From: Milton Aupperle <milton@outcastsoft.com>

Date: December 8, 2009 7:19:00 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] cold weather..


Mark;


On 8-Dec-09, at 5:53 PM, Mark Gaffney wrote:


Hi Milton,

I`ve got a lemonade & some ice-blocks here now! Talk about two different extremes of weather at different parts of the globe! Your Crab Nebula looks a little better than the previous one with the Grasshopper! (although I don`t have them here to compare side to side). Thanks for the details of exposures.


That won't help you though.


Those exposure times are what works for the Grasshopper EXHad CCD with my Astro Done E-Series filter and a Hutech IDAS LPR. Without the LPR filter, I need to use a different ratio of RGB exposures. With a different set of filters or a different CCD you would need different RGB exposure times.


You have to calibrate the camera and filters using a star that approximates the sun (a G2V star) to get your balances. That's what I have done and know that without the LPR I need to use ratios of L 1.0 R 1.7 G 1.0 B 0.85 and with my Hutech IDAs filter I need to use L 1.0 R 1.5 G 1.0 B 0.67.


These sites


http://www.astropix.com/HTML/I_ASTROP/CUSTOMWB.HTM


http://www.astrosurf.com/~buil/us/cmy/cmy.htm


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


covers the basics.


They`re beginning to make more sense to me due to a little more experience (though not really practical) with these things. I`m ordering an Atik FIRA 1 filter wheel on Christmas eve but it`ll be a while before I can get the Astrodon`s. With a bit of luck I`ll be able to take some B/W shots of one DSO or another this summer. It`d be nice to get some results of the moon to compare favourably with Howard`s using the Scorpion though. He seems to be the yard-stick..i.e. the other person posting moon images on the group with this camera. I can`t work out whether I`ve got some setting wrong but my fine focus whilst OK with the Flea 2 is lacking with the Scorpion...


I doubt it's a camera issue.


More than likely you have turbulence and aren't recognizing it as such. I have some nights where even with a 25 mm eyepiece, I can't achieve sharp focus visually with my eyes. With the camera it's a blurry mess. It took me about 12 months before I finally had a night of clear skies with very good seeing before I knew the difference between the two.


Milton J. Aupperle