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Gray
professor emeritus
Reged: 01/31/11
Loc: Hixson, TN
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Re: Planet scope decision
[Re: Starman1]
#5635227 - 01/21/13 03:40 PM Attachment (28 downloads)
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Maybe you guys are right. I haven't really had anything decent in 7 years to observe with until now. I just wanna make sure y'all understand what kinda scale I was seeing. Don you make it sound like it was huge, but I saw different unless my barlow wasn't working right. I'm putting a pic on here that a fellow took with his 14" SCT Friday night. If you stand back 3 feet from the screen, that's about how big Jupiter was and how much detail I saw in the 8". If that looks right to you then I'll settle down. 
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tomharri
sage
Reged: 09/19/08
Loc: Arizona
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Re: Planet scope decision
[Re: Gray]
#5635256 - 01/21/13 03:56 PM
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That's about what I saw last nite in my 8"f/5 newtdob. Along the equator could see a little more of the 'festoons', and all the dark bands were a little more 'sharper' more clearly defined edges. Plus could only go to a 5mm lens=200x. So a little less than average seeing for around here.
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Starman1
Vendor (EyepiecesEtc.com)
Reged: 06/24/03
Loc: Los Angeles
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Re: Planet scope decision
[Re: Gray]
#5635419 - 01/21/13 05:39 PM
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Your drawing on my monitor was 1" across a circle of 36" radius (which has a diameter of 72", which is a circumference of approximately 226"), with the eye sitting at the center of the circle.
Each inch of the circumference of 226" is an angular change of 360/226 = 1.59 degrees, with the eye at 36" away.
Actually, at 330X, Jupiter was about 4.13 degrees wide (apparent), or about the same as your drawing at (rounding off) the distance of 14" from the screen.
If you saw that much detail, you were doing pretty good. That indicates your seeing was average or above average.
People consistently underestimate the size of Mars and Jupiter in their scopes, but rarely underestimate Saturn. Perhaps the appearance of the rings is the reason, but I think it's for the reasons I mentioned, with Seeing conditions and Expectations being the primary ones.
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Gray
professor emeritus
Reged: 01/31/11
Loc: Hixson, TN
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Re: Planet scope decision
[Re: Starman1]
#5666321 - 02/07/13 12:32 AM
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Well folks, I'm a little embarrassed to say that I neglected to buy anything discussed above. I went out of my way and ordered a 108mm ED iOptron Versa with a WO CF dielectric diagonal yesterday from OPT. It's an F6.1 ED scope with 660mm of FL using FPL51 glass. No where near a planet scope, but I intend on using the 8" F5 for that. I learned quite a bit from this post, and even ventured into automated focusing, but rested in widefield viewing and better resolution imaging with my DSI3. It's F-ratio & FL is what I have been looking for with my little camera. Just wanted to put that in here. Thanks again for all your help!
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Jeff Morgan
Post Laureate
Reged: 09/28/03
Loc: Prescott, AZ
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Re: Planet scope decision
[Re: Gray]
#5666727 - 02/07/13 09:52 AM
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Quote:
Well folks, I'm a little embarrassed to say that I neglected to buy anything discussed above. I went out of my way and ordered a 108mm ED iOptron Versa with a WO CF dielectric diagonal yesterday from OPT. It's an F6.1 ED scope with 660mm of FL using FPL51 glass. No where near a planet scope, but I intend on using the 8" F5 for that. I learned quite a bit from this post, and even ventured into automated focusing, but rested in widefield viewing and better resolution imaging with my DSI3. It's F-ratio & FL is what I have been looking for with my little camera. Just wanted to put that in here. Thanks again for all your help!
Fear not, it will do nicely for you and there is always another telescope around the corner.
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