Another OA Reflector

Orion would seem to be snaking in on Dan's market
but I doubt that they will do as nice a job and they will probably stay
small.

I disagree, I think they'll reach thousands of people who have never even heard
of Dan. I wonder how well they will sell.
rat
~( );

email: remove 'et' from .com(et) in above email address

Is there a web page where I can see "Dan's offerings?"


http://users.erols.com/dgmoptics/
rat
~( );

email: remove 'et' from .com(et) in above email address

"Jon Isaacs" wrote in message
...
The OTA is $649, and the focal length is 1240mm (f/13.6). The weight is
48.8 pounds, including the SkyView Pro equatorial ($999 for OTA and
single
axis drive, $1048 with dual axis drive).

Clear skies, Alan

Thanks for the information Alan.

At F13.6 this is a long scope and its only a 91mm scope. I don't see it
as a
big seller, what with their 100mm F9 APO only about $350 more and the
ED-80
considerably less.

And then Dan's offerings are something around F11 I think which would seem
to
be more attractive as well. Orion would seem to be snaking in on Dan's
market
but I doubt that they will do as nice a job and they will probably stay
small.
------------------

Looking at the photo of the Orion Scope it looks to me like they put the
secondary mirror on the other side of the OTA from the focuser. This
seems
wrong to me as it means the secondary has to be much bigger to achieve
reasonable illumination, one of the advantages of the OA Newt is that the
focuser can be quite close to the secondary. This seems to be the way the
DGM
scope is designed.


Dan has 2 designs. One with the mirror right under the focuser and his ATS
(across the scope design). That's the design that he made for my 6.5". The
mirror can be big as needed (although it wasn't that big in my scope)
because it won't be in the way :-)

Mike.

In article , CHASLX200
wrote:

Bet i could pump that 9" to 850x in good seeing...

Wimp! I bet I could do 852.3x, at least!

--
Joe Bergeron

http://www.joebergeron.com

In article , Alan French
wrote:

We just got a new Orion catalog, and they now offer a 91mm OA Newt.

Clear skies, Alan

I was wondering how long it would take for someone to mention this.

If this thing can beat their much cheaper 6" f/8 Newt in any meaningful
way they must be using some pretty crappy mirrors in them.

--
Joe Bergeron

http://www.joebergeron.com

I was getting the 6.5" OA over 500x in good seeing (the 2 times seeing ever
got that good). Most of the time around here it's under 250x no matter what
scope you use.

Mike.


"Joe Bergeron" wrote in message
ed...
In article , CHASLX200
wrote:

Bet i could pump that 9" to 850x in good seeing...

Wimp! I bet I could do 852.3x, at least!

--
Joe Bergeron

http://www.joebergeron.com

Dan has 2 designs. One with the mirror right under the focuser and his ATS
(across the scope design). That's the design that he made for my 6.5". The
mirror can be big as needed (although it wasn't that big in my scope)
because it won't be in the way :-)

Mike.

My concern is that by putting the diagonal across the OTA, defects in the
mirror are magnified. The closer the mirror is to the focal plane, the smaller
the spot size of a star on the mirror so the quality of the mirror is less
important.

I believe I have read this explanation by Roland as to why the quality of
Newtonian secondarys is quite critical where as refractor diagonals are less
so.

Also, big flats are more difficult to make than smaller ones...
Then I wonder what is the advantage of putting the secondary across from the
focuser instead of next to it?

jon
jon

I disagree, I think they'll reach thousands of people who have never even
heard
of Dan. I wonder how well they will sell.
rat

Hard to say how well they will sell.

They may be a real boone to Dan. Reaching those thousands, some of them are
bound to wonder if there are others available and if there are larger versions
available. Hopefully Dan will be ready for those folks.

jon

Mike Fitterman wrote:
DGM's 3.6 OA actually does quite well despite it's small size. It's
brightness and contrast was equal or better than in all cases to a TV101.

Hunh. I wasn't aware that the TV101's light throughput was less than
85 percent. Is that so?

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Mike Fitterman wrote:
too bad Orion stole the idea from Dan McShane. I know they bought one of
his scopes.

What? The idea of off-axis scopes is surely not new with Dan McShane.
I know you're a fan of his scopes, but I think this is carrying things
too far.

I suppose they "stole" Dobson's idea, too with their rocker box mounted
Newtonians. And when 2sky added a new database of a million stars, they
stole that idea from PleiadAtlas. Sheesh.

The optics also say "made in the USA". I wonder if they "borrowed" his
mirror maker as well.

Spit it out, Mike. What's got you bothered?

(BTW, anyone try out 2sky v3.0 yet? Any impressions?)

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt