Orion's Monster Dobs

Anyone ready to shell out $123K for a 50" Dob?

--
Tom Royer
If you're not free to fail, you're not free. -- Gene Burns

On Jan 5, 5:37*pm, "tcroyer" wrote:
Anyone ready to shell out $123K for a 50" Dob?

I see they have a 36" Dob for $55,600; while I'm not even in that
market, I suppose they might sell a few of those to some astronomy
clubs.

John Savard

UM where is a link to a page?


"tcroyer" wrote in message
...
Anyone ready to shell out $123K for a 50" Dob?

--
Tom Royer
If you're not free to fail, you're not free. -- Gene Burns

"Mark F." wrote in -
september.org:

UM where is a link to a page?



http://www.telescope.com/control/dob...ian-telescopes

"tcroyer" wrote in message
...
Anyone ready to shell out $123K for a 50" Dob?

--
Tom Royer
If you're not free to fail, you're not free. -- Gene Burns

I'll take 10.



"VicXnews" wrote in message
...
"Mark F." wrote in -
september.org:

UM where is a link to a page?



http://www.telescope.com/control/dob...ian-telescopes

"tcroyer" wrote in message
...
Anyone ready to shell out $123K for a 50" Dob?

--
Tom Royer
If you're not free to fail, you're not free. -- Gene Burns

On Jan 5, 7:37 pm, "tcroyer" wrote:
Anyone ready to shell out $123K for a 50" Dob?

How much for just the optics?

In article ,
Quadibloc wrote:
On Jan 5, 5:37=A0pm, "tcroyer" wrote:
Anyone ready to shell out $123K for a 50" Dob?

I see they have a 36" Dob for $55,600; while I'm not even in that
market, I suppose they might sell a few of those to some astronomy
clubs.

I'm surprised that the 40" is so much more expensive than the 36" (15%
more per square inch). To compare with other telescopes that cost
about as much as a new Porsche, the 36" Dob is about the same price as
an RCOS 20-inch OTA; the 40" about the same price as an RCOS 20-inch
OTA on a 3600GTO mount. I think I would expect an astronomy club to
prefer the astrophotography-capable machine, but it depends on the
interests of the donor.

I don't know how good these very large reflectors are at very fine
detail; part of me thinks that they'd be absolutely perfect
lucky-imaging tools - large image scales, loads of light, tracking not
necessarily a requirement if you're aligning the images anyway - and
that trying to collect $80k to buy one for Christopher Go would not
necessarily be a ludicrous idea, and part of me wonders if there are
any odd requirements on the mirror manufacture for good
high-resolution performance, and whether these would have been done
when making what's clearly being sold as an instrument for use with
the mark-one eyeball.

Tom

"Thomas Womack" wrote

I don't know how good these very large reflectors are at very fine
detail; part of me thinks that they'd be absolutely perfect
lucky-imaging tools -

My understanding is that any optic of this size is pretty much
seeing-limited. They most likely cannot provide any great detail unless the
seeing cooperates to maybe better than sub-arcsecond. Translation: I don't
know how important it is to make a great mirror for use where most people
live.

In article ,
Howard Lester wrote:
"Thomas Womack" wrote

I don't know how good these very large reflectors are at very fine
detail; part of me thinks that they'd be absolutely perfect
lucky-imaging tools -

My understanding is that any optic of this size is pretty much
seeing-limited. They most likely cannot provide any great detail unless the
seeing cooperates to maybe better than sub-arcsecond. Translation: I don't
know how important it is to make a great mirror for use where most people
live.

That was precisely why I mentioned lucky imaging, where the goal is to
take sixty images a second for ten minutes and pick the 1% of them
where the seeing happened to be steady.

The math suggests that you want a telescope diameter about six times
the size of the average blob of stable atmosphere, this size being
about six inches in 1-arcsecond seeing, to get enough images with
steady seeing; and the large aperture means you have lots of photons
in each 15-millisecond exposure.

On a 2.2-metre telescope, the Lucky Imaging team at Cambridge managed
to get 200mas-resolution images of a globular cluster core despite the
seeing being 1.5-arcsecond as normally measured.

http://www.eso.org/sci/publications/...r-no137-14.pdf

Tom

On Wed, 6 Jan 2010 12:20:16 -0500, "Howard Lester"
wrote:

My understanding is that any optic of this size is pretty much
seeing-limited. They most likely cannot provide any great detail unless the
seeing cooperates to maybe better than sub-arcsecond. Translation: I don't
know how important it is to make a great mirror for use where most people
live.

While Dobs are normally considered visual instruments, these are
available with tracking, so might also be used for imaging. In that
case, you always benefit from increased aperture, since exposure time is
determined almost entirely by aperture alone. With a large aperture, you
can either utilize shorter exposures or you can go deeper in the same
time.
_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com