Heat and SCT collimation

Last night, after a month hiatus, I finally got out to my observatory to
peek at things and found my C-11 was severely out of collimation.
This the first Texas summer that the scope has been enclosed in the
observatory. I suspect the heat may have had something to do with the
de-collimation, but of course, this is only a guess.
Anyone had similar experience with a SCT in a hot environment?

Robert B.

My 10" SCT retains it's collimation quite well here in the low desert of
Arizona. But it lives on a JMI wheeley bar with 5" wheels (very smooth
mobility inside and out), so it stays inside except when I'm going to be
observing.

There certainly are plenty of dissimilar materials in your C-11 for it to
work it's way out of collimation over time if the low-high-low-high-low
temperature differentials are sufficiently disparate, like they can be
here. I chose long ago to maintain my scopes in a climate controlled
environment, rather than outside, though there can certainly be
significant advantages in an observatory environment as well, and an
observatory CAN be climate controlled...

"Robert Burns" wrote in message
...
Last night, after a month hiatus, I finally got out to my observatory to
peek at things and found my C-11 was severely out of collimation.
This the first Texas summer that the scope has been enclosed in the
observatory. I suspect the heat may have had something to do with the
de-collimation, but of course, this is only a guess.
Anyone had similar experience with a SCT in a hot environment?

Robert B.

On Tue, 15 Jul 2003 12:46:08 -0500, "Robert Burns" wrote:

Last night, after a month hiatus, I finally got out to my observatory to
peek at things and found my C-11 was severely out of collimation.
This the first Texas summer that the scope has been enclosed in the
observatory. I suspect the heat may have had something to do with the
de-collimation, but of course, this is only a guess.
Anyone had similar experience with a SCT in a hot environment?

Not as hot as yours, but my 12" LX200 has now had two years of cycling over a
range from about -10F to +110F, with daily deltas as large as 40-50F. I haven't
collimated it since I installed it on its pier, and there has been no apparent
change.

_________________________________________________

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

Anyone had similar experience with a SCT in a hot environment?


Hi Robert:

No...this is a new one on me. It obviously gets _very_ hot down here on the
Gulf Coast and I've never heard of this. When you finished collimating last
time, the screws were all decently snug, weren't they?

Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto http://members.aol.com/RMOLLISE/index.html

"Robert Burns" wrote in message ...
Last night, after a month hiatus, I finally got out to my observatory to
peek at things and found my C-11 was severely out of collimation.
This the first Texas summer that the scope has been enclosed in the
observatory. I suspect the heat may have had something to do with the
de-collimation, but of course, this is only a guess.
Anyone had similar experience with a SCT in a hot environment?

Robert B.

Mine doesn't, but I keep it in a case that tends to average out the
temperatures.

What orrentation do you store you scope?

I store mine pointing towards zenith, in an out of focus position.

I could see a scope stored in a horizontal position might put a
unequal strain top-to-bottom on the sliding bearings one the
primary to central shaft.

Mitch