Today’s Question: I’ve read that circular polarizing filters were designed specifically for cameras with a mirror, such as a DSLR. But for cameras without a mirror, a linear polarizing filter is the better choice. Should I be using linear polarizing filters on my mirrorless camera?
Tim’s Quick Answer: You can use a circular polarizer for either type of camera, but you should avoid linear polarizers for digital SLR cameras due to the mirror.
More Detail: The real issue here is that a linear polarizing filter should not be used with a single-lens reflex (SLR) camera. The reason for this is that the beam splitting of the mirror on an SLR camera interferes with the phase-detection autofocus and metering. For this reason, only circular polarizing filters should be used with SLR cameras.
For mirrorless cameras you can use either circular or linear polarizing filters, because there isn’t a mirror for the linear polarizer to interfere with. However, to me the safest approach is to always choose a circular polarizing filter rather than a linear polarizing filter. In addition, circular polarizers are much more common, so they’ll be easier to find in general.
