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Message: <blockquote data-quote="Binastro" data-source="post: 3368183" data-attributes="member: 111403">Henry, do uncoated Porro prisms have 4 surfaces, each losing 4% or slightly over?My hands are not great, so I just use overhead bulb without magnifier.The reflections in eyepiece are confusing, maybe from aspherical surface.I suspect one single coated surface and 2 obvious green MC.Maybe secondary spectrum is included in lab transmision figures.I also think less than 70%.I do look at crows at 2a.m., but they sit in our oak tree. A married couple I think.I've also seen them sharing with an owl.Correction. It was the 2 pigeons sharing with the owl.Either pigeons or crows use the oak tree at night, but not at the same time.Fog supposedly 100metres, but here more like 200metres. Sun quickly burnt it off.2 small sunspots today.</blockquote>