Quote:
Originally Posted by refractordude
Hello There
It has arrived. Will let you all know how it does with a F5 80mm achromatic. Hoping for sharpness very close to the edge.
Clear Skies
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The ultraflat eyepieces have a flat focal plane, they were designed specifically to be used with flat-field scopes used for imaging, such as the quad or quintuplet APOs - not achromats.
Your 80mm achromat has a curved focal plane, like a soup-bowl, so with this eyepiece, if its in focus at the centre, it wont be at the edge, and vice versa.
An Erfle or SWA eyepiece is a better match for a small achromat like yours, as they have curved focal planes approximating that of an achromat.