is it ok to use a reflector telescope....

[star_raider]

... on cold nights without any specail stuff? winn the mirrors frost or anything and is frost on them bad for it?

 

[tfwthom]

On the whole reflectors don't have a problem with dew. You do need to let them equalize to the outside temp before you observe. <br /><br />Truss type scopes sometimes have a problem with frost but mostly the shroud takes care of that.<br /><br />If frost develops on a mirror or corrector plate (SCT) it will not hurt anything if left to the open air to dry. Just kills your night of observing.<br /><br />There are ways to prevent dew/frost on SCTs or refractors but reflectors really don't have the problem. <div class="Discussion_UserSignature"> <font size="1" color="#3366ff">www.siriuslookers.org</font> </div>

 

[Saiph]

hmm, here's a question: Would heating it with a blow-dryer before bringing it in stop the condensation, without adversely affecting the mirror? This is after you're done observing for the night of course. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>

 

[wisefool]

I have owned several reflector scopes, and know about dozens of others among my friends. Bottom line: Unless it's swampy outside, condensation is not usually going to be a problem. It almost never is on the primary mirror, but it can be on the secondary mirror. In the last year I have only had problem with dew on my secondary one evening, and that was after the ground was saturated with a hurricane. The best way to avoid dew is to get above the moisture, if possible on a hill or mountain. By the way, any scope can dew over under the right conditions, and that includes SCTs and refractors.