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John - 60mm in fast scopes ? Oh really !? The 32mm maybe but the 60mm is only suitable for f/10 or longer focal ratios - and that means SCT, mak or refractors; not newtonians.
If they had any sense they'd have designed to match the field curvature of such scopes which is opposite to that of newtonians.
Even in small refractors there is a question as to how wide the well corrected field is; outside that images will deteriorate extremely sharply.
Hence I'm not surprised at all to hear someone say half the field was not in focus.
And FWIW I have a no-name cheap $59 38mm 70 degree eyepiece that is a perfect match for my 130mm refractor, razor sharp to the edge. As far as I'm concerned anyone buying a masayuma is shelling out stupid money for a badge.
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