Polarizer question- help

I've got a Canon variety Sigma 120-300 2.8 OS. I"m thinking about putting a polarizing filter on the lens. The hood is really deep and that would make a circular polarizer a major PITA to adjust. Would a linear polarizer be an option. I've got to make sure that before investing money in a 105mm filter it would be worthwhile. Any ideas/comments would be welcomed. Thanks in advance.
t

Remove the hood.

acajun wrote in post #15733010
I've got a Canon variety Sigma 120-300 2.8 OS. I"m thinking about putting a polarizing filter on the lens. The hood is really deep and that would make a circular polarizer a major PITA to adjust. Would a linear polarizer be an option. I've got to make sure that before investing money in a 105mm filter it would be worthwhile. Any ideas/comments would be welcomed. Thanks in advance.
t

Both "circular" and "linear" polarizing filters are physically round and they operate the very same way. You need the "circular" type to make sure that autofocus works properly. A "linear" polarizer could cause problems with your camera's functions.

I don't know about how the hood attaches to your Sigma lens, but with my Canon lenses (which all use bayonet-mount hoods) I can pull the hood off if needed to adjust the polarizing filter's position and I can reinstall the hood without upsetting the filter's position.

acajun wrote in post #15733010
I've got a Canon variety Sigma 120-300 2.8 OS. I"m thinking about putting a polarizing filter on the lens. The hood is really deep and that would make a circular polarizer a major PITA to adjust. Would a linear polarizer be an option. I've got to make sure that before investing money in a 105mm filter it would be worthwhile. Any ideas/comments would be welcomed. Thanks in advance.
t

A linear polarizer or circular polarizer doesn't mean it's square or round, it's a different kind of polarizing material. There are round linear polarizers as well as square circular polarizers (although rare).

Linear polarizers mess with your metering so I'd avoid those completely unless you need it for a very specific purpose such as building a variable ND filter or cross polarization (although even then you only need an LPL on your lights).

Edit: dammit, skip beat me to it

TweakMDS wrote in post #15733192
A linear polarizer or circular polarizer doesn't mean it's square or round, it's a different kind of polarizing material. There are round linear polarizers as well as square circular polarizers (although rare).

Linear polarizers mess with your metering so I'd avoid those completely unless you need it for a very specific purpose such as building a variable ND filter or cross polarization (although even then you only need an LPL on your lights).

Edit: dammit, skip beat me to it

Thanks for the info on the difference, but I didn't say anything about "square filters". I

SkipD wrote in post #15733183
Both "circular" and "linear" polarizing filters are physically round and they operate the very same way. You need the "circular" type to make sure that autofocus works properly. A "linear" polarizer could cause problems with your camera's functions.

I don't know about how the hood attaches to your Sigma lens, but with my Canon lenses (which all use bayonet-mount hoods) I can pull the hood off if needed to adjust the polarizing filter's position and I can reinstall the hood without upsetting the filter's position.

Thanks Skip. I was just trying to save a step.

What size filter does that lens take?

Tapeman wrote in post #15735305
What size filter does that lens take?

It takes a 105mm filter