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Equipment Discussions >> Equipment

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jrbarnett
Eyepiece Hooligan
*****

Reged: 02/28/06

Loc: Petaluma, CA
Re: A Quality set-up for double stars, $700 or less ?? new [Re: Jon Isaacs]
      #5791622 - 04/11/13 12:10 AM

Yup, the Double-double is a fairly easy target in a 60mm. Trapezium E and F, though, are not easy in a 3-incher. The are doable, provided that the scope is well-baffled and seeing cooperates. E and F are *much* easier in a 4" refractor; ~100-120x seems optimal. I find all unequal doubles doable in much smaller refractors than they are in larger scopes of other designs. I believe it has to do with the refractor's inherently better glare suppression. For example, I find Sirius B pretty easy in a quality 3" refractor at just under 100x. Read the double star forum posts about Sirius B. You'll see all kinds of crazy suggestions along the lines of it requiring 10" to 12" and high magnifications.

The thing about double stars is this: there are literally thousands of them visible in any sized telescope. Sure, a larger scope might let you split tighter doubles (but not always; just ask my club mates using 10" to 15" Dobs not being able to split Sirius when a 3" will do so), but there's always an equivalent aesthetic experience available in the smaller scope. In other words, you can find a double near the limits of a 3" scope that looks a lot like a dimmer pair at the limits of a 12" scope. In fact, I think doubles are almost more fun in a small scope less hampered by seeing. That said, 4" is a good compromise if you can swing it within your budget.

Regards,

Jim


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: A Quality set-up for double stars, $700 or less ?? new [Re: jrbarnett]
      #5791936 - 04/11/13 08:54 AM

Quote:

I believe it has to do with the refractor's inherently better glare suppression. For example, I find Sirius B pretty easy in a quality 3" refractor at just under 100x. Read the double star forum posts about Sirius B. You'll see all kinds of crazy suggestions along the lines of it requiring 10" to 12" and high magnifications.




Sirius B is still widening... getting easier, 10 years ago it was 6 arc-seconds instead of 10 and much more difficult. When was the last time you split Sirius in an 80mm?

Jon


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DaveJ
Carpal Tunnel
*****

Reged: 01/07/05

Loc: NE Ohio
Re: A Quality set-up for double stars, $700 or less ?? new [Re: jrbarnett]
      #5792038 - 04/11/13 10:04 AM

Quote:

Good luck finding a 4" f/15 achromat and a suitable mount for $700. In fact, good luck finding a new or used 3" f/15 with modern 1.25" focuser (rather than a 0.965" unit), at all.




Hi Jim,

Far be it for me to reveal something of which you are not aware, but here is a brand spanking new 101mm f/15 with what to me looks like a 1.25" or 2" focuser: link. The cost might be a problem, though...


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buddyjesus
Carpal Tunnel
*****

Reged: 07/07/10

Loc: Davison, Michigan
Re: A Quality set-up for double stars, $700 or less ?? new [Re: DaveJ]
      #5792550 - 04/11/13 02:46 PM

those skylight scopes are a wonderful scope to look at. I believe it is best to order in advance as they sold out of previous ones quickly. http://skylight.myshopify.com/

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Widespread
professor emeritus


Reged: 05/11/11

Loc: Bowling Green, Kentucky
Re: A Quality set-up for double stars, $700 or less ?? new [Re: buddyjesus]
      #5792565 - 04/11/13 02:58 PM

The brass counterbalance system looks interesting.

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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: A Quality set-up for double stars, $700 or less ?? new [Re: DaveJ]
      #5792590 - 04/11/13 03:15 PM

Quote:

Quote:

Good luck finding a 4" f/15 achromat and a suitable mount for $700. In fact, good luck finding a new or used 3" f/15 with modern 1.25" focuser (rather than a 0.965" unit), at all.




Hi Jim,

Far be it for me to reveal something of which you are not aware, but here is a brand spanking new 101mm f/15 with what to me looks like a 1.25" or 2" focuser: link. The cost might be a problem, though...




I think they are around $2000... big and long.... might as well get a 120mm Eon or SkyWatcher...

Jon


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DaveJ
Carpal Tunnel
*****

Reged: 01/07/05

Loc: NE Ohio
Re: A Quality set-up for double stars, $700 or less ?? new [Re: Jon Isaacs]
      #5792612 - 04/11/13 03:28 PM

Quote:

I think they are around $2000... big and long.... might as well get a 120mm Eon or SkyWatcher...




Me? I'm quite satisfied with my TEC 140.


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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: A Quality set-up for double stars, $700 or less ?? new [Re: DaveJ]
      #5792671 - 04/11/13 04:03 PM

Quote:

Quote:

I think they are around $2000... big and long.... might as well get a 120mm Eon or SkyWatcher...




Me? I'm quite satisfied with my TEC 140.




That was probably over the $700 limit too.

Jon


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mark379
sage
*****

Reged: 02/07/09

Loc: New Jersey
Re: A Quality set-up for double stars, $700 or less ?? new [Re: Jon Isaacs]
      #5793349 - 04/11/13 09:45 PM

Something similar to Pat's setup may be attainable. an ed 100 on a Astro tech voyager may be the ticket. If you buy used, you should be within your budget. An ED 80 might be a decent choice as well, but a longer f/l refractor works better IMHO.
Best,
Mark


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Jaimo!
Pooh-Bah
*****

Reged: 10/11/07

Loc: Exit 135 / 40° North
Re: A Quality set-up for double stars, $700 or less ?? new [Re: mark379]
      #5793609 - 04/12/13 12:12 AM

Would this scope fit the bill? 102mm f/11, I've had my eye on this for a while...

http://handsonoptics.com/index.php?main_page=product_info&cPath=1_112&...

Jaimo!


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Astro One
member
*****

Reged: 02/20/13

Loc: San Bernardino County, CA.
Re: A Quality set-up for double stars, $700 or less ?? new [Re: Jon Isaacs]
      #5793658 - 04/12/13 01:00 AM

Thanks to everyone who helped out with my query. I am now in the process of buying a 4" Orion 100ED for $400 (recommended to me by Jim Barnett). Also, I am also working on getting a Vixen Porta Alt/Az mount. Next I'll need a dovetail mounting plate, scope rings, and, an 8x50 RACI finder. I've already got eyepieces. $700 or less... well maybe just a pinch more! Thanks again for all of the help, Steve

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Jon Isaacs
Postmaster
*****

Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: A Quality set-up for double stars, $700 or less ?? new [Re: Astro One]
      #5793677 - 04/12/13 01:13 AM

Quote:

Thanks to everyone who helped out with my query. I am now in the process of buying a 4" Orion 100ED for $400 (recommended to me by Jim Barnett). Also, I am also working on getting a Vixen Porta Alt/Az mount. Next I'll need a dovetail mounting plate, scope rings, and, an 8x50 RACI finder. I've already got eyepieces. $700 or less... well maybe just a pinch more! Thanks again for all of the help, Steve




Steve:

Sounds like a good rig... agenda astro generally has good prices on rings and dovetails.

Jon

Edited by Jon Isaacs (04/12/13 03:02 AM)


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buddyjesus
Carpal Tunnel
*****

Reged: 07/07/10

Loc: Davison, Michigan
Re: A Quality set-up for double stars, $700 or less ?? [Re: Jon Isaacs]
      #5793706 - 04/12/13 01:42 AM

your gonna love it! I will upgrade my achromat after I buy a big scope to complement it.

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