almost all optics are clear to a certain degree. grinding glass and polishing it isnt very hard actually, ive seen it beeing done at one of nikon canadian grindhouse's. the biggest difference in these cheap knock offs and real scopes are in the colour correcting glass (if any), optics coatings and culmination of the elements. if a scope is lacking in any of these areas the scope will experiance the same problems galileo had with his telescopes. fringing, halos, blackouts, colour distortion and every bad thing you can think of will effect a bad scope at long range with high magnification which make the scope useless at long range irreguardless of the features it make have knocked off from schidt bender