OT Polarizer Filter

Former user wrote on 5/21/2012, 6:48 AM
When I had a Canon EOS Autofocus 35mm camera, I remember you had to have a specific Polarizer filter (circular I think) because of the autofocus.

I have a Canon Vixia HF M40 video camera now, is there a specific spec for a polarizer filter for these types of video cameras?

Thanks
Dave T2

Comments

farss wrote on 5/21/2012, 7:06 AM
As far as I know there's no specific advantage to using a linear polarizer so for safety just use a circular polarizer.

The difference between the two types is not what the names suggest.
The linear polarizer has polarized light as it's output. The circular polarized has another layer that scrambles the light so that what comes out of the filter is not polarized.
You pay more for a circular polarized but you know it'll not mess up anything in any camera. The only thing you cannot use circular polarizers for is the trick of using two polarizers to make a variable ND filter but that is of no concern in your application.

Bob.
ushere wrote on 5/21/2012, 7:18 AM
hey bob, while were on the subject....

i usually use a cpl in my matte box for shooting horses, would i see any difference if i used a linear, and could i on the z5 without interfering with af, iris, whatever?

curious....
Former user wrote on 5/21/2012, 7:34 AM
Bob,

Thanks for the information. It has been a while since I messed with filters in photography so I wanted to make sure I would get the right thing.

Dave T2
Former user wrote on 5/21/2012, 7:44 AM
Bob,

another quick question. I have a good CPL from my still camera that is a 52mm. If I buy a 43mm to 52mm adapter, I don't lose anything do I? (my lens on the Vixia is 43mm).

I am assuming there is no problem when only using the center area of the polarizer.

Thanks
Dave T2
paul_w wrote on 5/21/2012, 8:14 AM
I have also heard that the whole linear/circular auto focus thing is a myth.
Video cameras auto focus fine with both - so i was told.
Personally, i had bought CPLs before i knew about this. So never had the problem.
What do others think? Any evidence to prove otherwise?

Paul.
Opampman wrote on 5/21/2012, 9:14 AM
I have used a linear filter for years and never had a problem with it. I'll admit I rarely use autofocus but when I have, it worked fine.

Kent
Former user wrote on 5/21/2012, 11:17 AM
I dont' know about the newer AF technology, but in the earlier days of still camera autofocus, the CPL was definitely a requirement.

I think it was based on the infrared light they used to autofocus, but I am probably wrong.

Dave T2
farss wrote on 5/22/2012, 6:45 PM
"i usually use a cpl in my matte box for shooting horses, would i see any difference if i used a linear"

Visually there should be no difference, the whole "auto" thing I haven't a clue.
To my mind apart from a being a bit more expesnive there's no reason not to use a CPL so I would suggest playing safe. It's a bit like always using balanced audio :)

Bob.
farss wrote on 5/22/2012, 6:49 PM
"another quick question. I have a good CPL from my still camera that is a 52mm. If I buy a 43mm to 52mm adapter, I don't lose anything do I? (my lens on the Vixia is 43mm).

None what so ever. This is what happens when you use a matte box after all. So long as the filter is big enough to avoid vignetting all is good.

Noteable exceptions are thing like Grad NDs and diffusion filters. With both of them aperature and focal length makes a difference to how much impact the filter has on the image.

Bob.