Open tube SCTs

Hi all,

I was sitting around a few weeks ago with a buddy of mine and we got to
talking about different scope designs and I got to wondering if there
has ever been a truss rube SCT or Mak designes and or built. If so what
were the results?

I imagine it would cool down very fast, though dust on the optics could
be an issue.

If it hasn't been done why not? Is it a collimation issue? What about
cutting slots in the OTA to help speed cooldown.

Thanks

Craig

--
You have no right to protection against being offended.

Craig M. Bobchin wrote:
[...]
I imagine it would cool down very fast, though dust on
the optics could be an issue.

If it hasn't been done why not? Is it a collimation issue?

The Meade RCX400 has a gap between the edge of
the corrector and the inside wall of the front cell. This
promotes cooldown and also the ingress of dust and
bugs.

What about cutting slots in the OTA to help speed
cooldown.

Or "ventilate" the side of the OTA with a .357 Magnum.
:-)

wrote:
Craig M. Bobchin wrote:

[...]
I imagine it would cool down very fast, though dust on
the optics could be an issue.

If it hasn't been done why not? Is it a collimation issue?


The Meade RCX400 has a gap between the edge of
the corrector and the inside wall of the front cell. This
promotes cooldown and also the ingress of dust and
bugs.


What about cutting slots in the OTA to help speed
cooldown.


Or "ventilate" the side of the OTA with a .357 Magnum.
:-)

9mm will stabilize anything, except a Mak...... ;-)

Why not use a .454 Casull? that'll put a nice couple of vent holes in
the sucker.

In article .com,
says...
Craig M. Bobchin wrote:
[...]
I imagine it would cool down very fast, though dust on
the optics could be an issue.

If it hasn't been done why not? Is it a collimation issue?

The Meade RCX400 has a gap between the edge of
the corrector and the inside wall of the front cell. This
promotes cooldown and also the ingress of dust and
bugs.

What about cutting slots in the OTA to help speed
cooldown.

Or "ventilate" the side of the OTA with a .357 Magnum.
:-)



--
You have no right to protection against being offended.

For me, the closed tube on my C8 is one of it's good points. I don't
consider the cooldown time to be a big problem, and it stays CLEAN in
there.
Also, I find the inappropriate remarks concerning firearms to be
highly irresponsible. A .45 ACP with lightly loaded semiwadcutters
would do just fine if one did want to vent his telescope.
Marty

Marty wrote:
For me, the closed tube on my C8 is one of it's good points. I don't
consider the cooldown time to be a big problem, and it stays CLEAN in
there.
Also, I find the inappropriate remarks concerning firearms to be
highly irresponsible. A .45 ACP with lightly loaded semiwadcutters
would do just fine if one did want to vent his telescope.
Marty


I do tend to agree, however a 500 H&H round would tend to clean
up the "rough-edges." ;-)

jon

"Gobbletwo" wrote in message
...
Marty wrote:
For me, the closed tube on my C8 is one of it's good points. I don't
consider the cooldown time to be a big problem, and it stays CLEAN in
there.
Also, I find the inappropriate remarks concerning firearms to be
highly irresponsible. A .45 ACP with lightly loaded semiwadcutters
would do just fine if one did want to vent his telescope.
Marty


I do tend to agree, however a 500 H&H round would tend to clean
up the "rough-edges." ;-)

jon

Anyone have a howitzer?

Anyone have a howitzer?
------

I have a 6 inch light gas gun capable of launching several Kilograms at
several hundred meters per second. It is a laboratory instrument used
only for scientific work. I am not sure that pounding some sense into
Science.Astro.Amateur would be considered appropriate usage but it
might take something of the magnitude to get it back on track...

As far as SCT's with open frames, probably few and far between but I
think there are Schmitt Cameras that are open frame design.

jon

One reason you see SCTs from the 1970s with good coatings (still) is
the sealed tube. Even thought it's open at the eyepiece end, it
doesn't promote
the kind of dust and air circulation that a Newtonian does. A highly
filtered fan
(like the one on the Meade 7" Mak) is a good idea.

You need something with high velocity and full wadcutter configuration.
Sone of the old .460 Weatherby rounds with the faces milled flat.