TheSkySearchers

My corrector plate has been misting up on the inside in use! I keep the telescope in a Celestron case in the garage and put it away after a session so the dew gets zipped in with the OTA each time. I don't think it's doing it any good. Here's my secondary mirror today:


I've had the OTA indoors with the secondary removed to dry it out.

I wondered what others do to deal with the dew after a session?

Regards

Graeme

With a closed tube scope I always let the humidity equalize before putting the OTA in its case. I leave the visual back open and unoccupied and the tube horizontal (dust, etc.) falls down. I'll often leave it this way overnight.

I've treated my Intes MK66 this way for the 17 years I've had it and the optics are whistle clean. (The OTA exterior is scuffed but, hey....)

In between sessions you could use dessicant to keep humidity low inside the tube.
A 35mm film canister with holes in the barrel can be placed in a 1.25" adapter to seal the tube.
You can also use a stainless steel tea ball and place it inside the focuser drawtube.

notFritzArgelander wrote: ↑Sat Feb 20, 2021 9:11 pm With a closed tube scope I always let the humidity equalize before putting the OTA in its case. I leave the visual back open and unoccupied and the tube horizontal (dust, etc.) falls down. I'll often leave it this way overnight.

I've treated my Intes MK66 this way for the 17 years I've had it and the optics are whistle clean. (The OTA exterior is scuffed but, hey....)

Thanks nFA. Good strategy. Do you bring it in after the session or leave it out in the external temperature? I think that my problem with the flocking paint was caused by bringing it indoors after a particularly humid session but I didn't leave it open. Well it's been indoors with both ends open for four hours and the sky was clear earlier, but it's clouded over now so I'll have to wait to test it!

Lady Fraktor wrote: ↑Sat Feb 20, 2021 9:18 pm In between sessions you could use dessicant to keep humidity low inside the tube.
A 35mm film canister with holes in the barrel can be placed in a 1.25" adapter to seal the tube.
You can also use a stainless steel tea ball and place it inside the focuser drawtube.

I have a good sized dessicant bag somewhere. And I'm sure I can find an old film canister.

Thanks

Regards

Graeme

Graeme1858 wrote: ↑Sat Feb 20, 2021 9:45 pm

notFritzArgelander wrote: ↑Sat Feb 20, 2021 9:11 pm With a closed tube scope I always let the humidity equalize before putting the OTA in its case. I leave the visual back open and unoccupied and the tube horizontal (dust, etc.) falls down. I'll often leave it this way overnight.

I've treated my Intes MK66 this way for the 17 years I've had it and the optics are whistle clean. (The OTA exterior is scuffed but, hey....)

Thanks nFA. Good strategy. Do you bring it in after the session or leave it out in the external temperature? I think that my problem with the flocking paint was caused by bringing it indoors after a particularly humid session but I didn't leave it open. Well it's been indoors with both ends open for four hours and the sky was clear earlier, but it's clouded over now so I'll have to wait to test it!

Lady Fraktor wrote: ↑Sat Feb 20, 2021 9:18 pm In between sessions you could use dessicant to keep humidity low inside the tube.
A 35mm film canister with holes in the barrel can be placed in a 1.25" adapter to seal the tube.
You can also use a stainless steel tea ball and place it inside the focuser drawtube.

I have a good sized dessicant bag somewhere. And I'm sure I can find an old film canister.

Thanks

Regards

Graeme

I bring the OTA indoors to "room temperature" (20 C) immediately after the session so the drying can start promptly. Desiccant is ALWAYS a good idea.

I used to live near Seattle where humidity was often an issue. A student I was tutoring knew I "worked on scopes" and brought me her dad's Televue Genesis to ask if I could clean it. I saw a fine web of mildew in the airspace of the front doublet. I declined to work on it and told her to send it back to Televue. Seeing that real life horror caused me to be careful about moisture.

KathyNS has a different protocol than mine which differs sharply. It works for her as mine works for me.

I observe in a high humidity environment, which has averaged 95 percent humidity and a lot of nights at 100 percent for the last half year (thanks to La Nina). I leave my scopes and eyepieces indoors, horizontal, with all caps removed overnight. If the scope or mount is soaking, I'll wipe down with a cloth and use a hair dryer on low speed and heat to dry optics. I've been doing it this way for a couple decades with no mould or other issues for my reflectors and refractors and the last few years with my Mak.

I find that I need to take care in storing my kit in my garage. The humidity cycle in the closed garage, no matter what season, seems to be rather drastic.
Desiccant seems to do the trick in conjunction with equalizing the kit before closing it up in a case or other closed compartment.
High humidity summer environments in my garage without some air movement can be disastrous. In the summer I cover only with a cotton sheet and keep the garage door open a few inches and the window in the rear of the garage open a few inches as well.

blow the tube for a few mins an hair dryer ? maybe tape some desiccant capsules inside the tube ? ota heater ?

https://www.firstlightoptics.com/astron ... p-old.html

I also have a bag of desiccant in the focuser/drawtube.