Home » Identifying a Minolta filter. It is a polarizing filter but it is not marked as a "Circular"

How to test if it's

On February 6th, 2008 astropaul says:

How to test if it's Circular.....

A "Circular" Polariser actually consists of a polariser in front and a depolariser behind it. Now it's convenient that LCD displays work by polarisation too, or if you have polarised sunglasses they can be used for the test too. The method is to look at the LCD through the polariser then turn the polariser the "wrong" way around and look again. At least one way around it should be possible to make the display darken completely (or the view through polarised sunglasses). If the display darkens with the filter facing both directions, it is not "Circular", if darkening is only observed in one diection, the filter is "Circular".

HTH

Paul.

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