johnnyha
Postmaster
Reged: 11/12/06
Loc: Sherman Oaks, CA
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Re: thoughts on the 12.5 Obsession
[Re: dscarpa]
#5707395 - 03/01/13 03:44 PM
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If I was buying a dob today i would definitely buy a used custom mirror scope, there are so many great bargains out there and many are scopes that simply have been hardly used by the owner. It is a true buyers' market.
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Starman1
Vendor (EyepiecesEtc.com)
Reged: 06/24/03
Loc: Los Angeles
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Re: thoughts on the 12.5 Obsession
[Re: dscarpa]
#5707477 - 03/01/13 04:49 PM
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The problem with the 12.5" Starstructure is it's no longer made. I checked it out while on my newt quest. David
http://www.starstructure.com/starstructure3_007.htm
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dscarpa
Carpal Tunnel
Reged: 03/15/08
Loc: San Diego Ca.
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Re: thoughts on the 12.5 Obsession
[Re: derekdann30]
#5707491 - 03/01/13 05:00 PM
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I saw that ad and called called Starstructure. I was told that they didn't make it any more. David
Edited by dscarpa (03/01/13 09:25 PM)
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jboege
super member
Reged: 03/15/05
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Re: thoughts on the 12.5 Obsession
[Re: dscarpa]
#5707657 - 03/01/13 07:20 PM
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I also was told the same months ago.
Quote:
I saw that ad and called and called Starstructure. I was told that they didn't make it any more. David
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Joe Bergeron
Vendor - Space Art
Reged: 11/10/03
Loc: Upstate NY
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Re: thoughts on the 12.5 Obsession
[Re: Starman1]
#5715606 - 03/05/13 11:30 PM
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Quote:
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The problem with the 12.5" Starstructure is it's no longer made. I checked it out while on my newt quest. David
http://www.starstructure.com/starstructure3_007.htm
They no longer make the scope, but they leave the page up on their site? Sloppy.
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Deb and Todd
sage
Reged: 05/23/06
Loc: Billings, MT
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Re: thoughts on the 12.5 Obsession
[Re: Joe Bergeron]
#5718826 - 03/07/13 04:59 PM
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I too started with 8" Orion and then purchased a 12.5" Obsession several years later.
I more than pleased with the Obsession. That said, i still use my 8" quite often for a number of different reasons, most of which I've posted at different times on this forum.
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George N
Carpal Tunnel
Reged: 05/19/06
Loc: Binghamton & Indian Lake NY
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Re: thoughts on the 12.5 Obsession
[Re: Deb and Todd]
#5728097 - 03/12/13 12:39 PM
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Teeter scopes are really nice, and the Starstructure (if still made) is also. Out-of-the-box they’re somewhat better scopes performance wise (aesthetics is too personal to comment on). However, what’s the wait time on these? You can probably get a new Obsession of any size in about two weeks, and adding a few improvements is not that big of a deal.
Of course the best deal on ‘wait time’ is to buy used. I got my 20-inch Dob the day after I saw it on AstroMart….. and the prior owner had done all of the “improvement work” that I wanted, except for a Glatter sling.
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ohioalfa64
member
Reged: 08/16/12
Loc: Ohio
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Re: thoughts on the 12.5 Obsession
[Re: George N]
#5730502 - 03/13/13 02:48 PM
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I have a 12.5 f/4 custom mirrored truss Dob. When it becomes time to upgrade to a larger Dob, I assume there is no point unless it is at least 15-16 inches. I don't want a larger one beyond that because I want to remain standing on ground. Prices for used truss dobs here on CN and on AM appear to be slightly over double for a 15-16 inch f/4 to 4.5 versus what I paid for the 12.5". All other components being equal is this a good standard rule for relative Dob value ($ Dob 12.5" x2+ = $ 15-16" Dob)?
Edited by ohioalfa64 (03/13/13 02:49 PM)
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Starman1
Vendor (EyepiecesEtc.com)
Reged: 06/24/03
Loc: Los Angeles
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Re: thoughts on the 12.5 Obsession
[Re: ohioalfa64]
#5730582 - 03/13/13 03:52 PM
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Quote:
I have a 12.5 f/4 custom mirrored truss Dob. When it becomes time to upgrade to a larger Dob, I assume there is no point unless it is at least 15-16 inches. I don't want a larger one beyond that because I want to remain standing on ground. Prices for used truss dobs here on CN and on AM appear to be slightly over double for a 15-16 inch f/4 to 4.5 versus what I paid for the 12.5". All other components being equal is this a good standard rule for relative Dob value ($ Dob 12.5" x2+ = $ 15-16" Dob)?
Well, unless you are very short, a 12.5" f/5 would also have allowed you to observe without a ladder or stool.
Keeping the focal length about the same to avoid a ladder goes:
15"--f/4.2
16"--f/3.9
18"--f/3.5
20"--f/3.1
Since prices go up tons with shortness of f/ratio (a 20" f/5 is 2/3 the price of a 20" f/3, for example), the scope prices will rise more than simply materials cost as they get larger because the f/ratios will shrink.
The f/ratio of the 15" and the 20" are both close to standards available from some makers today, but prices for a 20" f/3 are literally astronomical (though still less than a 16" SCT).
I would argue that though there is a 'little' difference in magnitude reach between a 12.5" and a 15", that difference is not worth spending a lot of money to achieve. I've looked through a LOT of scopes, and, for me, it takes at least an 18" to produce a noticeably better image of really faint targets. Even a 16" is only marginally better than a 12.5" at reaching faint targets. If you change, you want the extra weight and size to have been worth it, and moving up so little just won't slap you in the face with the difference to the point where you will think the big increase in weight was worth it. For me, 20" is the next logical step after 12.5", because you gain a magnitude and everything is really better in the eyepiece. 18" is OK. But 16" or smaller? I wouldn't bother.
Which is why I still have a 12.5".
But it does depend on the deal. I went from 8" to 12.5" for <$500 upcharge from the selling price of the 8". If you can get that kind of deal, then why not?
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Mike B
Starstruck
Reged: 04/06/05
Loc: shake, rattle, & roll, CA
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Re: thoughts on the 12.5 Obsession
[Re: Starman1]
#5730730 - 03/13/13 05:20 PM
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Even a 16" is only marginally better than a 12.5" at reaching faint targets. If you change, you want the extra weight and size to have been worth it, and moving up so little just won't slap you in the face with the difference to the point where you will think the big increase in weight was worth it.
I'd agree with that appraisal, with one exception; if one wished merely to *optimize* their scope for their ability to use & enjoy, why not go for the scope that is the most aperture as well as the most weight & size one can manage, for the max budget one can support?
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...because I want to remain standing on ground
Another excellent point of consideration- one with which i'm 100% into myself!  So one could, logically, look at max EP height- then consider a chart of ladderless size+FR options, precisely as Don posted (above)... then pick the aperture/F# where your budget yells "uncle".
If that happens to fall at a 2" aperture bump from where you are, or 3", or 4"- who cares? You now have a max-scope that fits YOU as best as can be done. Nothin' left layin' on the table.
Then go out & enjoy it!
The Dob in my sigline is the result my own, personal version of precisely this selection process.
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Aquarist
professor emeritus
Reged: 08/27/12
Loc: Illinois
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Re: thoughts on the 12.5 Obsession
[Re: Mike B]
#5732108 - 03/14/13 11:51 AM
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Does a 12.5 inch dob require dark skies to reap the benefits of an upgrade?
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Starman1
Vendor (EyepiecesEtc.com)
Reged: 06/24/03
Loc: Los Angeles
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Re: thoughts on the 12.5 Obsession
[Re: Aquarist]
#5732251 - 03/14/13 01:23 PM
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Does a 12.5 inch dob require dark skies to reap the benefits of an upgrade?
An upgrade to the 12.5" or an upgrade in size? Not clear.
But if you mean upgrading in size, there is a general truism in telescopes:
the larger the scope, the fainter the objects seen, regardless of light pollution.
I live in LA, and believe me, my night skies are REALLY light-polluted. I often say my night skies are orange, what color are yours?
Yet, my 12.5" simply blows away my 5" Maksutov with what can be seen.
In dark skies, M13 is resolved in the 5", but in the city it is merely a dull glow with no resolution (well, maybe a few outlier stars). The 12.5" resolves M13 to the core in the city and shows the small galaxy NGC4617 in the outskirts of M13 in a dark sky. Either place, the 12.5" simply shows more. The City view of M13 in the 12.5" is better than the country view of M13 in the 5".
So, aperture is aperture. No matter where you are, a larger scope goes deeper. Of course the larger scope has the same advantage in a dark sky and will show you even more.
At some point, though, you will reach a maximum size for your vehicle or your budget. But unless you have other requirements for use (such as being able to lift the entire scope and take it out on the patio), bigger scopes will show you more.
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Pinbout
Post Laureate
Reged: 02/22/10
Loc: Montclair
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Re: thoughts on the 12.5 Obsession
[Re: Starman1]
#5732303 - 03/14/13 01:59 PM
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I often say my night skies are orange, what color are yours?
So that's your line to pick up girls?
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George N
Carpal Tunnel
Reged: 05/19/06
Loc: Binghamton & Indian Lake NY
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Re: thoughts on the 12.5 Obsession
[Re: Pinbout]
#5732497 - 03/14/13 04:14 PM
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A 12.5” can be a very nice size Dob to have. I have friends, a couple in their 70’s, who own a custom made high-end 12.5 Dob built around optics from the Orion 12.5 Newt/GEM that they originally bought and found too bulky. The Dob has two handles on it, so that he can pick the entire scope up and carry it a 100 yards to a good observing field (they live under a green zone sky). She brings the eyepieces, a table, chairs, and charts. Even with checking the collimation they are ready to observe in 2 or 3 minutes. They leave the scope assembled under a cover in their garage, and also it is an easy fit into their RV. I think someone could do a lot of observing with a Dob this size.
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Jean Mario
member
Reged: 11/21/10
Loc: Québec, Canada, St-Jérôme.
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Re: thoughts on the 12.5 Obsession
[Re: dscarpa]
#5779643 - 04/05/13 01:36 PM
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It's best one !
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Mel M
super member
Reged: 05/04/08
Loc: southern Oregon
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Re: thoughts on the 12.5 Obsession
[Re: Thomas Karpf]
#5780487 - 04/05/13 08:47 PM
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If you're buying that NEW, you definitely want to look at the Starstructure 12.5" with a Carl Zambuto mirror. Currently $3495. WELL worth the additional $200 above the price of the Obsession.
http://www.starstructure.com/starstructure3_007.htm
For years Obsession has claimed the full thickness 2" mirror gave their 12.5" an advantage. Their web site said they didn't use those thin, bendy, potato chip mirrors.
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