Hi, As I had no experience with photographic polarisation filters so far, but did have practical experience with polarises from my degree in physics, I was wondering about the following: I bought the Hoya Pro 1 Circ. Pol. for use on a 70-200 f/2.8 L IS. It surprised me to see that in fact it can be turned - and that the effect depends on the angle. One would expect a polariser to let light pass that is oriented in the way described in it's name. So one would expect a circular polariser to let circular polarised light pass. As circular polarised light is independent of the orientation of the polariser, there should be no noticeable difference when the polariser is turned.
My assumption is the following: As in photography we talk about filters, the circular polariser is in fact a circular polarisation filter - filtering out circular polarised light rather than letting it pass. Therefor a photographic circular polarisation filter would physically be a linear polariser. Anything else wouldn't make sense - physically speaking that is ;-) So is this correct? And does this mean the AF sensors work fine with linear polarised light in any direction? I'd expect this to be the case for circular polarised light... Regarding the Hoya Pro 1 Circ Pol.: How are your experiences with wider angle zooms (24/28-70 f/2.8 L and 16-35 f/2.8 L)? Is there any vignetting, glare etc? Cheers, Stefan -------------------------------------------------------------------------------- * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
