Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Additional Eye piece for Discovery 8" f6 1200 focal length dob telescope

  • Please log in to reply
28 replies to this topic

#26 SeattleScott

SeattleScott

    James Webb Space Telescope

  • *****
  • Posts: 19,924
  • Joined: 14 Oct 2011

Posted 18 March 2025 - 11:43 AM

The condensation will cause droplets that will leave water spots on the mirror, which will slightly degrade performance. Especially if you get a lot of them. They can be cleaned off, but mirror cleaning is a hassle, and it tends to wash off some of the protective coatings even if you do it right. So basically it degrades performance, or if you clean the spots off, you restore performance but likely reduce the life of the mirror coating a little. Plus it is just a hassle to pull the mirror and clean it. And of course after you put the mirror back in, you have to collimate again.

#27 T1R2

T1R2

    Soyuz

  • -----
  • Posts: 3,992
  • Joined: 11 Jun 2013
  • Loc: Little Rock, Arkansas

Posted 18 March 2025 - 12:33 PM

Yeah, keep the scope tilted sideways so moisture doesn't build up, not pointed directly at the sky for long periods of time, and if there is a big temp delta from the house to outside like in the dead of summer or winter it will fog over almost immediately, but there are things you can do like keep it in a room with a window that can be opened for about an HR or so before you go out to to equalize that temp delta. 



#28 todnik

todnik

    Vostok 1

  • -----
  • topic starter
  • Posts: 110
  • Joined: 04 Jan 2025
  • Loc: Mayer Minnesota

Posted 18 March 2025 - 04:12 PM

The condensation will cause droplets that will leave water spots on the mirror, which will slightly degrade performance. Especially if you get a lot of them. They can be cleaned off, but mirror cleaning is a hassle, and it tends to wash off some of the protective coatings even if you do it right. So basically it degrades performance, or if you clean the spots off, you restore performance but likely reduce the life of the mirror coating a little. Plus it is just a hassle to pull the mirror and clean it. And of course after you put the mirror back in, you have to collimate again.

This almost like watching children or baby sitting. Kind of full time work!



#29 todnik

todnik

    Vostok 1

  • -----
  • topic starter
  • Posts: 110
  • Joined: 04 Jan 2025
  • Loc: Mayer Minnesota

Posted 18 March 2025 - 04:13 PM

Yeah, keep the scope tilted sideways so moisture doesn't build up, not pointed directly at the sky for long periods of time, and if there is a big temp delta from the house to outside like in the dead of summer or winter it will fog over almost immediately, but there are things you can do like keep it in a room with a window that can be opened for about an HR or so before you go out to to equalize that temp delta. 

Thats good to know. Now if I can remember it.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics