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RedIrocZ-28
Pooh-Bah
Reged: 09/18/05
Posts: 1175
Loc: Grand Rapids, Michigan
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I do not remember exactly how many frames this was but its over 400 for sure. I usually get a grainy look with anything under 400. ToUcam840k, 5fps, @ F/22. 
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Vic Menard
Post Laureate
Reged: 07/21/04
Posts: 3066
Loc: Bradenton, FL
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Is there any possibility that the elongated moon and shadow are the result of motion? In 80 seconds the planet rotates about 1/2 of 1-percent of the diameter, moon speed could be more. It's certainly possible that the elongation is a collimation artifact, but looking at the rest of the surface detail, I don't know... Are you convinced?
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auriga
scholastic sledgehammer
Reged: 03/02/06
Posts: 794
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Thanks Vic, this is a very clear and useful summary (except for the autocollimator section of course). I have marked this as a "favorite thread" so I can refer to it in the future.
(But if it reaches 300 posts with 100 diagrams I am out of here. :-) )
Regards,
Bill Meyers
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Jason D
Post Laureate
Reged: 10/21/06
Posts: 3293
Loc: California
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Quote:
But if it reaches 300 posts with 100 diagrams I am out of here. :-)
    
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XT10 classic with premium optics
Tri-knob CR2 with compression rings
Round Table Platform
4.5" StarBlast
6" StarBlast6
TV EPs
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RedIrocZ-28
Pooh-Bah
Reged: 09/18/05
Posts: 1175
Loc: Grand Rapids, Michigan
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Vic, I am pretty convinced that it is (was) a collimation problem. The raw frames show the elongated moon shadow.
Have not had a night with a shadow transit to verify now that I have circle shadows though. Hope to have the scope out tonight.
Vic, another thing that is bugging me, I know that the secondary is centered in the tube via measuring the distance from the center screw of the secondary mount to the tubes edge. Anyway, when you shine a lightsource down the tube, or are pointed at the moon, and you look down the tube and see the shadow of the secondary, the circular shadow is noticibly off center, like by 3/4" if not more. I have tried with a high intensity flashlight to see if the shadow changes location when the flashlight is held at different locations around the circumference of the tube, but the shadow doesn't move. Its always biased toward the focuser.
Is this normal?
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sixela
Postmaster
Reged: 12/23/04
Posts: 10848
Loc: Boechout, Belgium
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Yes. There are enough threads about diagonal offset elsewhere not to pollute this master thread with a more thorough explanation  .
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400mm f/4.46 self made Dobsonian on Tom Osypowski equatorial platform
Orion Starblast (114mm f/4 reflector, Alt/Az)
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RedIrocZ-28
Pooh-Bah
Reged: 09/18/05
Posts: 1175
Loc: Grand Rapids, Michigan
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sixela, you're right. Mods, remove my post if you feel necessary.
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