waynemia
super member
Reged: 03/04/12
Loc: Springtown, TX
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Need some input on an Orion Short Tube 80
#5234475 - 05/22/12 05:29 PM
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I ordered a Short Tube 80 from Orion. My intent was to use it as a guide scope and a portable visual scope. I ordered the ST80A configuration with tube rings and Expanse eyepieces.
My dilemma is I don't get a crip sharp focus. I try to fovus on Venus and there are three crescents and I have to work to try to get them to converge. I look at Sirius and I get flares and not a nice round star. I get the same thing with Arcturus. I seem to be able to get Saturn to focus but it is so small, even with a barlow, I can't really tell if it is properly focused or not. I have tried the 9mm and 20mm that came with it as well as a 32mm Highlight and 5mm Stratus.
Orion sent me a replacement and it looks the same as the first one.
I am concerned about keeping the scope now. I have not tried the diagonal on anything else, I have a 10" dob I could try, but I can't focus without it, I don't have a 1.25 extension. I also HATE the image shift with the r&p focuser.
I also don't like the litte finder scope that came with it. You have to unscrew the front lens almost completely before it is focused.
Should I send it back and look at a different scope? Maybe the ED80? Or should i keep it and use it as a guide scope and not be so critical? I am very new and my first scope was the XT10i. I don't have focus issues with it, period. I have a little coma but that is not a big issue.
The flares on the ST80 are pretty objectionable to me and I don't know if it is going to be an issue for guiding. Smaller, dimmer stars will focus OK. The nice bright ones are not so good.
I could use some help so I can get these returned or pick something else. I know I see the ST80 used as a guide scope often.
Thanks,
Wayne
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tomchris
professor emeritus
Reged: 12/22/10
Loc: Connecticut, U.S.A.
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Re: Need some input on an Orion Short Tube 80
[Re: waynemia]
#5234542 - 05/22/12 06:13 PM
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Just return it and decide on another scope. You sound extremely unhappy about the whole thing. It may be a pain to have to do the return thing again but my guess is you'll be glad you did it in the long run. I'm sure everyone in this forum then can give you lots of suggestions for a replacement scope.
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oo_void
sage
Reged: 11/13/09
Loc: San Francisco, CA
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Re: Need some input on an Orion Short Tube 80
[Re: tomchris]
#5234564 - 05/22/12 06:33 PM
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My Orion ST80 is a great performer for a small and cheap Achro. You will see color fringing on brighter objects, but not as much as you describe. Also, your problem with the focuser can be fixed simply by tightening down the tension screws. For $100, it's probably one of the best buys in astro gear.
Have you verified that the problem isn't being caused by something else in your optical chain?
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EdTheEdge
Pooh-Bah
Reged: 04/10/09
Loc: Lomita, CA
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Re: Need some input on an Orion Short Tube 80
[Re: oo_void]
#5234639 - 05/22/12 07:15 PM
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Could be the eyepieces. Try some eyepieces that you know are good.
My ST 80 is a less than average scope optically, But it is quite fun to use for wide fields and it travels well, if only because I don't have to worry much about it. It's like my old Timex - it takes a licking and still keeps ticking. You can mount it on just about anything and it makes a fine terrestrial/spotting scope.
But it's not a Tak.
In the end If you think something is wrong with it return it.
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waynemia
super member
Reged: 03/04/12
Loc: Springtown, TX
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Re: Need some input on an Orion Short Tube 80
[Re: oo_void]
#5234648 - 05/22/12 07:20 PM
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I have tried two tubes, two diagonals, and four eye pieces. I am not sure what else I can try. My only reference is my XT10i and 8" Astropraph. Going from reflector to refractor, I expected nice, crisp stars with some color fringe on bright objects. Arcturus, Spica, and Sirius give me bloby flares. I may be overreaching for this scope. The ED80 is my second choice. I already have a glass solar filter and guiding rings for the ST80.
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waso29
sage
Reged: 05/12/10
Loc: Chi-Town, USA, mother earth
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Re: Need some input on an Orion Short Tube 80
[Re: oo_void]
#5234665 - 05/22/12 07:28 PM
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That is very odd especially on your 2nd replacement scope.
The ubiquitous ST80 is a pretty low maintenance refractor.
Are you able to focus on objects during the day?
Check out Astronomyshed's video on ST80 tweaks.
http://www.youtube.com/watch?v=Ylb7xnc_03U&feature=g-user-c
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waynemia
super member
Reged: 03/04/12
Loc: Springtown, TX
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Re: Need some input on an Orion Short Tube 80
[Re: waso29]
#5234693 - 05/22/12 07:36 PM
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Thanks for the link. I like his videos. I went through the whole set on the Atlas mount and the ST80 one. I can focus during the day. I tried the expanse eyepieces in my XT10i and the 32mm highlight and 5mm stratus which are both fine on the dob.
I am going to try again to night as well.
Edited by waynemia (05/22/12 07:37 PM)
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spaulmac
member
Reged: 03/31/10
Loc: Louisville, KY
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Re: Need some input on an Orion Short Tube 80
[Re: waynemia]
#5234793 - 05/22/12 08:30 PM
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Unfortunately the Short Tube 80s have become a caricature of themselves. One on a computerized mount got me back into amateur astronomy about a dozen years ago. I fell hard for the wide fields and I've been a refractor junky since, but frankly they are just not that great of scope. Yes they're a great deal for the money, yes they're fun; but people have begun to get a bit silly about them. The short focal length does nothing but add tons of CA to the bargain objective. Blackening the lens edges might help reduce the multiple images, but don't expect miracles.
Frankly since this is not your first scope, and if you mean it to be more than a guide scope, I'd recommend returning it and digging a bit deeper for a scope that will make the most of your seeing time.
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Binojunky
Carpal Tunnel
Reged: 12/25/10
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Re: Need some input on an Orion Short Tube 80
[Re: spaulmac]
#5234969 - 05/22/12 11:33 PM
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What do these things sell for? I think for the basic OTA its about $100, the factory has to make profit, then its to be shipped half way around the world, an import tarrif has to be paid for, then Orion make a profit, then if purchased from a retailer they need to make a profit, so they are probably spitting these things out of the factory for about $25.
I had one a few years back, spent a ton of time tuneing it up , mainly inspired by a guy called Bob Berta,I flocked, blackened lens edges, tried the lens in various orientations and configurations, a very small improvement for a lot of work, it is what it is, a cheap fast achromat,DA.
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spaulmac
member
Reged: 03/31/10
Loc: Louisville, KY
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Re: Need some input on an Orion Short Tube 80
[Re: Binojunky]
#5235196 - 05/23/12 06:30 AM
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Given what I've seen of a friend's Astro-Tech AT72ED, it provides a much more up-to-date interpretation of a small, wide-field refractor. Modern optics coupled with a smooth 2", dual-speed focuser (handy for such a short FL scope) and convenient built in dual Vixen mount and tripod foot.
As for the finder, I'd argue an optical unit on such a short FL scope is a waste of effort and that you might be happier with an inexpensive red-dot style finder.
Good luck.
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Jon Isaacs
Postmaster
Reged: 06/16/04
Loc: San Diego and Boulevard, CA
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Re: Need some input on an Orion Short Tube 80
[Re: waynemia]
#5235222 - 05/23/12 07:22 AM
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I have tried two tubes, two diagonals, and four eye pieces. I am not sure what else I can try. My only reference is my XT10i and 8" Astropraph. Going from reflector to refractor, I expected nice, crisp stars with some color fringe on bright objects. Arcturus, Spica, and Sirius give me bloby flares. I may be overreaching for this scope. The ED80 is my second choice. I already have a glass solar filter and guiding rings for the ST80.
Hi:
Over the years I have owned several ST-80s and currently own a.variety of smaller refractors and Newtonians of all sizes. This is my take:
I suspect you have unreasonable expectations for your ST-80 and refractors in general
Spica, Arcturus and Sirius, these are very very bright stars Are they "nice crisp stars" in your reflectors? I kind of doubt it.
I would not expect them to be clean, nice stars even in a very good scope under normal conditions. Sirius is low on the horizon and super bright, it is going to he messy. It is good to remember part of the equation is your eye, bright stars saturate the retina...
To test the optics of an ST-80, I would choose three doubles. If Castor and Algieba were reasonably clean splits, I would be satisfied, these might require about 80x. Splitting Izar would be a bonus but not something I would necessarily expect. It might require as much as 200x and decent seeing. This is a fast achromat so the false color will definitely be visible viewing these stars.
The st-80s I have owned have been decent scopes within the limitations of an 80mm f/5 achromat. Chromatic aberration is apparent at higher magnifications, field curvature is there at lower magnifications. It's a fun scope that should be good for what you want.
Enjoying any scope is about reasonable expectations. The path to perfection is long and expensive... And even a perfect scope is limited by its aperture.
Jon
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Don Trinko
Carpal Tunnel
Reged: 07/05/09
Loc: Ohio
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Re: Need some input on an Orion Short Tube 80
[Re: Jon Isaacs]
#5235226 - 05/23/12 07:28 AM
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I have had 2. They were ok but you do get what you pay for most of the time.
I had an AT66ED and it was a better scope but at 3x the price.
After reading this thread I have come to the same conclusion as Jon; you have unreasonable expectations for this scope. Send it back. All IMO; Don T.
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Binojunky
Carpal Tunnel
Reged: 12/25/10
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Re: Need some input on an Orion Short Tube 80
[Re: spaulmac]
#5235355 - 05/23/12 09:32 AM
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Given what I've seen of a friend's Astro-Tech AT72ED, it provides a much more up-to-date interpretation of a small, wide-field refractor. Modern optics coupled with a smooth 2", dual-speed focuser (handy for such a short FL scope) and convenient built in dual Vixen mount and tripod foot.
As for the finder, I'd argue an optical unit on such a short FL scope is a waste of effort and that you might be happier with an inexpensive red-dot style finder.
Good luck.
Agreed the AT72 ED is a great buy for the money, DA.
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waynemia
super member
Reged: 03/04/12
Loc: Springtown, TX
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Re: Need some input on an Orion Short Tube 80
[Re: Don Trinko]
#5235360 - 05/23/12 09:35 AM
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Last night I was able to get things to work better, I think. There seems to be a lot of slop between the focuser and the diagonal. I experimented with moving it around with the screws loose. This let me get a position that made things better and what I would consider reasonable. I am still on the fence about keeping it but at least I think it will be OK for guiding which was the primary purpose. I am still thinking of getting the ED80 instead. It should have less CA and it has a crayford focuser.
I only commented on the little finder because it came with it. This setup was $179 on sale.
I appreciate all the input.
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dan_h
Carpal Tunnel
Reged: 12/10/07
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Re: Need some input on an Orion Short Tube 80
[Re: waynemia]
#5235394 - 05/23/12 09:58 AM
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My dilemma is I don't get a crip sharp focus. I try to fovus on Venus and there are three crescents and I have to work to try to get them to converge. I look at Sirius and I get flares and not a nice round star. I get the same thing with Arcturus. I seem to be able to get Saturn to focus but it is so small, even with a barlow, I can't really tell if it is properly focused or not. I have tried the 9mm and 20mm that came with it as well as a 32mm Highlight and 5mm Stratus.
Orion sent me a replacement and it looks the same as the first one.
I have played with a number of these litte scopes and there is not much that can go wrong with them.
It may be that your problem with higher power views had to do with atmospheric seeing and also that the 5mm Stratus is not a great performer at f5.
Your low power views with the 20mm and 32mm may have highlighted some problems with your eyes. I know that what you have described is pretty much what I get when I am over tired. I get lots of astigmatism, flaring and multiple images when my eyes are not at their best. I recently used a 4" f6 refractor that I haven't had out for a couple of years and the images were absolutely terrible compared to how I remebered the scope. The only thing that has changed is my eyes.
dan
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tomchris
professor emeritus
Reged: 12/22/10
Loc: Connecticut, U.S.A.
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Re: Need some input on an Orion Short Tube 80
[Re: Binojunky]
#5235917 - 05/23/12 03:15 PM
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Quote:
Quote:
Given what I've seen of a friend's Astro-Tech AT72ED, it provides a much more up-to-date interpretation of a small, wide-field refractor. Modern optics coupled with a smooth 2", dual-speed focuser (handy for such a short FL scope) and convenient built in dual Vixen mount and tripod foot.
As for the finder, I'd argue an optical unit on such a short FL scope is a waste of effort and that you might be happier with an inexpensive red-dot style finder.
Good luck.
Agreed the AT72 ED is a great buy for the money, DA.
I recently bought an AT72 ED at the NEAF to use as a travel scope. I must admit I was amazed at the quality of it at a fairly low price.
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Chris_H
Post Laureate
Reged: 11/24/03
Loc: Norway
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Re: Need some input on an Orion Short Tube 80
[Re: tomchris]
#5235997 - 05/23/12 04:09 PM
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I got one when I bought Orions quide scope package and having owned a 80ST 6 years before, I didn't expect much. Boy was I blown away! My old model showed A LOT of blue and purple but this one hardly shows any at all. I'm not saying it's color free but neither is the 72ED! The main problem with these ST's are the lens spacers and the focuser. If you can fix them (not hard at all) you end up with a great little package for not a lot of money.
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tnakazon
super member
Reged: 06/26/10
Loc: Los Angeles
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Re: Need some input on an Orion Short Tube 80
[Re: waynemia]
#5237974 - 05/24/12 08:21 PM
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Last night I was able to get things to work better, I think. There seems to be a lot of slop between the focuser and the diagonal. I experimented with moving it around with the screws loose. This let me get a position that made things better and what I would consider reasonable. I am still on the fence about keeping it but at least I think it will be OK for guiding which was the primary purpose. I am still thinking of getting the ED80 instead. It should have less CA and it has a crayford focuser.
I only commented on the little finder because it came with it. This setup was $179 on sale.
I appreciate all the input.
Fortunately (or unfortunately in my case), the retail price of the Orion Short Tube 80-A (with OTA, rings and EP’s) was reduced starting this year from $229.99 to $199.99. I bought mine in December of last year - fortunately, it was on sale for $199.99, shipping was free, and I used a $10 off e-coupon.
I see that you're going through what I went through.
When I first tried out the Orion ST80A (like you, I bought the version with the OTA, rings and EP's), I was horrified to see planetary images that were sharp on one side, blurry on the other. All my scopes were Newtonians up to that point, so I thought refractors came out of the factory well collimated. Also, the draw tube was very loosely attached to the focuser and the dew shield was impossible to remove from the black plastic cell.
So I returned it for another ST80-A, but to my horror, found that the replacement was miscollimated as well (this time the blurry/sharp sides were reversed).
So I started doing research online on collimating a refractor. I bought a refractor cheshire collimator and saw two overlapping dot images when I looked through the collimation eyepiece. So I unscrewed the retaining ring, hit the sides of the black plastic cell holding the two elements, re-screwed the ring back on, rechecked the collimator and got a single dot image inside a concentric circle. Then I tested the scope again on the stars/planets and boom, no more blurry images.
However, I was still getting pinched optics - a bright defocused star at high power shows a slight triangular shape rather than a circle or oval. So when focused, a bright star does not show concentric rings around an airy disk, but three broken arcs representing the corners of a triangle.
No matter how many times I unscrew the retaining ring, hit the sides of the plastic cell holding the lenses, and rescrew the ring back on (loosely or only finger tight), I’m still getting pinched images.
So I started tweaking this scope further by actually removing the two objective elements from the plastic cell, and putting them back in again. I also tried realigning the focuser with the objective lenses by loosening the focuser assembly (held by 3 screws) and using the view from the Cheshire EP to get it recentered. I’m determined to resolve the pinched optics problem in this scope.
As Chris H in the previous post says, it’s all about tweaking the lens spacers and the focuser. And as Dave (BinoJunky) mentioned and I’m currently experiencing, you could spend (or waste) a lot of time trying to fix this scope.
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waynemia
super member
Reged: 03/04/12
Loc: Springtown, TX
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Re: Need some input on an Orion Short Tube 80
[Re: tnakazon]
#5238001 - 05/24/12 08:37 PM
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How do you change or modify the spacers? I do plan do do the Astronomy shed tweaks.
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Jon Isaacs
Postmaster
Reged: 06/16/04
Loc: San Diego and Boulevard, CA
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Re: Need some input on an Orion Short Tube 80
[Re: tnakazon]
#5238327 - 05/25/12 01:56 AM
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As Chris H in the previous post says, it’s all about tweaking the lens spacers and the focuser. And as Dave (BinoJunky) mentioned and I’m currently experiencing, you could spend (or waste) a lot of time trying to fix this one.
These are 80mm f/5 achromats, false color is a reality. Even the 80mm f/11 achromats, while much better than an f/5, show noticeable false color on brighter objects.
Jon
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