If you put a coloured gel on your flash and then take a photo, the foreground of your image (everything lit by the flash) will be the same colour as the gel.

What if you put an opposite coloured gel on your lens to cancel out the effects of the gel on your flash? Now the foreground of your image (lit by your coloured flash) will be back to normal colour, but your background (ie NOT lit by flash) will be tinted by the effects of the gel on your lens.

So you could put a red tint on you flash, a blue tint on your lens and end up with a blue background.

Of course, some experiments will have to be made to find the right gels to use together. Oh - and it might be easier just to use photoshop...
-- MikeyTheBikey, May 06 2005

Colored Flash http://www.alienbees.com/filters.html
[DrCurry, May 07 2005]

I don't know if it would work quite right, but the experiments might come out looking good.

Thinking about it, any background light would still be filtered through the (say) blue lens, so your subjects would still come out looking blue.
-- Detly, May 06 2005


You used to be able to buy paired filters for exactly this purpose. I'll see if I can find a link.

[later: nope, can't find anything] I guess it was fairly obscure.

For those querying whether this would actually work and, if so, how, the answer lies in the the word 'tint'. The effect is generally done with fairly weak filters resulting in pastel tints.
-- st3f, May 06 2005


Look into painting with light. Some beautiful work has been done with long exposures on color film, using colored filter covered flashlights to illuminate chosen detail in different colors.
-- normzone, May 06 2005


As a gaffer in a previous life I can tell you that you've confusd me.
-- SpocksEyebrow, May 06 2005


Great, like white spots weren't bad enough...
-- finrod, May 06 2005


Another fun thing to do is get some IR film (Ektachome-IR or Kodak HS-IR) put a #85c filter on your flash and take pictures in low light. Very cool results.
-- Jawzx, May 07 2005


I've taken a lot of photos recently of subjects lit by both artificial and natural light, with color balance issues just like the ones you seem to be after.

But when I used the flash unit, it overwhelmed both. I would suggest modifying your technique: use two flash units, and just put the filter/gel on the one lighting the background. But far from being half-baked, I would point out that this is a well-established lighting technique.
-- DrCurry, May 07 2005


DrC that works fine indoors. This is more of an outdoor technique where you are using the flash to provide fill on a subject against a distant background.
-- st3f, May 07 2005



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