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Message: <blockquote data-quote="Kevin Purcell" data-source="post: 1527203" data-attributes="member: 68323">Try looking at some polarized sky with phase corrected roof bins.The roof prisms rotate the direction of polarized light if the roof edge is not in the same plane as the polarizer of the sunglasses (i.e. horizontal).Try it out. Wear a pair of polarized sunglasses. Hold another pair at right angles (so they appear dark) whilst viewing a uniform scene (the latter helps be is not required). Then insert a pair of roof prism bins in between the polarizers with the objectives facing towards you. Rotate them and you'll find the image is blackest when the roof edge is horizontal.The prisms in the two barrels are rotated at different angles so they don't line up with the vertical or the horizontal or each other. By design.So when you view a polarized light illuminated scene you get interesting differences in sky brightness in each eye which looks "Like, psychedelic, Man". You get an odd faux 3D effect.Generally shows up when looking at birds in the tree tops.You don't get this effect in porros (even though the output light is polarized a bit).This ultimately is a good argument for wanting to put linear polarizers in front of the objectives of a roof prism bin (before any of that annoying rotation!).BTW, the above was checked out with a Zeiss Victory and a Nikon SE. None of that cheap junk (though it gives the same results).</blockquote>