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Message: <blockquote data-quote="ronh" data-source="post: 1743766" data-attributes="member: 55514">I know only too well from using telescopes between f/4.5 and f/12 how much better any eyepiece works at higher focal ratio. Not even the most large and complex Nagler eyepiece will give a sharp edge at f/3.5, and neither can a small and lightweight binocular eyepiece.Abbe-Koenig prisms clearly have a much shorter path length than Schmidt-Pechans. With these two simple facts, I think I can see clearly the progression in size of the sharply focused "sweet spot" in the three "alpha" brands.At the bottom, with the smallest sweet spot, is the (>32mm) Zeiss FL, which has traded this quality for the added brilliance and perhaps the lighter weight of the AKs.Next up, the Leica with its SPs, which even though more compact than the Zeiss, has a longer focal length, and a larger sweet spot.At the top is the Swaro EL, also with SPs, but fully as long as the Zeiss, with the greatest focal length, and the widest sweet spot. The Swarovision is said to be a little better at the edge than the original. Certainly it could only get a little better, which was almost unnecessarily good already. Some of the improvement may result from a compromise related to the new lowered geometrical distortion.This just makes too much sense. Am I oversimplifying?Ron</blockquote>