Need a little help please. Mist inside my scope.

[TerryW]

Hi,

I have a Celectron 9.25 on an EQ6. The scope lives out in a state of perpetual north alignment because I am too lazy to do the alignment every time I use the scope. It is under a heavy duty scope cover.

Today I cleaned the objective lens and notice what looks like condensation on the internal main mirror. By way of experiment I wrapped my dew heater around the mirror end of the scope and found that the inside of the objective lens covers in condensation. I obviously have water inside the scope.

Does anyone have a remedy for this and is it something I should expect if I leave the scope out for a month?

Thanks in advance.

Terry

PS I also noticed that there are two dust spots on the inside of the objective lens that have a ring of condensation around them. I would love some advice as to whether I need to do anything about these. I really don't know if any of this is affecting the viewing except to say that my views of Jupiter have been very hazy.

[Aussie Observer]

I have the Nexstar11 and it has the same problem but it is never left outside. You will need to take it to a reputable telescope technician to have the corrector plate removed and cleaned and then replaced. Those "dust spots" are probably mould growing in the damp conditions. All this will definately degrade your image, so get it done asap.

[Ags]

Aussie is probably right, but you could bring the scope in to a dry environment and attach an eyepiece cooling fan to blow dry air into the scope. I have seen the cooling fans for sale on TS.

You could also put some dessicating salts into an old EP and convert it into a dessicator.

[TerryW]

Aussie is probably right, but you could bring the scope in to a dry environment and attach an eyepiece cooling fan to blow dry air into the scope. I have seen the cooling fans for sale on TS.

You could also put some dessicating salts into an old EP and convert it into a dessicator.

I brought the scope in and put some small dessicant bags in the opening where the diagonal attaches. I then used my Kendrick dew heater to warm the lot. Here's hoping . . . .

I'll post an update as I know there is great interest in keeping scopes outside. I rather doubt that the off-the-shelf Celestron C9.25 can be kept outside as it's construction is rather "open". Damp air can get in around the diagonal/eyepiece end and I am not sure that the sealing of the objective is any good. The plastic ring that secures the objective is sealed but whoever put it together made a real mess of it. They double sealed it in places which causes gaps in other areas. It can be re-built though which might be an option.

I look forward to seeing Jupiter without the haze ring around it . . .

[Ags]

By the way I doubt the spots dust or fungus are affecting your view, unless they are comparable in size to the central obstruction.

[TerryW]

Hi Ags,

The dust spots are tiny but they grow a condensation halo that is about 2mm across. I still doubt that they cause an issue at the moment. I'll wait and see how the drying out goes and take it from there.

Terry

[jgs001]

If it's fungus, then you probably want to get it out of there sharpish... the fungus will eat any coatings... if it's dust... then, of course, that's a different story altogether

[TerryW]

Hi John,

If the dust persists when th etube is dried out I'll start to panic and get the scope cleaned out. I am holding back at the moment to see how it responds to drying out.

I suppose I could dose it up with agent orange to kill the spores off.

Terry

[jgs001]

if the dust persists... it may be just dust... I don't know how, but if you can blow some air through (rocket blower maybe ??) and it shifts it, I guess it's probably bits of dust... I'm not sure how you could tell... sorry

[TerryW]

The whole thing looks easy to take apart. I'll study up on the scope's construction and see if it can be taken apart for cleaning.

I might as well wait for a year or two to make it worthwhile (as long as I am only dealing with dust).

Thanks for all the advice. It is much appreciated.

Terry