Split ring mount

I've been looking at equatorial mounts for large aperature telescopes
- especially newtonians - and it seems to me that the most stable are
split-ring mounts. But noone really makes them, so I have to wonder
about their usefulness. Are they stable enough for astrophotography?
How easy are they to build? And where can I find plans for doing so?

On Sun, 28 Aug 2005 17:20:55 -0700, Ernie Dunbar
wrote:

I've been looking at equatorial mounts for large aperature telescopes
- especially newtonians - and it seems to me that the most stable are
split-ring mounts. But noone really makes them, so I have to wonder
about their usefulness. Are they stable enough for astrophotography?
How easy are they to build? And where can I find plans for doing so?

JMI makes scope/mount systems using split rings. The split ring mount is
extremely stable, and is arguably the best equatorial design for imaging
with a large scope. However, like other fork mounts, it is hard to make
for a wide range of scopes, so it isn't common as an aftermarket item.

IMO the split ring mount is one of the easier to build equatorials, but
nevertheless, any large, stable mount is a major construction project.
I've never seen plans; if I were going to make one I'd design it from
scratch.

_________________________________________________

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

I thought JMI was still marketing one. Have they quit producing that line? I
wanted one for years but couldn't afford the one I wanted. I know it had some
problems with astrophotography early on, but they solved those problems.

--- Dave
--
----------------------------------------------------------------------
Pinprick holes in a colorless sky
Let inspired figures of light pass by
The Mighty Light of ten thousand suns
Challenges infinity, and is soon gone




"Ernie Dunbar" wrote in message
...
I've been looking at equatorial mounts for large aperature telescopes
- especially newtonians - and it seems to me that the most stable are
split-ring mounts. But noone really makes them, so I have to wonder
about their usefulness. Are they stable enough for astrophotography?
How easy are they to build? And where can I find plans for doing so?

On Sun, 28 Aug 2005 17:20:55 -0700, Ernie Dunbar
wrote:

I've been looking at equatorial mounts for large aperature telescopes
- especially newtonians - and it seems to me that the most stable are
split-ring mounts. But noone really makes them, so I have to wonder
about their usefulness. Are they stable enough for astrophotography?
How easy are they to build? And where can I find plans for doing so?

Ernie (and others),

I was interested in this too and was given this link (with plans and
other links) by a kind person at the skyquest-telescopes group so I
repay my debt of gratitude by passing it on - hope it is useful!
http://www.geocities.com/joe_pearson...ing_index.html

Jim

A well built split ring mount is among the most stable kinds of mounts
possible, and might be the most stable mounts that trackt he stars with
a single movement around a single axis.

The only real issue with SRM is that they are not as compact as a DOB
mount. A 20" DOB can be put into a 26" Square foot print, the smallest
SRM I know of takes about 33" round footprint for the same mirror
diameter. There are a lot of vehicles that can absorb a 26" square
footprint that cannot absorb a 33" round footprint. This relagates many
users to simply use a DOB with a computer controller for tracking.