RE: [APML] 8" Schmidt camera on Astromart

[Aplanatic@aol.com]

Thanks, Chuck and Chris for your inputs.  And welcome, Chris.  I've admired your film shots, close up, in the past and hear that you're doing some CCD work now.

Anyway, I also suspect that an f/2.5 Schmidt is a good trade-off, reducing the focal shift and film loading problems substantially while keeping the speed high enough for most purposes.  It turns out that a Schmidt corrector is easy to make for an f/2.5 camera, an additional benefit.  At f/1.5 the vacuum pan deflection method of making the plate is not precise enough and the residual chromatic dispersion of the plate starts to impact the resolution a bit, at least for unfiltered TechPan exposures.

Dave Rowe



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