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Message: <blockquote data-quote="henry link" data-source="post: 1289548" data-attributes="member: 6806">Ron,Great job with the measurements and especially photographing the star test. Are you using a real green filter or is the green color a computer generated virtual filter?My usual indoor artifical star test is at 10m. I tested a few binoculars at 5m just now and I did see worse undercorrection than at 10m. Outdoors I star test at about 33m and usually see improvement at that distance compared to 10m. You're analyzing the spherical aberration to a level of detail that I've never tried to do with binoculars, so I don't think you can learn anything from me. Mostly I star test binoculars to detect defects like astigmatism, miscollimation, pinching or a bad roof prism edge. Your Promaster doesn't show any of those defects (well, maybe slight pinching), but plenty of expensive binoculars do. Considering that your star test was done at 5m I would say it's just fine and combined with the excellent resolution measurements I wouldn't expect to see any problems in the axial sharpness of this binocular. The measurements and star test could be considerably worse and the binocular could still be perfectly sharp  in the center at 8x.I am a little surprised by the light transmission measurements. Promaster claims only 99.3% transmission for each surface which isn't all that impressive for modern multicoating. Combine that with the silver mirror coating and I would expect something closer to the Trinovid transmission curve. Perhaps the 99.3% was just pulled out of a hat by a marketing writer who thought it sounded good.Henry</blockquote>

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