dew

Hi all, i have been having problems with dew on the INSIDE of the corrector plate of my celestron cpc sct, i have a dew shield and heater strap which keeps the outside clear. Would changing eyepieces alot cause this? allowing cold air to enter. any tips and advice most welcome. thanks colin.

Hi,

I've had the exact same problem recently. It's just down to the humid weather I think. The humidity sensor at the scope doesn't even give me a sensible reading these days. Unless the sct was completely sealed air will move around when you change eyepieces, and you don't need a lot of moisture to get in to cause this it seems.

To fix the problem I left the scope with a dehumidifier running for a few hours.

Another solution I'm using at the moment is to put some silca pellets in the scope when not in use. You can get reusable ones on ebay that change colour when they are filled with moisture, and you can pop them in the oven to reactivate them. Put some small holes (smaller than the pellets!) in a 35mm film cannister, put the pellets in that and put the lid on. You can use that as your 'eyepiece' when the scope is not in use and it will draw any moisture from the scope.

Cheers,
~Al

This is an issue with my schmidt-newtonian. Like Al, I have a small dehumidifier that I put in a small room (back hall) with the telescope for a few hours. The dehumidifier was around £100 in Argos and clears the dew off quite quickly. As a bonus* you can use it to dry off clothes if you don't want to run the tumble-drier and keep the humidity in the house to a healthy level.






* May in fact be the reason why it was purchased.

thanks folks i'll give that a go.