Linear vs Circular

I read that a The only difference between a linear and circular polarizer is that the circular polarizer has a thin layer that reverses some of the polarizing effect so that the auto focus mechanism in the camera works correctly. I don't get it. What is the difference between reversing a fraction of the effect with a second layer and simply manufacturing the primary layer a little weaker. In other words, if the circular polarizer is too strong why not make the polarizer weaker rather than "reverse" or undo the effect with more glass?

Secondly, if this reversing layer reduces a portion of the light rays, then why does it have the same filter factor as the linear polarizer filter, which is 1.3 stops.

Thirdly, if I plan to use a polaring filter only with my manual focus 24mm TSE lens, then is there any advantage, other than price, of using a circular polarizer instead of the linear one?

texshooter wrote in post #16973923
I read that a The only difference between a linear and circular polarizer is that the circular polarizer has a thin layer that reverses some of the polarizing effect so that the auto focus mechanism in the camera works correctly.

The second plate doesn't "reverse" the polarizing effect: it converts it to a circular polarized light. Apart from allowing AF, a circular polarizer is also more appropriate with DSLRs that have anti-alias filters. A linear polarized light can cancel out the anti-aliasing.

http://en.wikipedia.or​g …rizer#Circular_​polarizers

Heya,

If you're shooting manual focus, the linear is often the choice.

Very best,

texshooter wrote in post #16973923
Thirdly, if I plan to use a polaring filter only with my manual focus 24mm TSE lens, then is there any advantage, other than price, of using a circular polarizer instead of the linear one?

You are correct in this respect, but if you have some autofocus lenses as well then you need a circular anyway which will work on a manual focus lens. I do have to admit, you can find some linear polarizers out there in camera shops junk boxes for next to nothing in cost.

I also suggest you review the article at http://www.bobatkins.c​om …technical/polar​izers.html for a good explanation of both types of polarizers.

texshooter wrote in post #16973923
Thirdly, if I plan to use a polaring filter only with my manual focus 24mm TSE lens, then is there any advantage, other than price, of using a circular polarizer instead of the linear one?

There seems to be a wider selection of higher quality circular polarizers due to higher demand for them. But theoretically, no.

A technic called Cross polarization, the use of linear polarized film over your source of lighting and a CPL over on he lens.

What is the subject that you are photographing ?


Farmer