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13mm Stratus
Have had a 13mm Stratus eyepiece for about two weeks now and have been observing with it every night since, my log book now has a number of new entries after a lull of a considerable length of time.
On axis --no complaints: sharp, good contrast and transmission.
Off axis--astigmatism rising sharply to the edge from about 10% from the edge. Also noticeable field curvature. The usable field is about 75%to 80%.
I was wondering if this is normal for this eyepiece in a 10" f5 scope, does anyone else have the same experience? I was under the impression that the edge-of-field performance would be better than this (though not perfect). Your comments would be much appreciated.
Cheers
Malcolm
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