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jay52
Carpal Tunnel
Reged: 09/26/04
Posts: 2280
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Exodar:
Thanks for the compliments.
You are backing into what I was hinting at. I think the CG-AS is the mount to choose over the Atlas. By the time you will need an autoguider, you'll likely be at the point of wanting something better than the Atlas anyway. The Atlas is a sturdier mount than the CG-AS, but not necessarily better from the standpoint of imaging. The Atlas, from most of what I've heard, has some rather high periodic error which would reek havoc on an autoguider anyway. While I think there is some advancements being made with this mount, particularly with the EQ-6 GOTO stuff, I think by the time you add all that up you could have a Losmandy GM-8 anyway. Or, for the price, a Vixen GP-DX would give some of the best precision around. In other words, I'd probably think of it this way...if you can't get the Losmandy or Vixen right now, then stick with the CG-AS, especially if you opt for a smaller refractor.
Regarding the Orion 80mm ED, chromatic aberrations are not an issue. This scope is pretty much a true apo, with color correction that is every bit as good as other doublet apos that are three times the price. Many people are high on this scope because of the quality of the optics for their price. IMHO, it will give you the BEST images out of the box when compared to other OTAs...and...it will give you the best possible images for quite a while. In fact, such an OTA is seldom outgrown. When you are ready for longer focal length work, you'll likely keep always keep such a refractor for the times when you need the field of view. That's why I will likely die with my own small apo refractors...they will always have a purpose in my imaging "program."
Also, keep in mind that small apos can really push some magnification, so good planetary work is not out of the question. In fact, check out Don McCrady's recent Jupiter shot taken with a Tak Sky 90 (doublet apo refractor) and 5x Powermate on his webpage here:
http://dandkmccrady.home.comcast.net/
I would certainly look at the Orion 80mm ED with Celestron CG-AS mount. This will give you the best images possible within your budget range. If visual observing becomes important, I'd spend a few hundred bucks on an 8" or 10" dob. The more you keep the platforms separate, the more success you will have in both areas of the hobby.
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jay
www.allaboutastro.com
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Anonymous
Unregistered
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Jay...so let me see if I understand you correctly. You are saying that with an ED80 I can do some deep sky work!?! I pretty much knew it was great for planets, but thought deep sky was way out of the question. Heck, even if it did a little deep sky work I would swing that way just from all of the good things I hear about image quality from this scope.
Also, you feel like the ED80 on a CG-5 mount will still allow enough weight room for a good refracting guidescope and my 300D?
How do you feel about the GOTO version of the CG-5 mount? Worth the extra moola, or just forgoe that and spend the money on a good guidescope?!?
ROB
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TeamGS
Post Laureate
.gif)
Reged: 01/20/04
Posts: 3073
Loc: Elk Grove, CA
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Hey Rob,
I can't add much to the discussion here, except that the ED80 will be better for imaging DSO's than planets. A larger aperture scope is generally better for imaging planets, due to it's inherent ability to handle higher magnification. For DSO's, however, you don't necessarily want high magnification or need large aperture. This isn't to say that an ED80 can't take good planetary images, the same way that I wouldn't say that a 20" RC can't take great DSO images! 
I personally would recommend the GOTO version, only because it will save you time. You will be spending enough time getting set up as it is. In fact, with my LX200, the high precision GOTO can center an object on the CCD that I am not even able to make out visually.
Regards,
Gary
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Celestron 80ED
Losmandy G11
NexStar 80
Starlight Xpress SXV-H9
SXV guidehead, ToUcam 840
http://www.teamgs.org/astrophotography.htm
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Anonymous
Unregistered
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Man...I learn something new from this forum everyday! I love it. It is paying off in dividends! I would have already purchased the wrong scope and regretted it if I wouldn't have found this website.
Now that I understand the potential power of Autoguiding, I have my sites set on the Celestron CG-5GT mount. I see that Celestron offers an APO 80mm Refractor which I would assume is the equivalent (if not the exact same) as the Orion ED80. The only difference I see is that the Orion has a Crayford Focuser and the Celestron scope sports a Rack and Pinion Focuser.
Can someone explain the difference?!? Pros...Cons...
ROB
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DaveC
Pooh-Bah
Reged: 11/27/03
Posts: 1316
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Quote:
But I am scared of the refractors. What about Achromatic Aberration?!?
if i had ONE choice to recommend a type of telescope to learn astrophotography on it would be a short focal length refractor. so nothing to be afraid of.
as far as chromatic abberation is concerned... yup the short f/l achros have a ton of color that is for sure. they can be controlled by using certain filters. for example here is some photos i took with the orion 120st when i was learning. i used a orion skyglow filter to help control the CA.
http://www.cloudynights.com/photopost/showphoto.php?photo=620&password=&sort=7&thecat=500
http://www.cloudynights.com/photopost/showphoto.php?photo=689&size=big&password=&sort=7&thecat=500
both of these photos are fairly early in my learning curve. as yo can see the purplish halos are fairly well controlled using the orion skyglow filter. just as an FYI the orion skyglow filter performed better at eliminating CA than the orion v-block filter did and it had the added benefit of controlling light pollution. the biggest drawback of using an fast achro is focus is never going to be perfect. it simply cannot bring all of the spectrum to a fine focus point.
another option is to image in black and white using a deep red filter to control CA.
one last thing i feel you should know about using a digital rebel is that some nebula will be out of reach unless you modifiy it to remove the internal IR cut filter. but it can certainly take you far into the learning curve. so dont worry about it till later =)
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Anonymous
Unregistered
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Those pictures are pretty darn good in my opinion, but I can definitely see the CA. So I think it is just a wise move to go for the APO scope if I am already prepared to part with the cash...
I have read a lot about people removing the IR filter in their 300D. I am just not prepared to do that since I will continue to use it for standard photography. If I get into it at that level, I will probably just purchase a dedicated CCD for my scope.
You mention "the biggest drawback of using an fast achro is focus is never going to be perfect. it simply cannot bring all of the spectrum to a fine focus point"...does that hold true for the APO as well?
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jay52
Carpal Tunnel
Reged: 09/26/04
Posts: 2280
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Exodar:
You know those pictures you were looking at on my website. Most all of them were taken with a 4" apochromatic refractor. The Orion or Celestron 80mm ED is not far away from the scope I used. Of course, it does take some experience to capture images of good quality. In other words, the scope will not limit you to great images...the mount and your own ability might.
Basically, you choose a scope that gives you the field of view you want. A small refractor will give you a wide field of view as compared to longer focal length instruments. So, it will give you shots of larger field of stars and nebulae, larger galaxies, etc. Because you aren't shooting at much "magnification," it makes it easier to obtain these objects too. In other words, alignment, wind, human, and mount errors are less likely to screw things up. I'm not going to say aperture size isn't important, but generally speaking a camera is quite sensitive with most scopes, even those that possess small apertures. An 80mm scope is plenty large enough to give you some really deep images of the sky.
After you've chosen a scope with the focal length you want, then generally you choose the best optics you can get in that size. That's why I mentioned the Orion 80mm ED (yes, the Celestron is susposed to be very similar). It has really great optics for the price.
But don't take my word for it. Look at lots of pictures on the Internet. Make note of what images are taken with what equipment. Do a search on the Orion 80mm ED refractor to see what images have been taken with it. You'll likely be stunned...but even better, most of the images you see taken with this scope only scratch the surface of the potential of the scope. This is because imagers with great skill generally use more expensive scopes than this. Put the 80mm ED in the hands of somebody like a Matt Russell (www.telescopes.cc) and you'd likely be shocked with the result.
Like I said before, if you get that OTA, it will perform much better than anything else in the system.
As for the mount, it's a good value. You'll eventually want something better, but it'll take a good long while to get to that point.
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jay
www.allaboutastro.com
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Rushwind
Carpal Tunnel
Reged: 03/11/04
Posts: 2133
Loc: Newark, CA
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exodar,
Here's a photo of my long-exposure imaging rig.
It's an Orion 80mm ED refractor sitting atop a Celestron CG-5GT, with an Orion 80mm short tube refractor (achromatic) as a guidescope.
This rig just works. No problems with chromatic aberration due to the ED lens of the imaging scope. The autoguider (an SBIG ST-4, definitely what I'd look for once you get to that point) has no trouble keeping up with the mount's periodic error. I've had imaging sessions that ran well over 3 hours (I did a run of 60min, 45min x2, then several 20min of M31 in a single night), with no errors and no trailed stars.
The mount goes for $700 list. You may be able to find one cheaper or used.
The ED80 sells for $499 list from Orion, $419? list from Celestron, $424 in Orion's clearance section. You see these come up on the used market, too.
The only reason I hadn't suggested the CG-5GT/ED80 combo (both pieces of which I think you'll keep for quite some time) originally is because they list for $1200, and your (original) budget was $500. If you shop carefully, you can probably pick the pair up for closer to your $1000 budget.
The ED80 is a superb visual performer; in a side by side test (performed by myself and erik, another CNer) against a ST120, the ED80 held its own. Stars look like sugar scattered on black velvet.
I don't use my ED80 as a planetary imaging scope, but that's only because I have a larger 8" Newt that is better at it. If all I had was the ED80, I don't think that I'd have complaints in this area.
The ED80 is lightweight enough to keep the CG-5GT nimble, which makes all the difference in an imaging setup.
In short, you won't be disappointed if you pick up this combo. It will provide a good base to learn about astrophotography. It will give you some gorgeous views of the skies as you learn your way around the constellations. Best of all, when you start doing long-exposure photography, you'll be able to use both the mount *and* the OTA.
Jimbo
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Order of the Unblinking Eye
G-11 D70 ST4 8"f/5 AT66ED (Rig)
I used to shoot film.
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Anonymous
Unregistered
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Jimbo...that is such a sweet looking rig! I can't wait to get mine purchased and setup. Curious...any reason why you opted for the ShortTube 80 over Orions 80mm spotting scope?:
http://www.telescope.com/shopping/product/detailmain.jsp?itemID=5222&itemType=PRODUCT&iMainCat=6&iSubCat=29&iProductID=5222
ROB
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Rushwind
Carpal Tunnel
Reged: 03/11/04
Posts: 2133
Loc: Newark, CA
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My original plan was to use my 8" Newt as a long exposure imaging OTA, so I bought the smallest guidescope I could. Got the OTA on the 'mart, rings and dovetail from the link you mention, total was *way* less than $285... (more like $135).
Turned out that the ST80/8" combo was too heavy, so I had to regroup and get a smaller imaging OTA. About that time, the ED80 was "extremely hard to come by", and there was a run on them here on CN; I think that half a dozen CNers bought ED80s within a month or two of each other. I picked one up on Orion's "clearance" section (totally worth it; $424), and I haven't looked back.
Thanks for the compliment. 
Jimbo
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Order of the Unblinking Eye
G-11 D70 ST4 8"f/5 AT66ED (Rig)
I used to shoot film.
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Anonymous
Unregistered
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Jimbo...you have a gallery of your pics anywhere?
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Rushwind
Carpal Tunnel
Reged: 03/11/04
Posts: 2133
Loc: Newark, CA
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Sure, I have some shots on my website.
The planetary stuff was 95% shot through the 8" (I think I have 2 shots, one lunar and one solar, through the ED80).
The deepsky page is all shot through the (autoguided) ED80.
The widefield page is all SLR lenses. Some of it is piggybacked on the (autoguided) ED80 and some of it is fixed tripod (should be easy to tell which is which ).
Enjoy.
Jimbo
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Order of the Unblinking Eye
G-11 D70 ST4 8"f/5 AT66ED (Rig)
I used to shoot film.
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Michael Miles
professor emeritus
Reged: 02/11/05
Posts: 608
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Hi Rob:
Now to throw a wrench into the works...
Have you looked at the Meade LXD75 line? I'm in a rush right now, but cloudynights has a good review of the lxd75 mount and a shootout with the Celestron/Orion mounts in their review section. If you have a PC/laptop, you can autoguide plus much more with this mount. I just bought an LXD75 mount with the 6" Newtonain for $530 shipped - primarily for the upgrade path. I'll post more later, Michael
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LXD-75 w/
Stellarvue 102ED
Hardin 10" Newt
Antares 8" Newt
Meade AR-5
Meade N-6
Celestron 102mm refractor
Canon 300D, Meade DSI guiding
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Anonymous
Unregistered
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Jimbo...GREAT GALLERIES!! That ED80 sure does produce some clear images doesn't it...
Michael...you are not throwing a wrench into the works. I would definitely be interested in your opinion on the LDX75. I knew it was cheaper, but I couldn't verify it it could be autoguided, so I dismissed it.
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Anonymous
Unregistered
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Jimbo,
You have some very nice shots - the shot of M42 from Lake San Antonio is beautiful - I assume it is a much darker site than your home location.
Regards,
Harley
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Rushwind
Carpal Tunnel
Reged: 03/11/04
Posts: 2133
Loc: Newark, CA
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exodar: aw, shucks. I sure do like the ED80. I'm still growing into it; its ability to take sharp pictures is much greater than my ability to process them in Photoshop.
Harley: Thank you. Yes, Lk. San Antonio is a dark sky site. I only spent one "marginal" night there (clouds rolled in around midnight) late in the summer, but the Milky Way, M31, and the Double Cluster were all naked-eye there (darker than Coyote Lake, I think not as good as Shingletown). The skies in my backyard actually aren't too bad, all things considered; there's a streetlight across the street, but Brentwood's out on the edge of the sprawl. I keep meaning to go make friends with some of the local farmers -- *those* guys have some dark. I meant to reshoot M42 from here, but of course I only get shots at it in October and March...  I'm looking forward to a full spring/summer with the Rig.
Jimbo
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Order of the Unblinking Eye
G-11 D70 ST4 8"f/5 AT66ED (Rig)
I used to shoot film.
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badsnoopy
One star is enough
Reged: 12/20/04
Posts: 3556
Loc: La Porte, IN
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Hey Rob where are you located in Indiana? I have a Celestron C6-RGT if you wanted to see the CG5 goto mount.
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Robert
TV Genesis SDF
Losmandy G11
10x14 Roll roof observatory
Lumenera SkyNyx 2-2m
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