From: Mark Gaffney <markgaffney@me.com>

Date: February 15, 2010 3:58:05 AM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] about focus and seeing...


Hi Antonio, 

With respect to collimation you might like to look at this site;

http://www.astrosurf.com/legault/collim.html

This is what I`m now looking at. Metaguide autoguiding app for PC`s has a tool which should work using your TIS camera. I`ve found my TIS camera will no longer open on my PC & I`ve written to TIS about it twice now without a response to my first enquiry several days ago. I took the corrector (& secondary out of my C9.25 to clean a water stain) so it`s a special case. I`d had it out under tarps (polar aligned) which let the water at this time. I now have a Telegizmous scope cover which is doing a much better job. We had a hail storm recently which is beyond what the cover can cope with & I brought it in again & have had to try again with my polar alignment. The method for matching white colours when doing DSO imaging is to use a G2V star. I won`t pretend to know much about the practicalities myself but here`s a site which describes the process for you;

http://www.astropixels.co.uk/LRGB_primer.htm


Mark.

On 15/02/2010, at 7:37 PM, aa27100 wrote:



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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