Polarizing Filters

[Roger Williams]

I'm planning to buy a 67mm polarizing filter for use on my 17-50mm f/2.8 wide angle (28-80mm on the 40D) and Canon 70-200mm f/4 IS lenses. Is it necessary to buy a "slim" filter for the wide angle lens or will the regular filter suffice? Is there a major quality difference between B + W, Hoya, or other brands?

Thanks for your advice -

roger

[Harold Davis]

cant answer about the need of the slim, but all the research i did showed a slight edge in quality to the hoyas for the circular polarizars.

[Roger Clark]

You might look at your lens set and find out how many filter sizes you have. For example, if one of your lenses is 72 mm, then it could save money if you bought a step-up rings for the lenses with smaller filters rather than buying different size filters for each lens. I use 72 mm filters and lens caps on all my smaller lenses, for example. Although with a step-up ring on the 70-200 f/4, the lens hood will not longer fit. On the wide-angle lenses, using a larger filter via a step-up ring also ensures you won't block the corners of the frame. This strategy also standardizes lens caps.

Here is a web page about evaluating polarizing filters:
http://www.clarkvision.com/photoinfo...rizing_filters

Roger

[Maurice Allen]

Cokin P filter holder would work also. Then you could use the Singh-Ray LB Polarizer.

[Roger Williams]

Thanks for the ideas. Singh-Ray makes nice filters but the LB Polarizer is a combination polarizer and warming filter. I don't particularly want to warm with a polarizing filter - I can do that with white balance or PS.

What I'm trying to determine is the cutoff point in wide angle lenses where a "slim" filter gives better edge results than polarizing filters of normal thickness. As mentioned above, the lens in question is a 17-50mm which is 28mm on the wide end with a Canon 40D. I'm hoping the regular polarizer with front threads will work ok.

roger

[Roger Clark]

Roger,
If the 17-50 is a 35 mm lens (not and EF-S lens) then the angles on a 1.6x crop sensor should be no problem with either filter. If you plan on an upgrade to a full frame sensor, then it's another story.
Roger

[Roger Williams]

mclark, are you saying there will be a problem with an EF-S lens? The lens in question is a Tamron XR Di2 lens which is designed exclusively for use on APS-C sized sensors. I decided to save a hundred or so bucks and buy the Tamron rather than the EF-S 17-55mm f/2.8 Canon. Its a wonderful little f/2.8 lens for the money and I can put the balance on a polarizer!

roger

[Roger Williams]

Spoke with Tamron technicial folks, which didn't cross my feeble mind until after the last post. A polarizing filter of regular thickness will work fine on this lens and the 40D with its APS-C sized sensor. Different story with 17mm lenses on full-frame cameras.

Thanks again for your advice. Perhaps the discussion will also be useful to others.