Pre Flashing Film - Anyone Do It?

[Colorado CJ]

As winter is here, and many days have very flat light, with white skies, and snow on the ground, I am wondering if I should try to pre-flash some film.

Has anyone done this, does it really make a difference in such low contrast scenes? What are the positives and negatives of pre flashing? Lastly, what is your technique when pre flashing film?

Here's one example of where I might like to try pre flashing. I don't know what exactly it would do, or if it would help, as I have no experience with it. This scene spot metered between 14.5 EV - 16 EV.

https://farm6.staticflickr.com/5648/23358475196_1a558c36a2_o.jpg (https://flic.kr/p/BA7hSY)Winters First Snow (https://flic.kr/p/BA7hSY) by Andrew Marjama (https://www.flickr.com/photos/55229792@N03/), on Flickr

[Jac@stafford.net]

Preflashing lowers contrast. Is that what you want? Grey snow?

[Michael E]

Or more detail in the deep shadows? That's the reason I use it sometimes.

[TrentM]

I've pre-flashed, as described in Ansel Adams' "The Negative". It is a method that boosts shadow detail in high contrast scenes to a higher zone (the norm here in south FL). For low contrast, I would expose for an N+1 to create more separation between grey scale tones and boost pure white (zone VIII+).
For your beautiful snow scene like your original post, with very low contrast , you could add sparkle to the snow by slightly over-developing the film...but be careful. you might want to go out and shoot several sheets under your low con conditions and try raising development time by a few percentage points for each. If you are printing in a traditional darkroom, you could them determine the correct expose on your selected paper

[Colorado CJ]

I definitely don't want grey snow. I guess I had it backwards what preflashing does.

I'll try some N+ development times and see what I can come up with.

Just trying to get a little more "pop" from these very low contrast scenes.


It does sound like pre flashing might be a good idea when the skies clear up and there is a high contrast range between the snow, shadows and sky though.

Looks like I need to reread "The Negative" since I got it completely backwards of what preflashing does.

[Michael R]

Exposure of film (or paper) to non-image forming light (pre-exposure/flashing, flare) raises the densities of low exposure areas, but decreases contrast in those areas. Generally speaking it does the opposite of what you want when you are trying to maximize contrast.

Nice photo, by the way!

[Jerry Bodine]

[QUOTE=Colorado CJ...Looks like I need to reread "The Negative" since I got it completely backwards of what preflashing does.[/QUOTE]

You'll find it under "Pre-Exposure" in the index (p. 119 in my copy). Read it very carefully, as there are important precautions to heed.

[Jac@stafford.net]

Or more detail in the deep shadows? That's the reason I use it sometimes.

An amusing tip: if your image doesn't have sky in the frame, shoot with a blue filter. The shadows will fill as if you used a small second sun for fill.

[Jim Jones]

For sunlit snow, a red filter deepens shadows which boosts texture and contrast a little.

[Drew Wiley]

I never flash except once in awhile to correct a color cast in shadows using color film. It muddies up the shadows, though some people might still do it. I'd rather
just use a film properly matched to the anticipated contrast range of typical scenes, then develop as needed for printing contrast. In this case, just plus develop.

[Doremus Scudder]

Just for the sake of completeness, we should mention that pre-exposure is a useful tool for transparency films. It was the only way to tame contrast a bit on the now-discontinued Kodachrome (which was what I used it for back in the day) and is still a viable technique for chromes. Of course, pre-exposing transparency film affects the highlights, not the shadows, yielding more detail, but less contrast.

For negative materials, it is less useful, but can yield good results with films like TMY; it turns its straight, steep toe into a gentler, curving slope, more like 320Tri-X. For those that shoot roll film, I would think that pre-exposure would be used more often for the occasional contrasty scene with lots of deep shadows, since the frame is going to get over-developed anyway (i.e., not receive an N- development, but get N with the rest of the roll).

Best,

Doremus

[Drew Wiley]

Exactly why I don't like Tri-X, and prefer TMY for what is does in the first place. But don't you have that transparency comment backwards? For instance, flashing
for the equivalent of Zone III in a chrome has sixteen times more effect down there than it does up on Zone VII, which is just about the dynamic range of most chrome films otherwise. That is exactly why one can pre-flash to color-correct a shadow without having much effect on the midtones and highlights, which is something I find myself sometimes needing to do in scenes with strongly mixed lighting, some in open daylight, some in deep blue shade. In this respect, it makes no difference whether the color film is neg or chrome, though the degree one chooses to flash might. Basically, I gave up trying to do it with chromes, because to have any significant effect, you had to flash for Z IV, which inevitably gets the midtones muddy. Color neg has more latitude, so you can flash it further down, without causing much trouble further up. Now my biggest problem seems to be remembering which kit I left my flashing attachment in, for flashing in the field of course.

[dave_whatever]

Surely pre-flashing impacts primarily on the areas of film otherwise getting the least exposure, its not one of those things where transparency film does the opposite of neg film.

I've often fancied trying pre-flashing velvia for contrasty situations, but never remember to try when I'm actually out shooting.

[Andrew O'Neill]

I pre-flash to open up shadows and reduce contrast.

[Doremus Scudder]

... But don't you have that transparency comment backwards? ...

Yup, got it backwards. It's been way too long since I shot any transparency film at all I guess. I was conflating a bit with pre-exposing paper. After digging through the recesses of my memory, I remember now that I would expose transparency film for the highlights and flash for the shadows if I thought they needed a bit of support (and didn't want them to turn out jet-black). Sorry for any confusion...

Point being, still, is that contrast controls for transparency film are limited and pre-exposure can be a useful tool there. In most other instances (when shooting film, I mean), there are better options.

Best (and thanks for keeping me straight!)

Doremus

[Kirk Gittings]

I never flash except once in awhile to correct a color cast in shadows using color film. It muddies up the shadows, though some people might still do it. I'd rather
just use a film properly matched to the anticipated contrast range of typical scenes, then develop as needed for printing contrast. In this case, just plus develop.

That has been my experience too. A couple of decades ago I did some testing with it on Chromes. While it did boost shadow detail. I found it muddied the shadow tones, but maybe I did not experiment enough with it to master it.

[Michael R]

Not sure if it will help, but to visualize the effect of non-image forming exposure on negative materials without getting into sensitometry, attached is an illustrative diagram of what it does, with some relative Zone markings for ZS users.

142991

[Drew Wiley]

The problem with chromes is that to have any appreciable effect, you are going to muddy the details somewhat right into the midtones. With most neg films, either color or b&w, you can flash for a lower zone. I still don't like to do this for black and white film, however, because crisp shadow separation is often the name of the game for me. I'd rather solve the problem with unsharp masking. Minus development isn't always a preferred option, because it compromises midtone microtonality. So like I already hinted, I use this tool mainly for correcting shadow casts with Ektar color neg film in split lighting scenes, at least where I don't want the blue in the shadows. Sometimes I do. Otherwise, if it's just a contrast control issue, I unsharp mask for this film too. But it's fun to learn all these techniques, just in case you need some special tweak someday.

[john borrelli]

Pre-flashing may have given you more detail in the trunk of your foreground tree but it could have negatively affected other parts of the image.
I am not sure if that would have improved the image overall, as the image has a very pleasing composition and natural feel as it is. Sometimes changing how something is reproduced will negatively effect something else that you liked about the image in the first place.

[bob carnie]

I have flashed film in development - lots of strange occurrences depending upon main exposure of film and length and strength of flash, probably of no value to this discussion.

one thing I have picked up is that with flash a huge flattening of the scene always happens and I am sure this is the effect some are talking about.