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Old 08-02-2019, 09:16 PM
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Camelopardalis (Dunk)
Drifting from the pole

Camelopardalis is offline
 
Join Date: Feb 2013
Location: Brisbane
Posts: 5,425
If you’re putting a powermate in-line, then you’re effectively increasing the focal length of the scope, and thus increasing the radius of curvature of the scope, resulting in less severe field curvature than before.

Just remember that any field curvature is going to be at maximum on the field edge, not near the centre.

Field flatteners are important for imaging where the camera sensor is flat, whereas the focal plane (especially so in small refractors) is curved. Without correction, the stars would be out of focus towards the edges/corners.

The eye generally accommodates field curvature, but eyepiece design can influence how it appears, and some eyepieces are more suitable to some types of scope than others.
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