Quote:

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Actually the focal plane shift for a 90" EFL paraxial lens imaging at 1.5 miles is 0.085" (image distance is 90.085"). Think you left out a zero
Mike

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Thanks Mike, sure did drop a zero.

- Dave

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Homemade 'scopes 8"f/7,6" f/5", 6"f/4, 4.25" Schief. 60mm Coronagraph,60mm H-alpha system, 4.25" White-light Solar Newtonian,solar spectroscope, 4.5" f/16 Schupmann Medial refractor, 14 Stellafane awards 7 in optics

Engineering = Taking what you have and making what you need.

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