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The Wizard Nebula in H-alpha
This is part of the testing I'm doing on a 25 year old AP Starfire 142 that I recently acquired. This is at f/7 with no flattener. I'll be adding O3 data soon.
5 x 15min
QSI 583ws, Mach1 mount

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Comment by Greg Marshall on July 7, 2012 at 8:48am

Marc, a curved field produces elongation of stars away from the center (along the radial), so over-correction causes elongation in a direction perpendicular to the radial. In practice, it looks a bit like field rotation.

Comment by Marc Basti on July 7, 2012 at 6:00am

Greg, what would an over-corrected condition look like? Thanks, Marc

Comment by Greg Marshall on July 5, 2012 at 7:48pm

It is surprising how good it is without a flattener, but it's certainly not perfect and I'm worried that my William Optics "Flat 4" will over-correct it. If so, I may have to get something from Astro-Physics, which would be expensive.

Comment by Marc Basti on July 5, 2012 at 4:09pm

Looks like the test went well, some nice detail in there and stars look round in the corners. Bad case of aperture fever lol. Marc

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