film. Alot faster, too. Thats my two cents.

Polaroid used to send a diffuser with a close-up attacment kit no.583.

You could probably find one for almost nothing on ebay if you're the

adventurous type. It is a white plastic diffuser with 3 little ears

that, as luck would have it, will cling to a 67mm filter. In those

situations you're referring to, if I remember which is the hardest

part, I put the diffuser over the front of the lens and adjust the

aperture to expose for zone II. Then take it off and resume the pic

with my normal exposure. For starters try doing it both ways on the

some pic in the same film holder to see if you like the difference. 1

as normal, and 1 with the diffusion fog added.

As I noted in my lengthy question, I�m using a lot of techniques

after the film has been developed. I use graded paper and use general

overall flashing quite often, more recently latent image bleaching,

and also compensating film development. I used to use D23 but didn�t

like the overall results. Now I process in PMKpyro which is not

recommended for compensating development, but I�m experimenting with

a new technique for development (err should I say destroying film :-)

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I hadn�t considered post-exposure film flashing. Since I usually

shoot two plates, I could develop one and then consider the alternate

plate for pre-development exposure.

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thanks - doug

It makes no difference whether you preflash or post flash your film.

The poster who suggested flashing your paper makes a point, BUT, the

downside is you have to test the paper with a series of flashes (while

taking notes) in the darkroom to determine correct exposure. With

film, you know the speed, and if you've made a light reading, you know

exactly how many stops to close the lens down to reach a zone II

exposure. Moreover (this is the important bit), flashing PAPER is

helful to tame PAPER contrast, not FILM contrast. In other words,

flashing the paper will not give you shadow detail that is not

ALREADY recorded on the film. If you want to record additional shadow

density on film, then flash the film, or it's pointless. The advantage

to this is two-fold: you "get it in the negative," which means you

don't have to flash every damned piece of paper from here to eternity,

and you've got a negative with a long tonal range, which can be

suitably printed on various grades of paper for different contrast

renditions. The best, best, best, friend to the photographer, with

regard to this issue, is Ansel Adams' book "The Negative." If you

consider yourself a photographer, you should have it on your shelf. .

it will obviate several trips to photo.net for what is sometimes

conflicting advice:))) Also, Adams is ALWAYS right on technical

issues, so you can be assured that if you follow his advice, you will

have mastered your technique.

IMPORTANT!!!!!!

I forgot the most obvious thing!!!!! Flashing the paper increases

HIGHLIGHT DENSITY in the print, not shadow!!!!! Flashing paper in the

darkroom will have no effect on your shadows at all (remember we are

dealing with a negative tone process here), so my original point on

film flashing stands.

For notable examples of what flashing can do, watch "Evita" (only one

example). The DP flashed the film with several warm shades of yellow,

which gave the effect of filling in the shadows with warmth and body

to match the South American evening light he was shooting in.

Thanks for the notes Josh - I didn't think about the long term

advantage of having a better shadowed negative as opposed to always

fighting with contrasty negative printing-after-printing.

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Also you mentioned AA's book "The Negative" - I referenced that in my

original question - I'm never without it, and a 1/2 dozen other high

quality books as well :-)

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I also like the suggestion of a field diffuser that would clip to the

lens.

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I knew this forum was a good place to post this sort of question.

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Thanks Doug

Regardless of whether you can see much difference in the negatives,

there is a big difference between pre and post exposure. Pre-exposure

brings the film up onto the curve already, basically getting ready

for exposure in dim areas without them being off the bottom of the

scale. It might be thought of as "presensitizing" instead. What would

have been too low to record is now exposed at a level on the curve

where it can be captured. Post exposure will do nothing to move the

original subjects higher on the scale when they are exposed. They may

fall too low and will not register, then you add blank density over

that. Why? The idea is not just to fog the film, it is to make it

more receptive to what light there is available. However, when you

have to print through the fog, there may not be much of difference,

so it may appear similar. They idea is different, though.

With regard to pre versus post exposure, there is no difference, in

senitometric terms, between flashing before or after the main

exposure. Presensitizing or hypersensitizing is another technique

altogether wherein you bake the film in a gas (usually a combination

of hydrogen and nitrogen) to increase its sensitivity. A related

technique, often referred to as latensification i.e., latent image

intensification, involves making the least developable grains hit by

light developable. This is done after exposure but before development

by exposure to peroxide (if I remember correctly).

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As far as flashing goes, there is no difference whether the flash

comes before or after the main exposure. What matters is the total

quantum of light that hits individual areas of the negative and the

'fogging' flash basically will increase the responsiveness of the

grains to the main image light by overcoming some of their inertia

i.e., by moving them up to the toe point in the curve. This happens

even if the flash occurs after the main exposure ie.., the main

exposure records parts of the image on the curve and parts below in

proportion to light refelcted from the scene. Additional light serves

to move all of them up the curve. This can be tested by

exposing two photographic papers or films to a step wedge, one with a

flash before and one with a flash after. There should be no

difference in fog densitiy and density of each step. Cheers, DJ.

Here's a place that sells a nice diffuser to use for this purpose:

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http://www.expodisc.com/

An illustration how a pre-exposure modifies the film curve, assuming

the initial film curve (in black) was a straight line with

contrast=0.5:

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<img src=" http://www.photo.net/users/WAn/TechGraphs/PreExposure.jpg"

width=800 height=519>

</center>

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The values in brackets show the amount of pre-exposure.

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Regards,

Andrey