[photoptimist]

This depends upon the degree of polarization, but 1/8th to 1/2 stop difference can be observed.

Sounds plausible. If one is hyper-concerned about the exact exposure in order to park the highlights just below the clipping point of the sensor or are doing high-key work, then a circular polarizer would be a good idea. But if one has some latitude, 1/8-1/2 stop error is not going to make a big difference in the final image.

The effect on the OVF did make me wonder if a circular polarizer would make it easier to see and control subtle polarization effects on sky, leaves, water, etc. and not be fooled by the simple dimming and brightening of the OVF image due to interactions between the polarizer and main mirror.


P.S. The test also revealed that my Quantaray CP was a piece of crap! When crossed with a another high-quality polarizer, the Quantaray passed a lot of blue light!

[lithedreamer]

The effect on the OVF did make me wonder if a circular polarizer would make it easier to see and control subtle polarization effects on sky, leaves, water, etc. and not be fooled by the simple dimming and brightening of the OVF image due to interactions between the polarizer and main mirror.

This makes me feel better about having spent the money on a CP. I tend to choose objects like reflections in windows, where this might actually matter.

[photoptimist]

This makes me feel better about having spent the money on a CP. I tend to choose objects like reflections in windows, where this might actually matter.

Indeed!

After these tests, I'm considering upgrading to CP myself to help ensure that I don't get fooled by the effects of linear polarization on the OVF's image.

P.S. You might like this trick: to about double the strength of a reflection in the window or water: turn the polarizer until the reflection disappears, then turn it exactly 90°.