5D overexposes with B+W polar?

[alexander_strbac]

Heloo everybody!

 

I have a weird problem with the following setup:

 

5D + 24mm f1.4 + BW circular polarizer 77mm = greatly overexposed images. It doesnt matter if I put metering on

center weighted or multi. it stays the same. Am I doing something wrong or is it the equipment?

 

A year ago I was at the Caribbean and was using a Canon 10D + 17-40L lens + Marumi circular polar. and everything

was fine. I didnt have to dial any exposure correction in or anything else.

 

Cheers

Alex

[sarah_fox]

Honestly, a camera with a circ pol on it should meter just as accurately as a camera with no filter at all. It's only the linear pols that give you the problem, because the polarized light reflects differently off of the half-silver regions of the mirror, depending on orientation. Are you *sure* the polarizer is circular and not linear? One way to tell would be to face the back side of the polarizer towards a mirror. Look through the polarizer into the mirror, and back through the reflection of the polarizer. The reflection should look black. If you can see through it, it's really a linear polarizer.

 

You might be able to narrow down you metering problems by determining the following:

 

1. Do the same exposure problems exist when the filter is removed, when shooting the exact same scene? I would suggest testing this by shooting something that doesn't have a lot of sky or reflecting surfaces in the frame.

 

2. Do the same exposure problems exist if you replace the polarizer with a neutral density filter?

 

Hope that helps. Good luck!

[howard_m]

certainly does sound like it's a linear pol.

 

if you put it on the camera and rotate the filter, are you seeing the meter move dramatically (while pointing at a non-polarized surface/scene).

[sarah_fox]

I'll just add another note here: My personal preference is to use a linear polarizer anyway. I simply adjust the exposure manually. I prefer linear polarizers to circular because they are better optically, introduce fewer problems with color, and are slightly more efficient. That said, the metering differences I see when I rotate the polarizer are not all that dramatic. Also, I don't get the AF problems that so many people claim exist with a linear polarizer. But then again, I also manage by some miracle to AF lenses slower than f/2.8, so maybe my camera bodies are exceptional somehow. ;-)

 

The up-shot of what I'm saying is that you can use the polarizer you have, even if it's a linear one. You might simply have to make adjustments to the exposure, which I would presume you would do anyway.

[ronald_moravec1]

If you rotate the filter and the exposure changes, it is a linear not circular.

 

If it a linear, rotate to the position that gives the least exposure, set that with manual exposure. Then rotate to get the

effect desired. Do not adjust exposure again.

 

Meter without any filter, add the filter and add 1.5 or two stops compensation.

 

 

A circ will work in any orientation.

[alexander_strbac]

Thank you guys so much! will do some testing tomorrow and let you know if the problem is the filter, the camera or something third (like me for instance haha)

 

Cheers!

[sarah_fox]

Ronald wrote:"'If you rotate the filter and the exposure changes, it is a linear not circular. "

 

Alexander, just to clarify, this is only true when the light reaching the camera is NOT particularly polarized. Test by aiming the camera at a white wall, not at the sky.