Weird color cast with Circ. Polarizer

C

chinadan

Member
While shooting on a sunny beach with the DVX100 in its standard configuration I would get a very pronounced color cast under certain lighting conditions (i.e. in bright sunlight but not always, probably depending on the angle of the light).

Basically, imagine the image split up in 3 segments with the lower right corner having a reddish tint, the lower left corner a greenish tint and the rest bluish.

Turning the circ. does not help and the symptoms definitely disappear when removing the polarizer.

Could this be some weird interaction between the polarizer and the prism inside the cam?

Any clues?
 
For a circular polarizer to work optimally, the light source should be at a 90 degree angle to the camera. As far as the strange coloring, perhaps this was from sunlight hitting the filter/lens directly or reflected onto the lens. What brand of filter is it?
 
It is a Kenlock Circular Polarizer

It is a Kenlock Circular Polarizer

It has served me well on my DSLR.

I have bought a 77mm BW Circular Polarizer and comapred it on my DSLR and could not find any difference in performance.

I should have tested it with the BW, but dealing with a 77mm is a pain due to the lens hood inner diameter.

Maybe I will just go ahead and buy a BW 72mm for the Panny...

I would still like to undestand the physics of this...I have a feeling that it may be indeed light coming in at a strange angle and bouncing around between the 2 filter planes of the polarizer.

Somethign tells me that this has to do with the 3CCD/Prism on the DVX100...my normal DSLR never showed any color casting...
 
Ok here goes...
I've talked to Century Optics/Schneider specifically about linear vs circular polarizers (at NAB). I work for a Century dealer.
Normally linear vs. circular is not an issue when shooting VIDEO...whether HD or SD. Basically what I was told is you can't go wrong with circular on any HD/SD/Film camera, with the ONLY exception (that I know of) being the DVX100/A...there was no explanation why other than the DSP/CCD in the DVX100/A seems suceptible to color shifting. If you can beg/borrow/steal/rent a LINEAR polarizer...see if it has the same problems. My guess is it won't...
Oh, and don't forget the obvious...Circular polarizers have to face the right direction. Oddly enough Century/Schneider the arrow points in a different direction than Tiffen!!!
Hope that helps....not sure it'll be the same with the HVX (which I'm saving for!)
FWIW hope that helps,

Brian Broz
www.llsr.com
 
Thanks Brian for the detailed info! Wouldn't the threading on the polarizer only allow for one direction to be mounted on the DVX anyway? Or am I misunderstadning what you mean by direction?

I will buy a linear polarizer and try it...I think the major negative (for photography at least) is that it messes with the autofocus...since I shoot 25p I focus manually anyway.

Thanks again for your help, I am on my way to Hong Kong to go shopping...just added the Polarizer to my long, long list.
 
You must log in or register to reply here.
Back
Top