Quote:
Originally Posted by Astro_Bot
@ anyone: Would it be fair to characterise the Hioptic ED127 as a semi-APO?
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Yes it's a semi-apo, for two reasons:
Chromatic aberration: blue is slightly out of focus from the other wavelengths and;
Spherochromatism: while the scope may have a high strehl in one colour (.95 or better) spherical aberration brings the performance down at other wavelengths.
It's still a decent scope providing you get a good sample, but if you pay a multiple of it's price you can get a full apochromat with high strehl across the visual wavelengths and further.