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12" LX200 SCT vs. 12" Orion XT12

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#1 Psa19one

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Posted 22 November 2005 - 11:13 PM

I am thinking about doing some switcheroos with my telescopes (such is the fun of this hobby!) Because I'm thinking of spending between $1500 and $2000 on a quality 100mm refractor, I still want another 'scope for doing DSO observing (visual, not AP). I currently have a 12" LX200, but I'm thinking of replacing it with a 12" Dob (like the Orion XT12) and using the rest of the money to help finance the APO (either a Tak FS-102 or a ZenithStar 105mm APO).

So... aside from the tracking the LX200 provides, would the quality of views be similar in a 12" Dob as with the 12" LX200 (FL differences notwithstanding)? I've never peered through an XT12.

Thanks for your thoughts!

#2 Guest_**DONOTDELETE**_*

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Posted 23 November 2005 - 01:44 AM

would the quality of views be similar in a 12" Dob as with the 12" LX200 (FL differences notwithstanding)? I've never peered through an XT12.


I believe you must be aware of this. But for those lurkers.

The XT12 will give much wider views --- great for M31! However, it will give you a small image of a planet since the view is so panoramic.

The Meade at F10 will give you in comparison to the XT10 a tight view and a larger view of a planet in the image.

I think having a widefield refrator and a widefield dob may not be the best money spent as they do similar jobs. Your Meade and an apo would make a great combo!

Yet, if you really need to finance that APO and you do not mind giving up the fantasic GOTO and tracking --- GO FOR IT!

#3 jrcrilly

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Posted 23 November 2005 - 04:58 AM

The XT12 will give much wider views --- great for M31! However, it will give you a small image of a planet since the view is so panoramic.

The Meade at F10 will give you in comparison to the XT10 a tight view and a larger view of a planet in the image.


I dunno about "much wider" views. The Newt will top out at around 1.5 degrees (35mm Pan or 31mm Nagler), the SCT at about 1 degree (41mm Pan). The Newt's minimum magnification (and thus max FOV) is limited by the F ratio, while the minimum mag on the SCT is limited by the focuser size. Neither would be wide enough for M31 in dark skies.

For planets, a given eyepiece with a 2X Barlow in the Newt would give precisely the same image scale as the same eyepiece in the SCT. Maximum practical magnification (and thus image scale) will be exactly the same (disregrading any difference in quality of optics) - that's driven by the aperture which is the same.

#4 Psa19one

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Posted 23 November 2005 - 09:11 AM

OK... well, aside from FOV, how would you compare the optics in the newt with that of the SCT? Pretty much the same? There's more glass in the SCT, and it's harder to collimate. Other than that, and the diffraction spikes you get with the newt's spider, are there any significant differences visually speaking?

Also, isn't the newts central obstruction quite a bit smaller than the SCT?

#5 jrcrilly

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Posted 23 November 2005 - 09:31 AM

OK... well, aside from FOV, how would you compare the optics in the newt with that of the SCT? Pretty much the same? There's more glass in the SCT, and it's harder to collimate. Other than that, and the diffraction spikes you get with the newt's spider, are there any significant differences visually speaking?

Also, isn't the newts central obstruction quite a bit smaller than the SCT?


There are too many variables to easily evaluate them. The SCT will have a slightly curved field, while the Newt will have some coma. The SCT is quite a bit easier to collimate because there's only one surface to adjust and you can usually reach the adjustments while looking into the eyepiece. The optics are built to fill very different price classes so one might expect superor quality in that particular SCT compared to that particular Newt. The added light loss from the corrector may or may not be compensated for by the superior mirror coatings in the SCT. Orion doesn't spec the central obstruction but it's probably 25% or so while the 12" SCT will be about 33%. The SCT will have superior baffling. The SCT will probably require more attention to cooldown effects.

All the above differences will be subtle. Diffraction spikes will be obvious. Some folks don't like 'em, others aren't bothered by them.

#6 jfaaz

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Posted 23 November 2005 - 10:04 AM

Many people say that a Newt will provide better and brighter images than a SCT. Coma is not that much of a problem with an f/5 Newt.

A 4" Apo and a 12" Newt are a wining combination!

#7 BluewaterObserva

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Posted 23 November 2005 - 10:19 AM

The views at the same magnification, will be surprisingly similar in my experiences with two such beasts.

Your plan seems sound and somebody is going to get a good deal on an 12" LX200 to boot.

#8 jrcrilly

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Posted 23 November 2005 - 10:36 AM

The views at the same magnification, will be surprisingly similar in my experiences with two such beasts.


Nice job. That's what I was trying to say but using too many words! :lol:

#9 Nocturnal

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Posted 23 November 2005 - 02:08 PM

I think that any difference in optics can be 'learned to live with' between these scopes. Same aperture, same number of photons just about. I'd be concerned about the different ergonomics of the scopes. Observing with a Newt on a dob mount is very different than an SCT on a fork. Just from a navigational perspective (moving the scope while looking through the ep it will take time getting used to it because of the different positions and contortions. Plus the lack of automatic tracking and goto might be more painful than it appears now. But of course you've already decided that you're willing to give that up.

Have you considered getting a C11 on a gem mount?

#10 Psa19one

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Posted 23 November 2005 - 05:56 PM

Yeah, I've thought about going the C11 or even the 9.25 route, but I just can't see myself cutting back on aperature for DSOs when I've gotten used to seeing them with 12"! :p

The more I think about it, and the more I read, the more I think I might stick with my LX200 for awhile longer, bite the bullet, and buy the APO. Thanks for all you've shared! :)

#11 Chris G

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Posted 23 November 2005 - 09:03 PM

Kevin, my 12" LX200 compliments my SV115 nicely. :waytogo:

One thing I never liked about Dobs is collimating, I stink at it!! :lol: The SCT is a lot easier and holds collimation better.

#12 Psa19one

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Posted 23 November 2005 - 09:19 PM

When we finally buy a house (and get outta this apartment), I'll be able to set up a more permanent observatory in the back yard. When THAT finally happens, I will probably mount my premium APO on my LX200... ahhh... my dream... :praying:

#13 Psa19one

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Posted 23 November 2005 - 09:20 PM

Thanks, everyone, for your encouraging words!

#14 LLEEGE

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Posted 23 November 2005 - 09:30 PM

When we finally buy a house (and get outta this apartment), I'll be able to set up a more permanent observatory in the back yard. When THAT finally happens, I will probably mount my premium APO on my LX200... ahhh... my dream... :praying:

You could sell the LX and use the $$ for a down payment on a house. Wait a minute,if you sold the scope, you won't need a house! :lol:
On a more serious note, what would you mount that new Tak APO on if you sold the LX?

#15 Psa19one

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Posted 24 November 2005 - 10:10 AM

Not gonna sell the LX now ;) Anyhow, I do have a SkyView Pro mount I can use for the APO too.


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