Just a question in regards to polarizers...
Can someone explain to me the difference between a circular and linear
polarizer? Could I use a linear polarizer on my Oly which has internal AF
ie. the lens doesn't rotate?
A circular polarizer is in principle a linear polarizer with a depolarizer on the back, first filtering out light with a certain polarization and then depolarizing the light coming through the filter. It works on all cameras, but is a bit more expensive.
Most modern cameras, and I think all AF cameras, have beam splitters in their AF-system (as well as their light meters). These beam splitters are polarization dependent. Therefore, to get correct metering and AF the light coming into the camera should not be polarized.
Try placing a linear polarizer in front of another and rotate them relative to each other, and you see what you AF sensors or light meters will see if you put a linear polarizer on a modern camera. You can get anything from almost all the light through the second filter to absolute darkness, if the polarizers are good.
DagT
