I have a Sky-Watcher 114mm Newtonian and a Bresser 70/350 refractor. What’s the best position to put them in to cool them down properly?
Steve says “It is very important to ensure that your telescope is at ambient temperature to achieve the best views, as an imbalance of temperatures will result in disturbed air moving around in the optical tube, which will blur detail.
To add to the problem, air temperatures usually continue to drop throughout an observing session so to some extent you will be chasing the ambient temperature downwards.
Different telescope designs cool down at different rates, with Newtonian reflectors cooling faster than refractors.
The relatively large mass of the mirror in a reflector holds a lot of heat energy so blowing cool air over the mirror with a fan can help this to dissipate and some Newtonians have a cooling fan built in.
Warm air rises so to help it on its way, placing a Newtonian facing upwards and a refractor facing downwards – but with no diagonal or eyepiece in the focuser – is a good way of speeding up the cooling process.”
Email your astronomy queries to Steve at firstname.lastname@example.org and it could get answered in a future issue of BBC Sky at Night Magazine.