wide angle lens and CPL filter question

I have an SX40 HS and use the 67mm filter adapter. I want to get a (67mm) wide angle lens for it and already have a good 67mm CPL I like a lot.

I would like to attach the wide angle lens to the CPL at the 67mm connection ... the front of most of the wide angle filters are 82mm.

My question is will the 67mm CPL still be effective with the wide angle lens in front of it or should I be looking for an 82mm CPL to attach to the front of the wide angle lens? Does it matter?

It doesn't really matter where the filter is in the optical path as far as polarization goes. The filter's thickness may cause a slight deviation in the wide adjustment factor, but you will still be seeing what you get. My suggestion - get the lens adapter, try it with and without the 67 mm polarizer in place then if you don't like the results with the polarizer worry about getting a larger, front-mountable polarizer. Since you want to use it on an SX40, unless you intend to venture into DSLR territory you don't really need to get a CPL, a linear polarizer will do fine.

Jon wrote in post #16375080
... unless you intend to venture into DSLR territory you don't really need to get a CPL, a linear polarizer will do fine.

Thanks for the answer. I thought the problem with a linear polarizer on any digital camera was that it interfered with the autofocus system.

It can interfere with the AF on a DSLR (or film SLR) only because they rely on a partially-reflective mirror to deflect part of the light from the lens to the secondary (AF) sensor and partially-reflective mirrors are themselves polarizers. An SX40 (or other non-reflex cameras) uses the same sensor for AF and image capture. Historical note - the old Canon FT, FTb, F-1, EF and their fully-mechanical-shutter Canon contemporaries also required a CPL, since they used a partially reflective mirror to deflect part of the light to the metering sensor. Most other SLRs of that era metered directly off the focusing screen.

Thanks so much ... very useful.