Polarizing Filters

[mccabejc]

When there is a lot of particulate matter in the water, with light reflecting off it, wouldn't a polarizing filter help to clear up the photo, and make the water look less murky?

 

[Charlie99]

It's easy enough to check out, even if you don't have the proper polarizing filter for your camera.... just take a pair of polarized sunglasses with you next time and rotate them around while looking through them.

The couple times I check this out, there didn't seem to be much polarization of the underwater lighting at my divesites.
This wasn't very surprising considering that an overcast day reduces the polarization of sunlight.

 

[Gilligan]

When there is a lot of particulate matter in the water, with light reflecting off it, wouldn't a polarizing filter help to clear up the photo, and make the water look less murky?

I don't know if it will make the water look less murky but I have a polarizer filter for both my camera and my underwater housing so that I can use the housing topside.
I found that the polarizer makes a lot of difference in photos with a lot of water and/or sky in them.

The polarizer filter makes a big difference when shooting down at very clear ocean water as it allows you to see the reef below in shallow water.

I think most prosumer digital cameras require a circular polarizer filter which is one you rotate after threading it on in order to get the optimum results.

I found a 3 lens kit on eBay with the step-up ring for my Olympus camera at a very cheap price.

I took this photo on Guam with a polarizer filter on my camera (not the housing). I'm sure it made a big difference in the sky and the reef.

 

[MacHeath]

Polarisers certainly can help, but as others already pointed out it will depend on:
The cloud cover (more cloudy equals more diffuse light equals less polarisation).
The suns angle, when the sun is directly overhead, I thinke the effect will be minimal.

http://lfw.pennnet.com/Articles/Article_Display.cfm?Section=ARTCL&ARTICLE_ID=216639&VERSION_NUM=2

Also some animals like Cuttlefish actually use and see polarisation, so you might get some interesting pictures of them..

 

[f3nikon]

When there is a lot of particulate matter in the water, with light reflecting off it, wouldn't a polarizing filter help to clear up the photo, and make the water look less murky?

To answer that question (which is a good question), can a polarizing filter clear up snowflakes falling to the earth? When using strobe lights, the answer is no, the flakes with still be in the picture. Particulate matter in the water, like snowflakes are real objects that refect light. A polarizer can bend the light to hit the film plane at a different angle, but the light from the particulate still gets on film, and the light bounces at different angles from different particles. And the spot where the reflections were reduced, you will see an out of focus spot.

This is the reason why most of the U/W photo pros use extra long strobe arms to "bounce" the light at angle away from the lens/film plane. With that extreme angle comes some, very extreme shadows, that is the reason for using a multi-strobe setup.

This is the same principle as reducing "red eye" or taking an on camera flash pictures, with a mirror behind your subject.