I’m downsizing from my old camera1 to an E-P1, so I’ve had to hunt down a new CPL. Problem is the kit lens is 40.5mm, which must be unusual as everywhere I asked had no filters to speak of in that size.2 Looking on eBay, I noticed absolutely no brand names that I recognised, so I took the punt on a dirt cheap CPL, and what arrived was instead a brand new type of lens, the SGCD, for my hard earned $10. Here’s the before and after:
When you see advertising for CPL filters there’s the stereotypical before+after of sky or Koi in a pond; I was all outta’ Koi. The before photo is on the left, and the second photo has the CPL filter attached. No, I didn’t get these around the wrong way, the CPL filter I bought is actually just smoked glass. The end result drains the natural colour from the photo and darkens shadows into obscurity, resulting in some awfully muted skies.
The guilty party; a Made In USA3 quality Fotodiox, that famous optical company everybody has been telling you about. Nothing is outwardly wrong with the case or the filter, the screw thread is perfect and the case looks more modern than most other brnads, but as the photos show it’s a worthless piece of glass. There’s nobody I hate enough to give this to, so I guess I’ll hold onto it in the case that it finds a use. Needless to say, a $40 Hoya CPL is on it’s way, my lesson fully learned. 
For the m4/3 readers: you can actually use a regular linear PL as there’s no phase detection AF to cause trouble, but for the cost of finding a multi-coated PL, it’s cheaper and easier to source a good quality circular.
