Dew Management Advice Please

[Andy ES]

Hi 

I’m  just starting to use my new CPC925 and as I’ve read on SGL I’m expecting dew problems with this SCT. I just wanted to ask what would be the best procedure to follow to try and minimise this?

The scope will be stored in an attached garage which is quite cool to start with.

I also have a dew shield which is heated and I’ve got a desiccant cartridge on order.

 So please, what is the best way to pre cool it or warm it, then use it and bring it back inside and store it after.

Basically I’m not sure what temperature it should be at, what the cooling/heating times should be or when and how to remove dew when it forms during or after use.

One other question is where exactly should the dew shield be placed? Should the heated band be in line with the corrector plate? or a bit further back towards the eye piece end?

As always thanks in advance  for any advice you can give me.

 

[kirkster501]

You keeping it in the unheated garage is the best thing you can do other than have an observatory.  Even with an observatory, there can be a temperature delta between having the roof open and closed.  When I had my 14" SCT this was very apparent sometimes.  Such large scopes need to be outside otherwise they need multiple hours to cool down.

A dew heater or shield will help with the dew.

[Cosmic Geoff]

First, I have found that I need to use a dew shield with a Mak or SCT unless the humidity is low.  I have never bothered with a heater band and can only recall one night when despite the dew shield, the corrector plate dewed up aftter a while enough to interfere with observing.  Photos of SCTs in use will show you how to place the dew shield (basically extending forward from the front casting).

If you keep the outfit in a garage, by the time you 'fool around' for 20 mins or so setting it up it outdoors, it should be cool enough.

After use I take my telescopes indoors and let them dry out naturally, with round plastic dust covers in place.  Dew is pure water so it should all disappear without leaving a residue, and if the manufacturers were doing their job the finish should not take any harm.

[Andy ES]

Thanks for the advice

[dweller25]

A dew shield and wrapping the scope with reflectix will help.