underwater photography

if anyone is familiar with underwater photography, hoping you can explain

reason for this. i have been using a simple compact canon camera for snapshots

while scube diving. but colors were always flat and mostly with blue tone.

(true color of the fish didnt come up). a fellow diver/photographer told me to

change the setting on my camera to exposure -2 (minus two) and force flash. i

now have brilliant color. i just want to understand why going to minus two

helps.. as i would have thought more exposure and more light would show more

color. any thoughts?

I'd suggest you find a good book on the subject. Water removes the red component from light in about 15 feet of of depth. This means that mostly blue light reaches below this point. The only real fix is to use flash or to shoot in shallow water.

Well, when you underexpose and use a flash, 2 things are happening:

 

1/ Your subject is being exposed by the flash. The underexposure only affects the background. Because this is an artificial light source that is close to the subject, the reds are not absorbed by the water and you get the "true" vibrant colors.

 

2/ The background is being exposed by the aperture/shutter combo you choose. By shooting at 2 stops under, you are essentially darkening the water, making it deep blue, tending to black. Depending on the color of the water, you might try underexposing by 1 or 1.5 stops as well.

 

Hope that helps.

 

Vandit

Do a search on the diving sites for underwater filters. I can't recall the filter I used to use, but it would warm up the shots. It's not like an A2, it was actually designed for underwater use.

www.magic-filter.com (or it could be www.magic-filters.com).

 

Google for Magic Filters, and you should find it.

 

They work quite well, but the problem with any fixed filtration system is that it will introduce a cast if used too shallow or too deep. Still, at $30 or whatever the MFs cost, it is a lot cheaper than spending $1000+ per strobe+arms+sync cord.

 

Vandit

I believe the filter might be the cc30r, at least that's the one I remember. The best way if you want consistantly exposed pictures with true color is flash. It also freezes the subject helping greatly with swimming fish and your body that's being thrown around by the currents. Getting the flash up and away with an arm is important as that helps relieve any backscatter that may reflect off particles in the water back into your lens...

Any underwater camera can only be used without flash down to some 2-5 meters, depending on the strength and angle of sunlight and cleanliness of the water. Below that, you must use flash to get decent pictures. Strong orange filters help compensate for the blue cast but when you go deep enough, even that does not help.