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Message: <blockquote data-quote="henry link" data-source="post: 1497194" data-attributes="member: 6806">Frank,You don't need to compare it to another scope. Just measure the resolving power with the USAF chart and do an artificial star test. Those tests will show how close it comes to diffraction limited resolution, what aberrations are present and how severe they are. That's really almost all you need to know about the axial image quality.But, if you want to compare it another 50mm scope, make a 50mm stopdown mask for your Pentax 65mm. The fieldstop tends to blur in nearly all zoom eyepieces as the focal length of the eyepiece changes over the zoom range.HenryBTW, this scope actually had the lowest score for "image quality" in the Porters' inscrutable scoring system, even though its "resolution score @ 30x" was slightly better than the (probably defective) last place Minox. The Yukon's overall score was buoyed by what was judged to be a "superb" focus knob.</blockquote>