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Equipment Discussions >> Reflectors

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robininni
scholastic sledgehammer


Reged: 04/18/11

Loc: Stephenville, TX
What's the largest size amateur dob available?
      #5921320 - 06/14/13 09:49 PM

Just curious. I know Starmaster makes 30". What's the biggest that wouldn't be some special abnormal custom order?

You know, such that one could purchase the structure for it from one of the usual places and one of the usual suspects would make the mirror?

Thanks,

Rob


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nevy
professor emeritus
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Reged: 02/07/12

Loc: UK
Re: What's the largest size amateur dob available? new [Re: robininni]
      #5921343 - 06/14/13 10:04 PM

I know a bloke called Nasa whose got a quite big one in space.

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robininni
scholastic sledgehammer


Reged: 04/18/11

Loc: Stephenville, TX
Re: What's the largest size amateur dob available? new [Re: nevy]
      #5921347 - 06/14/13 10:06 PM

Quote:

I know a bloke called Nasa whose got a quite big one in space.




Hence I put the following line in the original post:

You know, such that one could purchase the structure for it from one of the usual places and one of the usual suspects would make the mirror?



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plyscope
Pooh-Bah


Reged: 11/23/06

Loc: Perth, West Australia
Re: What's the largest size amateur dob available? new [Re: robininni]
      #5921354 - 06/14/13 10:09 PM

web page Normand Fullum telescopes

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nevy
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Reged: 02/07/12

Loc: UK
Re: What's the largest size amateur dob available? new [Re: robininni]
      #5921374 - 06/14/13 10:20 PM

Quote:

Quote:

I know a bloke called Nasa whose got a quite big one in space.




Hence I put the following line in the original post:

You know, such that one could purchase the structure for it from one of the usual places and one of the usual suspects would make the mirror






Oi , it was a joke ha ha , we'll I thought it was funny.

Edited by nevy (06/14/13 10:24 PM)


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Pinbout
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Reged: 02/22/10

Loc: nj
Re: What's the largest size amateur dob available? new [Re: robininni]
      #5921387 - 06/14/13 10:23 PM

Starstructure makes the smallest rigs for the largest mirrors with the horizon series. Up to 40".

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Mike B
Starstruck
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Reged: 04/06/05

Loc: shake, rattle, & roll, CA
Re: What's the largest size amateur dob available? new [Re: nevy]
      #5921611 - 06/15/13 02:04 AM

Quote:

Oi , it was a joke ha ha , we'll I thought it was funny.



Isn't that the scope that came with defective optics from the start?... had to fitted with after-market corrective lenses? You want somethin' like that from the usual supplier?



I think i'll be stickin' with the "usual" amateur suppliers- thanks.


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nevy
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Reged: 02/07/12

Loc: UK
Re: What's the largest size amateur dob available? new [Re: Mike B]
      #5921805 - 06/15/13 08:12 AM

Quote:

Quote:

Oi , it was a joke ha ha , we'll I thought it was funny.



Isn't that the scope that came with defective optics from the start?... had to fitted with after-market corrective lenses? You want somethin' like that from the usual supplier?



I think i'll be stickin' with the "usual" amateur suppliers- thanks.





Obsession perhaps
Before I get poked with another stick , I may need to clarify that this is another joke


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kfrederick
Carpal Tunnel


Reged: 02/01/08

Re: What's the largest size amateur dob available? new [Re: nevy]
      #5921828 - 06/15/13 08:46 AM

I am getting a meter blank soon I hope I think think that is the new big .

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Pinbout
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Reged: 02/22/10

Loc: nj
Re: What's the largest size amateur dob available? new [Re: kfrederick]
      #5921860 - 06/15/13 09:11 AM

did you get it anealed?

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turtle86
Pooh-Bah Everywhere Else
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Reged: 10/09/06

Re: What's the largest size amateur dob available? new [Re: robininni]
      #5921925 - 06/15/13 10:02 AM

Quote:

Just curious. I know Starmaster makes 30". What's the biggest that wouldn't be some special abnormal custom order?

You know, such that one could purchase the structure for it from one of the usual places and one of the usual suspects would make the mirror?

Thanks,

Rob




I'd contact Starstructure and Mike Lockwood.


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Fred1
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Re: What's the largest size amateur dob available? new [Re: robininni]
      #5922467 - 06/15/13 03:42 PM

Quote:

Just curious. I know Starmaster makes 30". What's the biggest that wouldn't be some special abnormal custom order?
...
Thanks,

Rob




I think going beyond 40" might, to some, be considered "some special abnormal custom order" so if you're looking to consider what the "biggest" normal is, then, IMHO perhaps 36" is the limit for normal. FWIW, I have first hand information from someone who was investigating such sizes. He posed many inquiries to owners of such, all of whom reportedly claimed one-man set-up, but when my friend actually saw them setting up, none of the owners of these large scopes set up these enormous scopes by themselves. YMMV.

ps: If you are considering going REALLY BIG, then you MUST see these scopes in person, even those in private observatories that never transport anywhere. I spent some time with Tom Clark's 42" when he was still in Chiefland. These are not scopes designed for the faint of heart.


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Astrojensen
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Reged: 10/05/08

Loc: Bornholm, Denmark
Re: What's the largest size amateur dob available? new [Re: Fred1]
      #5922488 - 06/15/13 04:10 PM

Take a look at this: http://www.cruxis.com/scope/scope1070.htm

I would think more than twice before attempting to get something that monstrously huge.


Clear skies!
Thomas, Denmark


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robininni
scholastic sledgehammer


Reged: 04/18/11

Loc: Stephenville, TX
Re: What's the largest size amateur dob available? new [Re: Astrojensen]
      #5922497 - 06/15/13 04:24 PM

Quote:

Take a look at this: http://www.cruxis.com/scope/scope1070.htm

I would think more than twice before attempting to get something that monstrously huge.


Clear skies!
Thomas, Denmark




Ha, yeah, that's too big to not be stationary in an observatory in my opinion!

Rob


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UmaDog
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Loc: Long Island, NY
Re: What's the largest size amateur dob available? new [Re: Astrojensen]
      #5922504 - 06/15/13 04:28 PM

The great thing about Hnssgen's scope is that it doubles as an RV: at the end of the night he can cover the mirror, tilt the OTA upright, and go to sleep curled up in the mirror box. As you can see, though, he keeps this bedroom rather messy: http://www.cruxis.com/scope/img1070/1070_InTrailer9.jpg

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gatorengineer
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Reged: 02/28/05

Loc: Hellertown, PA
Re: What's the largest size amateur dob available? new [Re: UmaDog]
      #5922557 - 06/15/13 05:05 PM

There are 50s running around now, you can check Mike Lockwoods site. There are probaby ten or more 40's out there some of which have a long history, JMI, and Swayze come to mind, that have been around for 20 years or so.

Budget trailer size are what becomes limiting.... I think much above 30 your enter a new class of massive, generally permanent scopes...


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jpcannavo
scholastic sledgehammer
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Reged: 02/21/05

Loc: Long Island New York
Re: What's the largest size amateur dob available? new [Re: robininni]
      #5924074 - 06/16/13 04:43 PM

Rob,
What are you thinking...!


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robininni
scholastic sledgehammer


Reged: 04/18/11

Loc: Stephenville, TX
Re: What's the largest size amateur dob available? new [Re: jpcannavo]
      #5924093 - 06/16/13 04:54 PM

Quote:

Rob,
What are you thinking...!




Haha! Just asking!


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JayinUTModerator
I'm not Sleepy
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Reged: 09/19/08

Loc: Utah
Re: What's the largest size amateur dob available? new [Re: robininni]
      #5924220 - 06/16/13 06:29 PM

I talked with Mike Lockwood in the spring and voice mail with Mike about a 36 inch dob. Still looking at it but it will be fall before I can move forward with it (stuff happens when you own some farms you lease out and have to do some replacement of equipment).

Anyway, Mike Clements is building and is almost done with his 70 inch reflector which is out at Steve Dobbs home/land. Here is a link to a post in February on that from my blog.


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turtle86
Pooh-Bah Everywhere Else
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Reged: 10/09/06

Re: What's the largest size amateur dob available? new [Re: Astrojensen]
      #5924416 - 06/16/13 09:01 PM

Quote:

Take a look at this: http://www.cruxis.com/scope/scope1070.htm

I would think more than twice before attempting to get something that monstrously huge.


Clear skies!
Thomas, Denmark




I think a scope that size would be fine in a permanent observatory, but I'd definitely think twice about trying to transport one. I'd also think twice about using a scope that size for solar observing, as shown in one of the pics. I'd be concerned that with the tiniest flaw in that solar filter, one's face would melt like a candle as in that scene from Raiders of the Lost Ark.


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Astrojensen
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Loc: Bornholm, Denmark
Re: What's the largest size amateur dob available? new [Re: turtle86]
      #5924834 - 06/17/13 03:28 AM

The problem with a scope this size is that an observatory is going to be incredibly expensive, simply because of the huge size and amount of material needed for its construction, not to mention the machinery and hours needed.


Clear skies!
Thomas, Denmark


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Jason D
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Reged: 10/21/06

Loc: California
Re: What's the largest size amateur dob available? new [Re: Astrojensen]
      #5924845 - 06/17/13 03:40 AM

Those who can afford a 70" reflector should not have any problem affording an observatory

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Astrojensen
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Reged: 10/05/08

Loc: Bornholm, Denmark
Re: What's the largest size amateur dob available? new [Re: Jason D]
      #5924850 - 06/17/13 04:04 AM

I'm not so sure about that. We do tend to want to maximize aperture and totally forget everything else.

Also, making the scope portable and not needing an observatory can suddenly either cut the total price in more than half or almost double the available cash you can spend on aperture.

No matter how we look at it, observatories are expensive. And in many places, they require permittance and must follow building regulations, adding complexity. A domed observatory for a 40" f/5 scope is massively huge, the size of a normal family house.


Clear skies!
Thomas, Denmark


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careysub
Carpal Tunnel
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Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: What's the largest size amateur dob available? new [Re: turtle86]
      #5924857 - 06/17/13 04:17 AM

I have thought that if you want to make a really huge Dob that it should be housed in a permanent observatory along the lines of the MMT on Mt. Hopkins:

http://www.hposoft.com/MMTImages/Observatory/ModelMMT.JPG

The entire structure rotates with the telescope (although the outer structure is isolated from the telescope mount) with clam shell doors covering the entire front. This allows a fixed elevator chair mechanism to provide easy seated viewing.

This could work even if the telescope itself is designed to be "mobile" (has wheels and can move). It would be rolled into the observatory and then secured rigidly in place.


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careysub
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Reged: 02/18/11

Loc: Rancho Cucamonga, CA
Re: What's the largest size amateur dob available? new [Re: Astrojensen]
      #5924859 - 06/17/13 04:21 AM

But you need a place to keep the giant mobile telescope anyway.

To some extent this is an unavoidable expense.

And you need to move it if it is to be really mobile - a huge trailer and a big truck, or else a U-Haul moving van, or similar.


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BluewaterObserva
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Re: What's the largest size amateur dob available? new [Re: careysub]
      #5925847 - 06/17/13 04:07 PM

I have a 30" on a GEM in my obs. I thought I wanted a 1 meter, but the 30" really was already bite'n off more than I could really chew.

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robininni
scholastic sledgehammer


Reged: 04/18/11

Loc: Stephenville, TX
Re: What's the largest size amateur dob available? new [Re: BluewaterObserva]
      #5926464 - 06/17/13 10:19 PM

Quote:

I have a 30" on a GEM in my obs. I thought I wanted a 1 meter, but the 30" really was already bite'n off more than I could really chew.




Whoa! When I think 30" reflector, I immediately thing Dobsonian. That's got to be one heck of a GEM--an Orion Atlas no doubt?


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BluewaterObserva
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Re: What's the largest size amateur dob available? new [Re: robininni]
      #5926627 - 06/17/13 11:38 PM

I believe it is one of the largest aperture scopes, GEM mounted, still in use in the world.

800lbs of counterweight on there by the way.

If your curious:
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/4111141/page...

Edited by BluewaterObserva (06/17/13 11:41 PM)


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Bill Weir
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Reged: 06/01/04

Loc: Metchosin (Victoria), Canada
Re: What's the largest size amateur dob available? new [Re: BluewaterObserva]
      #5926752 - 06/18/13 01:39 AM Attachment (47 downloads)

This is the f/5 25" that I was out visiting tonight at the school observatory. I was supposed to be showing a visiting school group around the observatory but unfortunately the weather didn't cooperate. That metal tube is 9' long. Counter weights are in the 800lb range also.

Bill


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Bill Weir
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Reged: 06/01/04

Loc: Metchosin (Victoria), Canada
Re: What's the largest size amateur dob available? new [Re: Bill Weir]
      #5926756 - 06/18/13 01:42 AM Attachment (44 downloads)

This is what it looked like in the beginning before it was painted and Jack Newton was still dragging it around on a trailer to dark sites. This was before he donated it to the school.

Bill


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kfrederick
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Reged: 02/01/08

Re: What's the largest size amateur dob available? new [Re: Bill Weir]
      #5926876 - 06/18/13 06:28 AM

A 40 inch f3 the eyepiece is under 100 inches above the primary .The diameter is not the pain it is the length of the OTA A 39.4 inch supper max blank is not bad price .

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LivingNDixie
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Re: What's the largest size amateur dob available? new [Re: kfrederick]
      #5927394 - 06/18/13 12:05 PM

There are four 36in Obsessions in existance. One is owned my Larry Mitchell in Texas. One is owned by a guy in Birmingham Alabama. I don't know where the other two are. These scopes are massive.

Edited by LivingNDixie (06/18/13 12:07 PM)


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Pinbout
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Reged: 02/22/10

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Re: What's the largest size amateur dob available? new [Re: LivingNDixie]
      #5928354 - 06/18/13 10:19 PM

What about tom clarks 42? I'd like to look thru that scope since lockwood worked the mirror.

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FJA
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Reged: 11/17/04

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Re: What's the largest size amateur dob available? new [Re: LivingNDixie]
      #5965235 - 07/11/13 07:04 AM

Quote:

There are four 36in Obsessions in existance. One is owned my Larry Mitchell in Texas. One is owned by a guy in Birmingham Alabama. I don't know where the other two are. These scopes are massive.




I'm fairly (though not 100%) certain that a guy here in the UK has got one.


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George N
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Reged: 05/19/06

Loc: Binghamton & Indian Lake NY
Re: What's the largest size amateur dob available? new [Re: LivingNDixie]
      #5965610 - 07/11/13 12:21 PM

Quote:

There are four 36in Obsessions in existance. One is owned my Larry Mitchell in Texas. One is owned by a guy in Birmingham Alabama. I don't know where the other two are. These scopes are massive.




One Obsession 36 is (was?) owned by a guy in New Hampshire. He brought it to Stellafane 2 or 3 years, where I had a chance to look thru it and talk to the owner. Some other folks who know him have told me that he now has it in an observatory at his home.

I kept thinking of this scope as "Dobasaurus Rex"! It was huge. However, it was possible for one person to set up. Like the Obsession 30's, it is on wheels that are rotated out of the way when observing. It also cranks down after the truss poles are in place to hang the UTA on while standing on the ground. The owner had added a finder scope on an additional pole so that it could be used while standing on the ground. The 36 was transported in a trailer with a ramp backdoor, so to get it out, you just push it down the ramp. To get it back in the trailer, there was a small electric winch at the front of the trailer (powered by the tow vehicle's battery). Attach the cable to the scope - pull it up the ramp.

The owner told me that he was thinking of going back to a 20-inch, but he never did. He also said that owning a scope this size was "a lifestyle choice, like getting married or joining a monastery."

I've seen a number of other 28 to 32 inch Dobs that I consider designed to be easier to set up than the Obsession 36..... but that is a relatively old scope that now seems 'slow' at F/5.


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derangedhermit
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Loc: USA
Re: What's the largest size amateur dob available? new [Re: JayinUT]
      #5965643 - 07/11/13 12:44 PM

Quote:

Anyway, Mike Clements is building and is almost done with his 70 inch reflector which is out at Steve Dobbs home/land. Here is a link to a post in February on that from my blog.



If my eyes do not deceive me, that's a 9-"point" (disc) cell.


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dan_h
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Reged: 12/10/07

Re: What's the largest size amateur dob available? new [Re: kfrederick]
      #5965672 - 07/11/13 01:09 PM

Quote:

A 40 inch f3 the eyepiece is under 100 inches above the primary .The diameter is not the pain it is the length of the OTA A 39.4 inch supper max blank is not bad price .




I believe Kim Colter has a 40" Dob in a permanent home in Missouri. I don't know the f ratio.

dan


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Achernar
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Loc: Mobile, Alabama, USA
Re: What's the largest size amateur dob available? new [Re: LivingNDixie]
      #5965676 - 07/11/13 01:11 PM

Massive does not begin to describe any 36-inch Dob, not when you see the eyepiece 15 feet above the ground. I've only seen one Dob in person that was that big. It was at the 2006 Okie-Tex starparty and to say the least it stood out among a forest of large Dobs that were on the site. Seeing how tall of a ladder was needed to reach the eyepiece, I opted not look through it. I work off of ladders and at heights for a living, I do not like climbing in the dark, not after falling off a ladder, not once but twice. In both case I was very lucky that I didn't get seriously hurt, or worse. I have heard of folks falling off a ladders while peering through big Dobs too.

Taras


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turtle86
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Re: What's the largest size amateur dob available? new [Re: Pinbout]
      #5965696 - 07/11/13 01:26 PM

Quote:

What about tom clarks 42? I'd like to look thru that scope since lockwood worked the mirror.




It had great views even before Lockwood worked on the mirror. On one cold memorable night Thor's Helmet looked almost three dimensional with near photographic detail.


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TechPan6415
sage
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Reged: 07/29/12

Loc: Aspen, Co
Re: What's the largest size amateur dob available? new [Re: JayinUT]
      #5984581 - 07/22/13 02:44 PM

Quote:

Anyway, Mike Clements is building and is almost done with his 70 inch reflector which is out at Steve Dobbs home/land. Here is a link to a post in February on that from my blog.




That....is....
insane!

The largest scope I ever looked through was a 36" Coulter Optical monster at Riverside in the early 90's. I saw color in M8 and it was pretty memorable. I figure until I get a permanent home I am good with my 16", a 24"-30" might speak to me more clearly if I have an observatory to put it in.

But 70"...wow, I could not imagine what those views would be like.


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Gord
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Loc: Toronto, ON, Canada
Re: What's the largest size amateur dob available? new [Re: TechPan6415]
      #5984649 - 07/22/13 03:31 PM

I will also mention Normand Fullum. When I spoke to him in the late spring (at the AstroCATS show), I think he said the biggest one he had done was 50 or 60". Pretty big for a private user!

But in the 30-40" range, my understanding is that he has done a number of them.

Also of great interest were the new cellular mirror blanks he was just getting. These are not the fused blanks you can see on his site, but actual cellular ones like Dream offers. The 12.5" was only 7 lbs!!! The biggest he had of these though was (only) 20".

The wheels have been turning ever since!

Clear skies,


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John Kuhl
sage


Reged: 11/10/05

Loc: SoCal
Re: What's the largest size amateur dob available? new [Re: Gord]
      #5984834 - 07/22/13 05:30 PM


I would think if you had enough money you could get as big of a scope as you want. If I ever hit a $100 million on the lotto I'd buy a 100 incher.

Best, John


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northernontario
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Reged: 07/01/09

Loc: Porcupine, Ontario Canada
Re: What's the largest size amateur dob available? new [Re: plyscope]
      #5985012 - 07/22/13 07:40 PM

Quote:

web page Normand Fullum telescopes




I had the pleasure of meeting him this year at the Oakville gathering.

He had a 36 inch mirror with him. Uncoated but ready to go.

He also had some of his hand crafted wooden scopes with him.

Incredible workmanship.

He stated that he would have a 36 inch at Starfest in August. There will be a few of our very own members there as well giving presentations.

I hope I can get out to this event, I can afford a trip there more than I can afford a 36 inch telescope.



jake


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FJA
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Loc: 50.65° N, 1.15° W
Re: What's the largest size amateur dob available? new [Re: John Kuhl]
      #5985017 - 07/22/13 07:45 PM

Quote:


I would think if you had enough money you could get as big of a scope as you want. If I ever hit a $100 million on the lotto I'd buy a 100 incher.

Best, John




I'd do something like that. That and move to the SW USA or the Australian outback where the air is dry and the skies clear...no point spending that kind of money on a scope living where I live. A handful of clear nights each month isn't so bad with an 18" but anything colossal would require good skies.

Btw the guy in the UK I thought had one of the Obsession 36" scopes actually has a 30".


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amicus sidera
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Re: What's the largest size amateur dob available? new [Re: TechPan6415]
      #5986632 - 07/23/13 07:08 PM

Quote:

But 70"...wow, I could not imagine what those views would be like.




I can.

Extremely limited field and, for the most part, seeing that turns all that light into pudding.

Pickering had it right all along.

Fred


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hbanich
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Re: What's the largest size amateur dob available? new [Re: amicus sidera]
      #5987264 - 07/24/13 01:37 AM

Not necessarily. I've observed with 48 and 90 inch scopes and they both produced wonderfully sharp views when the seeing settled down. When the seeing boiled up the views were still mesmerizing so I think optical quality will be the main determining factor in how well the 70 inch will perform. The mechanics of the scope are nearly as important, and I'm sure we'll start to hear more once the 70 inch begins its observing career.

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amicus sidera
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Re: What's the largest size amateur dob available? new [Re: hbanich]
      #5987549 - 07/24/13 09:22 AM

Very true, Howard; during times of excellent seeing the views would be fantastic. I'd think that the owner of such an instrument would of necessity be quite limited as regards siting the instrument; most of the interior U.S., save for the desert Southwest at altitude, would be out of bounds, due to the lack of sub-arc-second seeing on a regular basis.

Fred


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davidpitre
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Re: What's the largest size amateur dob available? new [Re: amicus sidera]
      #5988544 - 07/24/13 09:42 PM

I think those who dismiss these very large scopes have likely not used them. I have used the McDonald 82" with both good and not so good seeing. Regardless, the views were staggering. Such a scope does not at all require sub arc-second seeing. True, with poor seeing, it's not worth the effort, but then neither is my 4" in my book.

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omahaastro
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Re: What's the largest size amateur dob available? new [Re: davidpitre]
      #5988603 - 07/24/13 10:15 PM

I'm not sure I'd want to go much narrower than the 2/3rd degree max FOV I've got with my big gun today though. I still enjoy looking at some more expansive objcts. These mega scopes are sporting some mini fields of view.

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CounterWeight
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Reged: 10/05/08

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Re: What's the largest size amateur dob available? new [Re: omahaastro]
      #5989322 - 07/25/13 11:00 AM

Would love to see an update on that whopper!

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