Orion's answer on optics pinch in ED80

"CLT" not@thisaddress wrote in message ...
Sounds more like a cooldown problem. If the cell were too tight for cold
nights, you would have seen the same result on other cold nights.


Hmm, not sure what you mean. There were no "other cold nights" for the
problem to recur on. That is, no other cold nights where I didn't use
a heater tape. I only used it without dew heater (on a cold night) on
the one occasion.

However, if by "cooldown problem", you mean I hadn't let it equalise
with the outside temperature enough - then yes, you could be right. I
had been keeping it indoors on a tripod ready to just "grab n go". But
I'd also been using the scope for over an hour when I noticed the
(potential) problem. Surely that's enough cooldown time?

Next time it's really cold I'll leave the heater off and report back.
If the problem recurs, then it must be some kind of cell constriction.
If not, then your theory looks favourite...

Cheers
Beats