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70 inch Dob sneak peek

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#1 Chuck Hards

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Posted 19 October 2013 - 07:49 AM

I'm headed over to take a look through it tonight. He built it in Steve's outbuilding at Nova Optical. I want to get there early enough to get some photos. This is a story by a local TV station, aired last night:

http://www.ksl.com/?...-record-by-b...
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#2 Sean Cunneen

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Posted 19 October 2013 - 08:20 AM

That is fantastic! Can you ask what he meant by the line "put the reflective coating on with a weed sprayer"??? That line made me gasp ;)

#3 Chuck Hards

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Posted 19 October 2013 - 08:23 AM

The mirror is too large for Steve's vacuum chamber, so they are silvering it, using a spray-on process. It works well, though must be renewed periodically due to oxidation.

#4 Chuck Hards

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Posted 19 October 2013 - 09:10 AM

29-inch secondary! Can't recall the size of the tertiary but it's relatively small. Welded steel structure. I'll get more details tonight.

#5 Jeff Morgan

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Posted 19 October 2013 - 09:49 AM

A tertiary mirror?!

He's losing light!!!!!!!!!!!!

:lol:

#6 Chuck Hards

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Posted 19 October 2013 - 10:09 AM

If configured as a standard Newt, the observer would be over 4 storey's high. By folding it, you "only" need to climb a 2-storey tall ladder. I'm going prepared for nose bleeds.

This will be interesting. I talked to him last week and he said at his lowest power, it took 3 fields to traverse M42. We are working on a lower power eyepiece together and he's making a large-diameter focuser to accomodate it. Something like 4". I'm taking him the focuser bearings tonight.

#7 Chuck Hards

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Posted 19 October 2013 - 02:01 PM

This is funny- at least 2 other people have posted links to the local news story in other forums, since I first posted this early this morning.

News is spreading! Mike's going to have lines forming soon.

"Build it, and they will come."

#8 MikeMcCaskey

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Posted 19 October 2013 - 02:09 PM

:bigshock: WOW!

#9 christheman200

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Posted 19 October 2013 - 03:22 PM

This really gave me a kick in the butt to get going on my 12" dob, if he can do that, I can build a 12" dob.

#10 Mirzam

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Posted 19 October 2013 - 03:24 PM

There is skepticism from one individual locally (here) that the mirror will produce an acceptable focus under gravity loading since it was originally designed to be used in zero G.

Curious what may have been done regarding mirror testing and support aspects, especially with Steve Dodds involved.

JimC

#11 Scott in NC

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Posted 19 October 2013 - 04:01 PM

Pretty cool! I'd love to get a look through that (but then, who wouldn't?). :cool:

#12 tim53

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Posted 19 October 2013 - 04:27 PM

I think I'd be tempted to put a camera at the Newt focus and save money by not buying a secondary or tertiary. Or ladder, for that matter!

I'd have to put a drive on it, though.

-Tim.

#13 Pinbout

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Posted 19 October 2013 - 05:06 PM

how far away do you have to be to KE test that mirror.

4 story to focus, 8 story to coc. 8x15' = 120' :foreheadslap:

#14 mikey cee

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Posted 19 October 2013 - 05:46 PM

That's all you dob owners would need. You'd ditch your 20"+ dobs in a heartbeat and become totally bummed out. :lol:Mike
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#15 DavidinFL

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Posted 19 October 2013 - 06:08 PM

That's incredible! He needs to publish a schedule of where he'll be so folks can come see it when he goes on tour.

#16 Pinbout

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Posted 19 October 2013 - 06:53 PM

Boy I see more of a jmi focuser then the scope... :question:

#17 northernontario

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Posted 19 October 2013 - 09:03 PM

I hope he brings that thing to Canada...

My backyard preferably..... :grin:

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#18 Pinbout

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Posted 19 October 2013 - 09:46 PM

Start singing the news...NY...NY.

#19 Chuck Hards

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Posted 19 October 2013 - 10:41 PM

I have just returned from Nova Optical, where the 70-inch scope is set up.

It's for real, folks. Steve, Mike, Charlie and I spent a couple of hours looking through high, thin cirrus but got some decent views of the core of M-31 as well as one of the best views of M-13 I've ever had, despite a bright, full moon and high haze.

Stars are perfectly round, there is no detectable astigmatism.

Even at nearly a ton total weight, it is still aimable by hand.

Wow, what a sight to behold.

Mike did say that he plans to take the scope on the road and hit as many major star-parties as his work schedule and budget will allow. He still has to pick up a trailer for the scope. It takes a full day to assemble once on-site.

The scope is going to remain operational through the winter at Nova Optical and Mike will operate it as his work schedule and the weather allow.

Steve seems to think that the silvered surfaces may only need to be renewed once a year. The current coating is a few months old and I could see no evidence of darkening (of course a visual inspection doesn't mean that reflectivity hasn't dropped, but it's encouraging).

I took a bunch of photos, including some close-ups of a few details and will post them tomorrow after I upload and process the ones that turned out.
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#20 miniventures

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Posted 20 October 2013 - 12:16 AM

Nothing short of incredible. Congrats to Mike for the foresight and perseverance!

#21 seryddwr

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Posted 20 October 2013 - 12:20 AM

I remember talking to Mike shortly after he got the mirror. I am still amazed, a 70" scope just boggles the mind!

#22 Mirzam

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Posted 20 October 2013 - 06:14 AM

Do you think one of the folks involved could do an article? A lot of ATM's would like to have more details I expect.

JimC

#23 Mark Harry

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Posted 20 October 2013 - 07:25 AM

Grab&Go
(a -WHOLE- new meaning!)
M.

#24 BigC

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Posted 20 October 2013 - 09:38 AM

I think "looking through the 70" scope" just got added to my list of "what I want to do"!

That is an amazing project .It shows that dreams can be achieved with hard work.

#25 Alan A.

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Posted 20 October 2013 - 11:20 AM

Thanks for sharing your observations through this scope. Its a landmark event in amateur astronomy, very exciting!






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