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Andres,

The 200 mm lens was calibrated a few years ago by observation of a filtered Sun diameter at high altitude then confirmed with distant horizontal angle images and standard low altitude Sun observations at the beach seashore from a known GPS position.I don't keep calibrating each time I do DSLR CN. It is a one time calibration for each lens used. The 200 mm is the easiest to calibrate with a single minute of arc per pixel multiplier good through the very narrow field of view. DSLR cameras must be in manual mode for CN calibration and observations. Anything that changes focus from infinite will ruin images for CN purposes.

Greg Rudzinski

From: Andrés Ruiz
Date: 2017 Sep 29, 14:44 +0200

Hi Greg,

Did you use the SD in order to obtain the moa/px ratio?

If yes, did you fit the Moon diameter with a plotted circle for this?

Lower limb Moon = 95 px

Lower limb Moon = 391 px

Center Saturn = 1984 px

SD = 15.96'

0.0982 '/px

LD = 1593 px = 156.4326' = 2.60721º = 2º 3,6'

I use the free software paint.NET

Best regards,

-- 

Andrés Ruiz
Navigational Algorithms
http://sites.google.com/site/navigationalalgorithms/