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

Recommendations for dew control for C11

  • Please log in to reply
7 replies to this topic

#1 CatSoup

CatSoup

    Lift Off

  • -----
  • topic starter
  • Posts: 2
  • Joined: 16 Jul 2019

Posted 12 October 2019 - 06:12 PM

I finally put together my EdgeHD 11 rig.  It has an (unheated) Celestron dew shield and Omegon heater strip run off a Pegasus Astro pocket powerbox and tonight I was dew'd out the whole night.  I live outside of Oslo and need to get sufficient heating to keep the front plate clear in the winter.  Obviously, one option is to replace the unheated dew shield with a heated one. Does anyone have any experience with cold temps? Would it be enough to get a heated dew shield and use it with the Omegon heater strip?  Are there any brands that are particularly good in cold temps?

 

Since importing these into Norway can add up quickly, I would prefer to nail this problem in one go, avoiding a more piecemeal approach.  I would appreciate any advice anyone could share.



#2 GalaxyPiper

GalaxyPiper

    Explorer 1

  • -----
  • Posts: 58
  • Joined: 20 May 2017
  • Loc: Sacramento, Ca.

Posted 12 October 2019 - 06:44 PM

Some people have rigged up low powered hair dryers and funneled up through the visual before using.

Some have modified the shell so the low heat scrubs the mirror to the side and on top of the front glass.

I'm not sure what temps you are trying to overcome, but you might have to try some variation on this theme.

Don't over heat, as this might do more damage than you can overcome, and also throw your scope out of calumniation drastically.

That's why I suggest low, low heat, and time.

 

Here is another thread on the subject.

 

https://www.cloudyni...-dryer-for-dew/

 

Here is another idea to change the ambient temperature inside the SCT. I'm sure these could be modified as low heaters. Again, just be careful. This could be used as a pre-warm up, then let the Dew heaters keep them warm.

Remember fridgid air has no moisture, but make sure it is dry air going in.

 

https://www.cloudyni...diy-sct-cooler/

 

Bryan


Edited by GalaxyPiper, 12 October 2019 - 08:41 PM.


#3 Migwan

Migwan

    Apollo

  • *****
  • Posts: 1425
  • Joined: 24 Jul 2017
  • Loc: Meeechigan

Posted 12 October 2019 - 07:19 PM

Hair dryer works, but for me, it was a PIA.   Where are you placing the dew strip?  I put mine directly behind the front cell holding the corrector. 

 

Before insulating the OTA with reflectix, I found it necessary to insulate the dew strip.  Back then, I used a strip of closed cell foam.  That worked very well, as does the reflectix that now covers the dew strip along with the whole tube.    Insulating over the dew shield will help some to.   Reflectix could be used for that too. 

 

jd


  • Bean614 and Dynan like this

#4 macdonjh

macdonjh

    Skylab

  • *****
  • Posts: 4353
  • Joined: 06 Mar 2006

Posted 12 October 2019 - 08:15 PM

I used two different dew heaters.  The first was an old-style Orion rubbery orange one.  It was 20W.  I then bought a Kendrick Firefly and installing it internally immediately behind the corrector.  I chose the Firefly because it was also 20W.  Both worked well as long as I turned them on at dark.



#5 gnowellsct

gnowellsct

    Hubble

  • *****
  • Posts: 15720
  • Joined: 24 Jun 2009

Posted 12 October 2019 - 09:00 PM

Here's a how-to on the installation of an internal dew heater which will greatly reduce power consumption and improve efficiency of your anti-dew technology.

 

https://docs.google....MFcL7O6dew/edit



#6 whizbang

whizbang

    Messenger

  • *****
  • Posts: 411
  • Joined: 18 Mar 2018
  • Loc: NE of Seattle, WA

Posted 12 October 2019 - 09:57 PM

I like to use an unheated dew shield AND a heat strip.

 

During short sessions or warm weather, I use just the dew shield.  In freezing or damp weather, both.

 

In winter I run the dew heat strip full time, full power.  The front of the tube near the corrector plate is the only area not damp at the end of a session.  Me, the tripod, the mount, and everything else gets soaked.



#7 gnowellsct

gnowellsct

    Hubble

  • *****
  • Posts: 15720
  • Joined: 24 Jun 2009

Posted 12 October 2019 - 11:03 PM

I've been getting requests for access to the document link I posted.  I find this strange because I set it for public access a long time ago.  Anyhow here is a link which google says is shareable.  Let me know if there are any problems.

 

Greg N



#8 CatSoup

CatSoup

    Lift Off

  • -----
  • topic starter
  • Posts: 2
  • Joined: 16 Jul 2019

Posted 13 October 2019 - 11:01 AM

I want to thank everyone for all the helpful replies.  I am going to order another heavy-duty strap from either Kendrick or R-Sky.  If that is insufficient, I will probably have to look into the more extreme option suggested by Greg (thank you for the link, it is very helpful).  I will also try to be a bit more pro-active; I didn't put on the dew cap and strap on until the corrector plate was already nearly dew'd up.

 

Thanks again, everyone.  Clear Skies!




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