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Aperture comparison sketches

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#1 matman-1

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Posted 09 September 2009 - 10:12 AM

I’m not sure this is the right forum for this kind of question but I give it a try. I’m am very curious of visual comparison of different aperture. For example sketch of a galaxy/cluster in 4 inch, 6inch, 12 inch newt. There is the classical comparison of M13 on obsessions website but them being a vendor not sure how much truth it is in it.

appreciate any answer, tips, links.

Clear skies to you all!

#2 Jeremy Perez

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Posted 09 September 2009 - 10:21 AM

Hi matman, if you go to the Deep Sky Archive, you can search for an object, such as "Messier 13" or "NGC 7331", etc., and see sketches from contributors using a variety of telescopes/binoculars/naked eye. The only problem will be that different sketching styles, observing skills, and viewing conditions may have as great an effect on what the sketch shows as the aperture does. Still, it is very informative of what is possible given a particular scope and definitely fascinating to see what other observers discern.

#3 rolandlinda3

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Posted 09 September 2009 - 10:44 AM

I have sketched several objects to compare apertures if that is any help. You can peruse the gallery listed on the signature. Go to the Eagle Series to see the most recent comparison with eps as well as astro video.

#4 matman-1

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Posted 10 September 2009 - 08:21 AM

spent the last half hour gazing at sketches at the deep sky archive, excelent stuff, thanks Jeremy. could quite find the eagle series on your link there roland, but I keep looking, once again thanks for your links.

#5 TenthEnemy

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Posted 10 September 2009 - 04:19 PM

I like the idea of sketching the same object in different apertures in the same night for comparison. I've never done this because the jump would be from 80mm to 10 inches which seems a little ridiculous without something in the middle.

I could make a comparison between a 60mm and 80mm but that hardly seems interesting.

#6 rolandlinda3

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Posted 10 September 2009 - 07:32 PM

sorry.... here it is.

#7 JakeSaloranta

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Posted 11 September 2009 - 12:56 AM

Years ago when I was still a novice I wrote an illustrated article about the differences of 4" and 8" telescopes when viewing deep sky objects. I can see if I can find the comparison sketches from my hard drive.

I have hundreds of objects sketched with 3" and 8" but they are hardly comparable (often using the 3" under very dark skies and 8" under suburban skies).

The only real thing that comes to mind (not directly related to aperture but gives a so-so demonstration) is visibility of M42 with 3" refractor and UHC filter:

http://www.kolumbus....ky/UHC/UHC.html

/Jake

#8 JakeSaloranta

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Posted 11 September 2009 - 01:13 AM

Here are a few rough comparisons (don't take them too seriously)

Posted ImagePosted Image
Messier 27 with 3" refractor and 8" reflector

Posted ImagePosted Image
Messier 67 with 4" reflector and 8" reflector

Posted ImagePosted Image
Messier 57 with 8" reflector and 12" reflector

Posted ImagePosted Image
Messier 51 with 3" refractor and 8" reflector

#9 Dr Morbius

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Posted 11 September 2009 - 10:18 PM

Nicely done sketches, Jake! Really gives a good impression of what you see with different apertures.

#10 phxbird

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Posted 12 September 2009 - 08:36 AM

It is interesting! The M57 sketches reveal something kind of cool though it is in a different field than sketching. The view with the 12" reflector is virtually the same as with my 6" refractor and a CCD camera using a 45 second exposure! I have used a technique where I take an image with CCD and then sketch it from the monitor. It is definitely not for science but for aesthetics!

#11 Reverie

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Posted 26 September 2009 - 07:42 AM

Some Jupiter sketches
http://alpo-j.asahik...sp.htm#Section4

#12 joelimite

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Posted 26 September 2009 - 02:52 PM

Jake, those aperture comparison sketches are great. Now you've got me scheming for a 12" reflector so that I can see the center star in M57 :jump:

Personally, I would love to see some galaxy sketches from a 16" or larger scope. I've tried searching the forum, but didn't have much luck. Anyone know of any?

#13 JakeSaloranta

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Posted 27 September 2009 - 02:37 AM

Personally, I would love to see some galaxy sketches from a 16" or larger scope. I've tried searching the forum, but didn't have much luck. Anyone know of any?


Try deep sky sketches by Iiro Sairanen: Iiro's DeepSky Sketches

He has hundreds of most excellent deep sky sketches made with 16", 18" and larger telescopes.

/Jake

#14 CarlosEH

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Posted 27 September 2009 - 07:20 AM

Aperture will always win in the visibility of astronomical objects (e.g. resolution) assuming diffraction-limited optics, collimation, and the atmosphere (seeing). This does not imply that a small aperture instrument cannot provide excellent views of the heavens. This forum has had posted many excellent observations made using small aperture instruments in the past and present. 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

#15 John K

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Posted 27 September 2009 - 10:49 AM

I just recently posted a ngc galaxy sketch.It is labeled Ngc 891.Here it is this was in mag 6.7 skys I used a 15" dob and a 13mm Ethos Mag=140X

Attached Files



#16 joelimite

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Posted 27 September 2009 - 11:28 AM

That's a stunning sketch, John. And Jake, thanks for the link. There are a lot of great sketches there that definitely prove, for galaxies at least, that aperture rules. Someday, when I've got a vehicle to tow the thing, I plan on getting a giant Dob so that I can enjoy similar views myself.

#17 Jeff Young

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Posted 27 September 2009 - 04:45 PM

Personally, I would love to see some galaxy sketches from a 16" or larger scope. I've tried searching the forum, but didn't have much luck. Anyone know of any?


Posted Image

Posted Image

Posted Image

Posted Image

More at http://www.rokeby.ie...s/sketches.html

Cheers,
-- Jeff.

#18 joelimite

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Posted 27 September 2009 - 05:46 PM

Those are beautiful sketches, Jeff. Thanks for the post and for the link. M33 in your 16" really puts the faint gray blob I see in my 8" to shame.

#19 HellsKitchen

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Posted 27 September 2009 - 10:28 PM

Great Sketches Jeff! I saw the dust lane in NGC 3628 with my 12" back a year ago but missed out on it this year due to constant cloud and smoke haze.

#20 TenthEnemy

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Posted 28 September 2009 - 02:14 AM

Here's M27, It was a lot of fun doing this sketch, so expect more like it in the future.

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#21 Reverie

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Posted 28 September 2009 - 05:49 AM

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? :jump:

#22 vennard

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Posted 28 September 2009 - 07:54 AM

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

#23 Ragaisis

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Posted 28 September 2009 - 10:13 AM

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. :smirk:

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

#24 Hrundi

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Posted 28 September 2009 - 10:34 AM

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.

#25 CarlosEH

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Posted 28 September 2009 - 01:44 PM

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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