rdbertinot

Please explain to me the difference in lights and the gels that neurtalize them.

Thanks!! Renee'

Dave333 Loc: Forres, Scotland

Hi
Different light has different temperatures and when you take a picture under different lights tungsten, flouresent, daylight the picture can have an overall colour cast. Correcting filters were mainly for film cameras where a camera with a daylight balanced film fitted, would produce a picture with a geen colour cast (I think its green) under flourescent light. So if you had one film fitted you would fit correcting filters to take pictures under different lighting conditions or you would have to take the film out and replace it with specialist film. There is no need for them with digital cameras you just have to set the white balance setting to the type of light you are shooting under. Or you could shoot in RAW and have countless variationsof whiteblance. Called white balance because its to make your whites white. (Like DAZ).

Dave333 Loc: Forres, Scotland

Hope I haven't baffled you too much.
http://www.youtube.com/watch?v=FR-Z9UhX5Fg might explain a bit.

phys406

I have had occasion to shoot when there is a mix of incandescent and daylight - frequently encountered in museums. Surprisingly, I have found that the fluorescent setting usually gives the best (but still imperfect) final color balance.

Dave333 Loc: Forres, Scotland

If you can shoot in RAW then in post processing you can adjust the white balance with more precision either with sliders or the eyedropper and select an item that should be white. I personally always shoot in RAW you get more picture information and more chance of rescuing errors.

Kat Landreth

If you're shooting mixed light, even if you shoot RAW, the only way to really correct the color completely is to Gel the lights. For example, you might by shooting a mix of daylight and tungsten. Or, you might be in a tungsten room and want to use your flash as well. You have to use a gel for one of the kinds of light, because the camera can only truly compensate for one kind of light at a time, or try to 'split the difference' if that makes sense.

The other reason your would use Gels is if you're using film, and you only have one kind of film. For example, you might have daylight balanced film, but you're shooting in tungsten light.


Flourescent light has a green cast. Tungsten bulbs have a yellow/orange cast.

The way you gel for these is very dependent on what your light situation is, and how you're trying to compensate.

For example, if you're shooting in a tungsten room with a fill flash, you could set your camera for a flash white balance, and gel the tungsten bulbs to cancel out the yellow/orange.

Or, you could set your camera for a tungsten white balance, and put an orange gel on the flash (probably an easier way to go). This will make the light from the flash have a similar cast to the actual tungsten lights, and your camera will be able to compensate for all of the lights equally.

For a florescent light, you typically use a magenta gel to cancel out the green. Or, if you're using a flash with florescent light, you could put a green gel on the flash to make the light from the flash more light the light from the florescent bulbs, letting the camera correct all of the light the same way.

I hope that makes sense!

CaptainC Loc: Colorado, south of Denver

RAW will not help with mixed lighting as Kat explained. There is this myth out there that if you shoot raw you can correct any color issue, but it is not so. You can correct ONE. So in places with a mix of daylight, tungsten, and fluorescent, you can pick one. Now if those lights are in different areas, one could conceivably, make layers for each color, correct THAT layer, and then use masks to reveal each area, but that is seldom the case as the whole image is contaminated.

slickrock Loc: jacksonville

You can selectivly correct with brushes . Most easily with PS plug-ins.

Dave333 Loc: Forres, Scotland

As I said before light is measured by tempreture i.e Kelvin. When light is mixed it has an overall temperature. just as 2 coloured liquids when mixed will even out at a temerature and the colours will mix. This is what happens with light although the human eye can not detect it. Post procesing a RAW file in photoshop with the white balance slider can correct this colour temperature.

Kat Landreth

That's true to some extent, but there will almost always be a gradient of color concentration that gets stronger the closer you get to a light source. That's what's really hard to correct for.

Instead of the light completely and homogeneously mixing, you can end up with a photo that's yellow on one side, and blue on the other, and a mix in between, for example. In cases like this, there's then a huge range of different color temperatures that need to be dealt with and that can be next to impossible in post (unless you want to spend lot of time masking etc.)

Dave333 Loc: Forres, Scotland

This is true. Fitting gels to a lens can introduce a couple of problems, 2 extra surfaces that can get scratched and can introduce flare.

Kat Landreth

For digital cameras, I don't think you would be putting gels on the lens. You're putting them on the lights. You don't need a colored filter in the lens, since you have an in camera white balance setting.

If you had two light sources, you would gel one light to make it 'match' the other. Then your camera could use one white balance setting to deal with both lights, without the problem of a color gradient.

You would put a colored filter on a lens if you were shooting film, but you didn't have the correct film for the light. AKA you're shooting daylight balanced film but you're in a tungsten room. In that case, the alternative approach is to gel all of the lights to match the color balance of your film.