From: "aa27100" <antonio.agnesi@unipv.it>

Date: February 15, 2010 1:37:53 AM MST

To: Astro_IIDC@yahoogroups.com

Subject: about focus and seeing...

I have one more question for all you experienced imagers: how do you judge one night is worthy spending time on imaging?

Sometime the planets occasionally show exciting details visually, but the vision is all but steady, and I hurry setting up everything only for later disappointment when image processing does not yield the desired results.

My own experience is that if I am unable to say the scope is perfectly collimated with visual star-test (because of turbulence-distorted, indiscernible diffraction pattern) imaging is a loss of time. Maybe this is only due to my own incapacity of finding with certainty the focal plane, anyway I am nearly convinced that if I am frankly unable to say the scope is collimated, it cannot deliver diffraction-limited images...

When I captured these Mars images the star-test Airy pattern was reasonably clear, confirming the scope alignment, and Mars focusing at the laptop's screen was snap-on even at f/36 (both by eye and the sharpness estimator).

What is your thought and your experience?

Thanks!

Antonio

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