Do you leave your fan on all night?

[Doc]

Now that my counterweight mod is finished I'm turning my attention to a fan for the base of my dob.

I'm intrigued by Dion's from Astronomy Shed's idea, it looks really cool so going to plan my fan around his design.

My question is:

1. Who uses a fan to cool their scope down?

2. If so is it turned off when the you start observing.

3. Or do you leave it on during your observing session.

The school of thought now is to leave it on all night at a low speed, apparently it removes all the turbulaence and inproves the view. It also stops your primary mirror from dewing up.

Whats your thoughts on this?

[BAZ]

I agree with Pat, I leave mine on low speed all night, it does prevent tube currents forming.

There is a marked difference if I turn it off, leave it a few minutes, look through the eyepiece and turn it on, the image just goes stable.

[Teslar]

Dion told me it was ok to leave mine running on the Quattro. It hasn't harmed any of his imaging so I expect it will be good with mine

[Brantuk]

I've never used one so far - but I've read a lot about them recently and it's really interesting (either that or I have no life lol). Here's a great link if you want to calculate the benefits to the nth degree. It answers all those questions like high or low, constant or periodic, blow or suck....etc. There's also good links at the bottom to other articles.

http://www.cruxis.com/scope/mirrorcooling.htm