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A simple focal reducer wouldn't, however, the Celestron/Meade R/C is not a simple reducer, it has additional lens elements designed to flatten the field of SCTs.


Mike

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I have tried using the Meade Variable focal reducer with my Intes 703 (a Mak-Cass) with unacceptable results for imaging.

With the reducer installed, I get vignetting, which in and of itself is correctable with Flats, I suppose.

What is intolerable, however, is elongated stars all around the edges, with the degree of elongation becoming greater the further from the center of the image. The direction of star elongation radiates from the center of the image, following the same orientation as would imaginary rays of light coming from a central point in the image.'

I also noticed that outside of focus, stars at the edges of the image are not completely donut-shaped, but rather crescent-shaped, the missing half of the donut being towards the outside of the image, away from center.

Is this coma? Is it due to the fact that the Meade focal reducer is also a field flattener, intended to flatten the field of a parabolic mirror, and in so doing, distorts the field of my spherical-optics Mak?

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Clear Skies,
Sal Giambruno
Intes M703D 7" f10 Maksutov-Cassegrain / Takahashi NJP Temma II / OPTEC TCF-S Focuser / SBIG ST-2000XM / CFW-9 / Astrodon LRGB Filters

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