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Message: <blockquote data-quote="Kevin Purcell" data-source="post: 1743555" data-attributes="member: 68323">Comments on your numbered points: 1. The sense of rotation of the device doesn't make any difference ... relative rotation to a polarized light source with the bins adding a rotation of the polarization themselves. Rather like birefringent minerals under a microscope with polarizers. It's physically easier to do it this way with two fixed polarizers so I think more people might try it this way.Another way to check this is for me to rotate my head at 90 degrees so the sunglasses polarizers (now horizontal) are crossed with the LCD polarizers (vertical) so no light is seen when viewing the screen directly. Then introduce the binoculars under test and rotate them. You can see the light from the screen through the binoculars as they're rotating the polarization of the light. The colors and intensity changes are the same on quick inspection.2. Linear polarizers are easier to find and are a rather better defined physical setup.4. The brown tint is really bumping the transmission in the red/orange and reducing it in the blue. But I could still see the blue. I have another set of "grey" glasses that are actually biases in the other direction (with greay blue bias).I suspect my results are a it more easily reproduced (you just need a pair of linearly polarized sunglasses and an LCD screen) as I just used linear polarizers.With a linear polarizer filter and a digital camera you could photograph the effect and perhaps even make quantitate measurements.As I mentioned, but didn't make clear, in the results there is an "absolute" difference between PC and non-PC bins in (at least) my version of the test. And I think in yours as you mentioned the same effect.The non-PC bins show no color at any rotation and they drop to zero transmission (black) at some rotation on a one side of the roof then on the other side of the roof at a different rotation. All the PC bins showed some change in color with rotation and didn't drop to zero transmission (though some come close) but when they did drop to their lowest transmission it was very close to equal on both sides of the roof at a particular rotation (not quite ... either side of that point you can it it's perhaps a little darker on one side than the other ... but the color changes too). That's the critical difference: what is the minimum transmission and how does it vary between the the two roof faces with rotation angle.All the other variation was between the different PC coatings which affected the amplitude of the transmission change and the color.Checking a couple of other bins:Zeiss Victory 8x20 very similar to the other Zeiss bins tried above. Weak color effects and high minimum transmission.Zeiss Conquest 8x30 very similar to the other Zeiss bins tried above. Weak color effects and high minimum transmission.I guess Zeiss have their PC coating as good as they wish to make it and feel little need to change it. Meopta Meostar 8x32: a little more color and transmission change than the Zeiss but less than the Pentax or Chinese ED bins. Quite close to the Zeiss.Bushnell Discoverer 7x42: Slightly more transmission variation and more color than the Meopta (but less than the Chinese EDs).Bushnell Elite 8x43: Very similar to the Bushnell Discoverer but perhaps a little more intensity variation.Bushnell Legend 8x42 (old one not the HD): Has clearly more intensity variation and more color than the Elite or Discoverer and the Chinese ED bins.Pentax WS 8x25: similar to the other Pentax. Not as dark as the SP but not as light as the WP. It gets quite dark (and quite blue) at 45 degrees (when both sides of the roof are the same intensityThe other thing I notice is the intensity varies with on-axis off axis position so it's better to view the bins at a distance from the eye rather than close up (and try to stay on axis).I have no idea how much these tests show an actually effect of the PC coating design when viewing through the bin except in those cases where the user is wearing sunglasses and viewing a target that is lit with polarized light (the sky does generate a lot of polarized light and bees use the variation of it for navigation) or is strongly polarizing light in reflection. That of course gives "weird" color and intensity shifts that vary with the side of the roof prism. It would seem that Zeiss in the case would minimize that effect. Does it impact in any other way? I don't know.</blockquote>

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