Dew on the mirror?

[Noreik]

Hello all,

I'm very happy with my 10" dob but I have noticed that when looking at Jupiter there is the kind of blooming of the light that you get when looking at headlights through a rainy windscreen and I wondered if it was dew on some part of the telescope and if it is, how I get rid of it.  I keep the telescope fully set up on its mount in my garage with an old settee throw over the top of it - might that be causing the issue if that's what it is?

Thanks for any advice,

Noreik

[DevonSkies]

15 minutes ago, Noreik said:

Hello all,

I'm very happy with my 10" dob but I have noticed that when looking at Jupiter there is the kind of blooming of the light that you get when looking at headlights through a rainy windscreen and I wondered if it was dew on some part of the telescope and if it is, how I get rid of it.  I keep the telescope fully set up on its mount in my garage with an old settee throw over the top of it - might that be causing the issue if that's what it is?

Thanks for any advice,

Noreik

Have you seen this on several occasions, or just the once? It could simply be some high cloud causing light scatter.

[brantuk]

Perhaps your old settee throw doesn't provide enough ventilation to keep the mirrors clear. Most scope covers are breathe'able and allow air to circulate. A dew shield is a great solution - also consider a secondary mirror dew heater. Hth

[RikM]

I agree with the above advice. A dew shield is a great addition to SkyWatcher Dobs and I always use one with my 250px.

[Noreik]

Thanks for advice.

Now have dew shield ordered.

What would people advise to get rid of existing dew? Bringing scope indoors or just blowing a hairdryer down the tube?