I don't need a circular pol. filter... right?

Nytmair said:
I just wanted to double check and make sure this is the right filter (the price seemed low so I wanted to see if it would be ok.

For my camera (panasonic fz20) I am going to get an adaptor that allows me to use 62mm filters/lenses. Now, becuase it's not an SLR camera, the lens does not rotate to focus, it's all within the camera. I will be able to use a cheaper/linear polarizing filter becuase of this, correct?

Circular polarizers are exactly the same as linear polarizers (they are orientation sensitive), except that they contain an extra element (some kind of "wave retarder", I'm not too strong in optical physics so I'll leave it at that) that makes circularly polarized light come out the rear end after the linear polarizer does its job. The reason people use them is because sometimes linear polarizers **** with either the autofocus system or the light metering system (can't remember which, or maybe it's both) due to the construction some manufacturers use - which involves linear polarizing elements. I have a very new canon EOS body (elan 7n) and I bought a linear polarizer for it not realizing it could cause interference. Fortunately, it doesn't. Everything works exactly fine, autofocus and metering are both perfect.

In both cases, rotation of the front of the lens means you have to readjust your polarizer.
 
ksmattfish said:
Name one auto focus camera that will work (focus correctly) with a linear polarizer.

My canon Elan 7n focuses perfectly with my linear polarizer, unless it's actually a circular polarizer and I don't realize it. Bought it used, HOYA PL 58(phi) is written on the edge.
 
NakedAnt said:
What if I always use manual focus? Are there other reasons one shouldn't use a linear polaizer on an AF SLR?

I think the link that Feny gave us tells it pretty well... ANd those reasons shoul dalso be enough to avoid a linear filter for an AF camera. :wink:
 
ksmattfish said:
Jamie R said:
It's a bit more complicated than that Matt.

If a camera uses a sophisticated metering system, including 'splitting off beams of light' to measure differential exposure, then a circular polariser is required. Otherwise the polarised split beam going to a 5% portion of the exposure meter becomes drastically confounded.

The theory boggles me. Wish someone could explain it to me too....

Name one manual focus camera that won't work with a linear polarizer.

Name one auto focus camera that will work (focus correctly) with a linear polarizer.
Canon S1 IS...
As well as every other camera which uses the CCD to focus.
 

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