Only the Canon drop in CPL can be adjusted (there's gearing to a knob on the outside). If you get a 52mm CPL and the drop in holder, you must remove the filter to adjust the polarization angle. So for a CPL, get the Canon one.
For ND filters with the screw in holder, I don't know how thick is too thick (haven't had a need for one yet), but I'd probably get Slim or XS-Pro just in case.
+ 1 for my Teacher, Mr. Neuroanatomist.
Yes, High cost of Canon 52 mm. Drop-in CPL Filter---And Very difficult to buy one----Not many of them in the market, BUT, IT worth for me to improve the quality/ contrast of my photos from my EF 600 mm. and in side my Lens all the time---Yes, please remove the plastic( ? or Glass) / clear filter that come with the canon lens.
"" By Gerald Reed "Jerry" (Essex, CT) - See all my reviews
This review is from: Canon 52mm Drop-in Screw Filter Holder 52 (accepts standard 52mm filters) (Electronics)
I own and use frequently two of Canon's best lenses, the Canon's 500 mm f4 IS and 300 mm f2.8 IS. Each of these lenses has an option that I did not originally purchase. I was shooting at the Rookery in Venice Florida, one of the nation's outstanding sites for photographing wading birds in their nests, when Tom Mangelson (Google his name) walked up and asked me how it was going. He asked, "...are you using Canon's drop in polarizing filter?" From my dumb-struck expression it was obvious to the Master of Wild life photography that I was someone in need of help. He said, "You should consider getting one. It will take you images to the next level." After Tom walked off, five of the photographers walked up to me and said, "Do you know who that was?" I showed them the card he had given me. "Tom Mangelson, no s**t!"
I bought one for both lenses. Tom was right. Thanks Tom. "
Ha, Ha, Ha---After I read this Article--I order one.