Bushnell telescope

[Schorhr]

The mirror, or the lens in the eyepiece?

[bingevader]

I think he means the mirror.

cool down? how?

If you store your 'scope in doors then for optimum viewing it needs time to cool down to the temperature outside to avoid warm air currents.

It takes less time for a newtonian because it's open at one end (my 8" dob only takes 20-30mins but the etx90 which is enclosed can take up to an hour).

It doesn't mean you can't start viewing straight away, but you'll be surprised at the difference.

Cheers