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Message: <blockquote data-quote="henry link" data-source="post: 1431359" data-attributes="member: 6806">Clay,I used a USAF 1951 Resolution Test Pattern to measure the resolution of two Kowa 883s. I have a 10m indoor and several longer outdoor test set-ups for that purpose. If you want more details I'll be happy to supply them. The better of the two Kowa 883s I tested measured 1.35 arcsec. On the USAF chart, a perfect 88mm scope would have resolution of about 1.32 arcsec (116/D), a perfect 80mm scope would be 1.45 arcsec and 82mm about 1.41. In my tests the theoretical resolution limit is reached by well corrected astronomical APOs, but I rarely see birding scopes do better than 130/D.BTW, any chance of Swarovski supplying an adapter to use the spotting scope eyepieces on astronomical scopes? I've had great success with the 20-60X zoom and the excellent 30XW on astronomical refractors using home made adapters. Henry</blockquote>