Speaking of mounts...

I stumbled across this very interesting page on Alt-Alt-Az mounts.
The idea is a dob-style mount that does away with eq platforms and field
derotation.

http://www.c2optical.com/mount.htm

I think it seems more complicated than it really is.

Regards,
Uncle Bob
37.9N 122.5W

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On 25 Aug 2004 01:17:50 GMT, Manuel Joseph Din
wrote:


SNIP


....Speaking of mounts...
A blonde, a brunette, and a redhead....
....ooops, sorry bad joke.


---Atreju---

Manuel Joseph Din wrote:


I stumbled across this very interesting page on Alt-Alt-Az mounts.
The idea is a dob-style mount that does away with eq platforms and field
derotation.

http://www.c2optical.com/mount.htm

I think it seems more complicated than it really is.

Regards,
Uncle Bob
37.9N 122.5W

__________________________________________________ _____________________________

Posted Via Uncensored-News.Com - Accounts Starting At $6.95 -
http://www.uncensored-news.com
The Worlds Uncensored News Source



Interesting... I've never seen a mount like this.

Have you seen the way JMI's NGT scopes are mounted? Here are
some pictures:

http://www.jimsmobile.com/ngt125_data.htm#Picture

Quite simple, but looks efficient. Looks to me like kind of
intergrated EQ platform.

- Alex

http://www.c2optical.com/mount.htm

I think it seems more complicated than it really is.

Looking through the eyepiece would be like playing twister

I stumbled across this very interesting page on Alt-Alt-Az mounts.
The idea is a dob-style mount that does away with eq platforms and field
derotation.

I wonder how long it would take to actually align the mount accurately enough
to achieve reasonable accuracy necessary to image.

Looks to me like the motion is really quite complex and that while in concept
it may be interesting, small alignment errors and mechanical imprecision would
make it very difficult to actually use in the real world.

jon

On Wed, 25 Aug 2004 09:29:23 -0700, Alexander Avtanski
wrote:

Have you seen the way JMI's NGT scopes are mounted? Here are
some pictures:

http://www.jimsmobile.com/ngt125_data.htm#Picture

Quite simple, but looks efficient. Looks to me like kind of
intergrated EQ platform.

It is a simple split ring equatorial. This is a common equatorial design for
many large professional telescopes (such as the Hale). Now, of course, most
large telescopes are altaz. The alt-alt-az design is clever, but IMO a better
design for most applications is alt-az with a field derotator. The same degree
of control is required for either design, but in the latter case one of the
elements is small, doesn't carry much load, and isn't really subject to flexure.
The only real advantage I see to the alt-alt-az design is that you can piggyback
on the scope and have all the instruments guided.

_________________________________________________

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

Chris L Peterson wrote:

On Wed, 25 Aug 2004 09:29:23 -0700, Alexander Avtanski
wrote:


Have you seen the way JMI's NGT scopes are mounted? Here are
some pictures:

http://www.jimsmobile.com/ngt125_data.htm#Picture

Quite simple, but looks efficient. Looks to me like kind of
intergrated EQ platform.

It is a simple split ring equatorial. This is a common equatorial design for
many large professional telescopes (such as the Hale). Now, of course, most
large telescopes are altaz. The alt-alt-az design is clever, but IMO a better
design for most applications is alt-az with a field derotator. The same degree
of control is required for either design, but in the latter case one of the
elements is small, doesn't carry much load, and isn't really subject to flexure.
The only real advantage I see to the alt-alt-az design is that you can piggyback
on the scope and have all the instruments guided.

_________________________________________________

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

I see it now, when you said it [that is is the same mount
mechanically]. Just the proportions are so different from
the Hale, where the ring dominates the structure, that I
didn't recognize the mount.

- Alex

(Jon Isaacs) wrote in message ...

I wonder how long it would take to actually align the mount accurately enough
to achieve reasonable accuracy necessary to image.

Looks to me like the motion is really quite complex and that while in concept
it may be interesting, small alignment errors and mechanical imprecision would
make it very difficult to actually use in the real world.

jon

Making accurate split rings may be more difficult than actually using them.

Chris.B

(Jon Isaacs) wrote in message ...
I stumbled across this very interesting page on Alt-Alt-Az mounts.
The idea is a dob-style mount that does away with eq platforms and field
derotation.

I wonder how long it would take to actually align the mount accurately enough
to achieve reasonable accuracy necessary to image.

Looks to me like the motion is really quite complex and that while in concept
it may be interesting, small alignment errors and mechanical imprecision would
make it very difficult to actually use in the real world.

Why is that? You've been around Dobs too long?

In the real world, mass-produced and inexpensive stuff with precision greater
than 10 arcseconds is readily and commonly available.

As just one for-instance (a supplier from whom I've equipped a good portion of
my home machine shop):

http://www.grizzly.com/catalog/2004/475.cfm?

referencing the rotary table(s). Sub-arcsecond accuracy is also readily
available (just not at a price I'm willing to pay :-) and commonly found which
is why I've no respect for slipshod astro junk from the likes of, say, Synta.

If you haven't visited a modern machine shop in the past several decades you'd
be astounded at what can be easily and inexpensively performed today. There is
absolutely NO reason for mechanical slop in any astro gear we buy except for
sheer laziness and/or incompetence and/or a "who cares?" attitude.

If you haven't visited a modern machine shop in the past several decades
you'd
be astounded at what can be easily and inexpensively performed today.

Actually I visit a top notch machine shop every day and I am on an advisory
committee for said machine shop.

There is
absolutely NO reason for mechanical slop in any astro gear we buy except for
sheer laziness and/or incompetence and/or a "who cares?" attitude.

Roland seems quite happy with 2 or so arc-seconds of PE. My calculation says
that 1 arc-second on an 8 inch diameter is right at 0.5 microns, or right at
one wave length of green light... I might be wrong but I don't think it all
that easy...

But my main concern is the accuracy with which one can align the scope to the
necessary stars. Just atmospheric refraction might be enough to foul things
up. With 3 variables, small errors would seem to multiply. Maybe with
multiple guide stars, one could more easily sort things out.

jon