Film color preflashing

[Domin]

Recenty I got an idea - film preflashing as means of balancing color. I was recently shooting some slide in available light and xprocessing it. As one could cross exaggerated color casts from both tungsten and fluorescent. Especially the latter.

Does it make sense to try to correct it with preflashing with colored light? I suppose I could get some speed boost instead of loss from balancing filter and lowering contrast wouldn't hurt.

 

[Mike Wilde]

It might work, but my only experience with pre flashing is where you want to reduce overall contrast. In your scheme you woul 'anti bias' the lighting to keep the overall look as neutral, but the light illuminating the areas of interest in the frame would then not quite match up. as most scenes are not evenly lit.

 

[keithwms]

Interesting idea, show us where it takes you!

 

[Q.G.]

Preflashing works by helping to lift the 'dark' bits above the threshold of 'developability' by adding just that tiny bit extra that they need, while not being strong enough to noticeably affect the other bits.
So it might work, but for the dark bits only. Else, i.e. with more power to it, you will probably blow out the highlights.

But worth a try.

 

[Domin]

The idea is to preflash with color witch is lacking in the lightining, so what would blow is what would blow as well when using color balancing filter. Tungsten lacks blue so I want to preflash with blue, not whole spectum.

 

[L Gebhardt]

Try it and let us know.

My prediction: It will mostly affect the color balance in the shadows. As a percentage of the exposure the preflash will be negligible in the highlights. Could make for an interesting effect.

 

[Tim Gray]

I think you should definitely try it. Assuming you are going to preflash some daylight film some blue light and then shoot it under tungsten, I wonder how it would compare to shooting daylight film indoors and trying to compensate in the printing stage with a color filter?

 

[Q.G.]

What will be interesting is to see the colour cast.

Usually, a film only sees blue if a bit of the subject is reflecting blue.
If blue is lacking in the incident light to begin with, blue things will not be recorded as blue. Add a bit of blue to the bit of the film where the blue bit is, and the colour will reappear again.

But put a deep red thing in the scene. The blue recorded by that bit of film will be almost nothing, if anything at all, whether there is blue in the incident light or not.

But a preflash isn't selective like that, and will give everything the same amount of (extra) blue.

 

[Domin]

Try it and let us know.

My prediction: It will mostly affect the color balance in the shadows. As a percentage of the exposure the preflash will be negligible in the highlights. Could make for an interesting effect.

Now that you mention it I see that preflashing with color is a recipe for crossover. When I was thinking about the curves I forgot that there is log exposure on horizontal axis and not linear exposure so preflash changes curve slope and not just shifts it.

So there are good chances that it would make color balance of a neg even worse. However I was writing about cross processing a slide in the first place so I might be not that much tu ruin in the first place.