DSLRUsers.com

Posted: **Thu Jan 27, 2005 9:02 pm**

Hi all,

I recently inherited some filters from my boss, including a polariser. I took a few shots with the polariser, and it seemed to be working alright. I then read that linear polarisers are not compatible with modern autofocus systems and followed the instructions about holding the filter up to a mirror and flipping it over to determine that the one I was using was linear.

So my question is, does anyone know anything about the difference between linear and circular polarisers, 'cos this linear one seems to work fine??

Jon

Posted: **Thu Jan 27, 2005 9:34 pm**

Taken from here: http://www.luminous-landscape.com/tutorials/polarizers.shtml

Circular Vs. Linear Polarizers

There are two types of polarizing filters available — linear or circular. Linear polarizers are more effective and less expensive than circular ones. But circular polarizers are needed with just about any camera that has a through-the-lens metering system, or autofocus.

The reason for this is that both of these systems use semi-silvered mirrors to siphon off some of the light coming though the lens. If that light is linearly polarized it renders either the metering or the autofocus ineffective. This means that you're going to have to buy circular polarizers unless you're shooting with a pre-1970's camera, or a view camera.

Posted: **Thu Jan 27, 2005 9:41 pm**

Thanks for the link. Looks like i'll not be using that polariser again then... Still, got a red and blue filter to play with too

DSLRUsers.com

Linear vs Circular polariser

Linear vs Circular polariser