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Robin,

Lens calibrations are done with the measured angle centered on the long axis with the camera's cross hair always centered between the two points being measured.

This evenings exercise will be an attempt to calibrate a 135mm lens using only Big Dipper star to star distances. A low altitude Sun image will test the calibration results.

Your 18Mp camera should provide 0.3 minutes of arc per pixel when using a 50mm lens. I avoid using wide angle lenses for CN purposes because of excessive distortion and higher minutes of arc per pixel values. Telephoto lenses are better for CN but have a limited field of view. 200mm and above lenses need only a single pixel multiplier making calibrating much easier.

Greg Rudzinski

Re: LADEE Moon Probe Puzzle
From: Robin Stuart
Date: 2013 Sep 19, 14:51 -0700
Greg,

I’m happy to send you the original image in all its 18Mp glory by a separate email.

Your Alkaid-Mizar sight looks quite promising. Are you scaling the measured distance by a single pre-determined factor or do you take account of the variation of the scale factor with distance from the centre of the image?

Regards,

Robin
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