I have a Canon 18-55mm lens. I want to buy a new polarizer for it. The diameter of my lens is 58mm. I want to go for Hoya. But there are 5 or 6 different circular polarizers of Hoya for 58mm diameter. I'm confused about which one should I go for. Can someone explain the different types to me so I can decide?
The ones with the HD designation are better because they transmit considerably more light than any other circular polarizer. This is the minimum you should consider for high quality performance with excellent color-balance, low flare and even illumination.
They also have an HD2 line which has the same optical performance but is made of temperred glass which makes it stronger and much more resistant to impact. Wether you need this depends if you usually drop your filters or bang them against something.
They just announced the HD3 which is apparently even harder and officially delivers the same optic performance as the rest of the HD line. This is one I did not try but I can vouch for the HD and HD2 ones which are the very best polarizers I own. I still have a non-HD one too and there is 1 1/3 stop difference between them, which is much less usable and compares to what you get in transmission with other brands.