Easy way to cool my reflector?

[Eucalyptus]

I'm getting some decent views of the planets with my new 6" dobsonian but I think it has some more potential in it if I can just cool it down some more. I don't know whether this is safe for my telescope or not, but I'm thinking of putting an ice pack mear it's mirror. I'm not willing to install a fan in it because it's going to cost quite a bit of money and it's also going to be quite difficult to do it. Will it hurt my telescope if I put an ice pack near the mirror(not inside it just outside it where the mirror is basically on the edge of the telescopes tube)

[Stu]

I would not recommend using an ice pack for this. You are trying to cool the mirror to ambient temperature, not below, so the best option is a fan, or just leaving the scope outside for longer before observing. Using ice risks causing dew on the mirror I would think.

[ronin]

Suspect that ice locally will cause more trouble then you may have, also it is not "cooling" as such it is getting the scope/mirror to the same ambient temperature as the outside world. You do not want thermal changes. If the ice pack cools it too much then you have to wait again for the mirror to warm back up to ambient.

Fan should be easy and inexpensive, people use the small ones that you buy for pushing air around a PC, they are a few dollars each and then a 12v supply of some variety. Not really sure how much they help. I suspect less then people hope. Will have a try and see if they spin with a 9v PP3 rechargeable if they do then you put fan in, wire to the battery and just let it run until drained (not long I suspect). That would equalise it quicker.

Simple solution is put the scope out first, point upwards and take the aperture cover off, then go get the rest of the bits and orgnise yourself. That is what I do with a goto. Set up tripod, level, aim North, go get the other bits. Just take the scope out first.

[Guest Tuomo]

And the difference is really huge, so basicly it is a must (cooled vs. Uncooled mirror)

[JG777]

In my experience a fan really does help. In recent outings with a new VX6 I tested it over various nights for cool down and compared to when I did not use it. In similar situations and as a rough estimate it reduced the cool down time by somewhere between 12 and 20 minutes. It may not sound much but every bit helps when clouds are approaching or time is short. Also if installing a fan you need to consider whether it will blow air up the tube or reverse it out. Both methods work in certain set ups. Fans need to be fitted properly and be the correct size and power to avoid causing vibrations to the primary mirror. Maybe start with leaving the scope out for longer or think about retro fitting a fan somehow. Ice is only really good for mixing with JD and coke.