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Reverie
sage
Reged: 03/27/08
Loc: Somewhere far far away
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Re: Aperture comparison sketches
[Re: CarlosEH]
#3361185 - 09/28/09 06:49 AM
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Jay's excellent observations of DSO's made using a 3" refractor and an 8" reflector display the advantage of aperture. We all suffer from aperture fever, but the bottom line is to use the instrument at your disposal to it's fullest potential.
Carlos
Hi, May I know the link? 
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vennard
member
Reged: 12/29/08
Loc: Montana
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Re: Aperture comparison sketches
[Re: TenthEnemy]
#3361308 - 09/28/09 08:54 AM
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So, if I am understanding the line of reasoning here, the real difference between a large aperture and a small one is not the ability to get greater magnification but the ability to have more light reach the eye at the instant of looking. Phxbird used a 6” and timed CCD imaging to gather the same amount of light, in order to get the same image quality, as just viewing thru a larger instrument. And looking at Jeff Young’s drawings from his 16”, the magnifications of 100-175s used were easily achievable by many smaller scopes. It’s that there is not as much light available to the eye to describe the resolutions as from the smaller scopes to “see“ more detail. Generally speaking I think most folks, and I would be included among them up to now, equate larger scopes with greater magnification, which I suppose is achievable, but only because of the light gathered that allow the optimal use of such magnifications.
So how does this apply to seeing the surface detail on the moon, for example? It’s sure bright enough.
Mike
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Ragaisis
sage
Reged: 05/16/08
Loc: Milwaukee, WI
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Re: Aperture comparison sketches
[Re: vennard]
#3361511 - 09/28/09 11:13 AM
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I attended my first public outreach/star party this weekend. The goal was to have 100 telescopes set up for the public to come by, ask questions and take a peek. It was under "white zone" skies.
That means that I got to take a look through a LOT of telescopes other than my TV-85. So I got to see what difference aperature makes since most of the scopes were trained on either the moon or Jupiter (the two main objects up that the public was interested in).
I found that the views of those two objects in my "little" APO refractor were as good or better than in a 6" achro refractor that was set up next to me, as well as some very large dobsonian light buckets and some schmidt-cass and mak-cass scopes of various sizes. In fact it was MUCH better than some larger scopes I looked through.
To be fair, I was able to see more banding on Jupiter in a large SCT next to me with similar magnification, but the owner of that scope thought that my image was "crisper."
I didn't do any sort of comparison on DSOs since it really WAS a white zone and only one large dob was set on M15. But the view through that scope was remarkably similar to what I get with mine under a bit darker skies.
So nobody was really seeing any more detail on the moon than I was in my 3.5" scope. I _could_ see the difference that a scope with 10 times the light gathering ability had when I looked at Jupiter. 
BTW, there was a little 2" Galileoscope set up (they were selling them for $20), and the view of the moon through that thing was remarkably good, too.
I wouldn't necessarily have believed any of this unless I saw it for myself.
YMMV,
Chris
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Hrundi
Carpal Tunnel
Reged: 02/06/08
Loc: Estonia
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Re: Aperture comparison sketches
[Re: Ragaisis]
#3361555 - 09/28/09 11:34 AM
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With bright objects, it's more a matter of increased resolution that makes the difference. This all depends on weather though. If the sky isn't cooperating, then it really doesn't much matter what you have.
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CarlosEH
Postmaster
Reged: 01/19/05
Loc: Pembroke Pines, Broward County...
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Re: Aperture comparison sketches
[Re: TenthEnemy]
#3361896 - 09/28/09 02:44 PM
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John,
An excellent example of what an interesting galaxy (NGC 891) appears like in a large aperture instrument under dark skies and using an impressive eyepiece. The talent of the observer must not be forgotten. Thank you for sharing it with us all.
Jeff- An outstanding example of different types of galaxies visible in a large-aperture (quality) instrument. Your observations show the advantage of light grasp and resolution for these targets. Thank you for sharing them with us all.
TE- Thank you for providing a perfect example of what an object (The Dumbbell Nebula (M27) in Vulpecula) appears as in different aperture instruments.
I believe that all of these observations should be placed in a book on what an observer can visualize using different aperture instruments.
Carlos
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markseibold
Carpal Tunnel
Reged: 01/19/08
Loc: Portland Oregon
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Re: Aperture comparison sketches
[Re: Reverie]
#3361954 - 09/28/09 03:11 PM
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matman
I would agree with all others here. Although I produced these two comparisons to show light pollution effects, they would suffice as examples to show, say a difference between a 60mm refractor and 10 inch Dobsonain. -M
www.markseibold.com
M42
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John K
Carpal Tunnel
Reged: 12/26/05
Loc: Vernon BC Canada
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Re: Aperture comparison sketches
[Re: markseibold]
#3362715 - 09/28/09 10:53 PM
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Matman You have captured a perfect example of what a dark site can offer,and made me realize how much I wish I were there.It is a real treat to be there with the whole universe at your eye and nothing to stop you but the aperture of your instrument.(And the weather of coarse)
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frank5817
Postmaster
Reged: 06/13/06
Loc: Illinois
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Re: Aperture comparison sketches
[Re: TenthEnemy]
#3363563 - 09/29/09 10:41 AM
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This is becoming a collection of great sketches from some of the best deep sky sketchers alive today.
Frank 
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matman-1
member
Reged: 12/15/08
Loc: Northern Sweden
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Re: Aperture comparison sketches
[Re: frank5817]
#3399797 - 10/20/09 09:40 AM
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Haven’t logged on for a while but I rely happy to see all your answers. JakeSaloranta amazing sketches, really happy to see comparison between 3 inch refractor and bigger reflector.
John K, nice pic with your 15 inch. and thanks for all the other posts aswell. Ive never looked at space with anything bigger than my four inch achro, but really looking forward to see at some messier object with 8 inch or bigger from a dark site in the future. man this is a great hobby!
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