| Re: What's going on with Cir. Polarizer?
Ok, brain was frozen.
The quarter wave plate(ie. circular polarizer) is effectively de-polarizing the light, that is it is no longer linearly polarized. So it is put behind the linear polarization portion of the filter.
So if you turn the filter around in the wrong direction the polarized light from the LCD is de-polarized. The polarization provided by the rest of the filter will not interact with the polarization of the light from the LCD.
So to recap:
A linear polarizer accomplishes the select contrast enhancements and filtering that we typically want. If we then pass the resulting light thru a circular polarizer it will be no longer be linearly polarized. This will eliminate any unwanted interactions with the rest of the optics in the camera.
| 
Linear Mode
