cool down ?

[rory]

clear sky at the mo, put the dob out to cool for half hour or so.

question... front cover on or off to cool ?

sorry , theres going to be a few dumb questions from yours truly over the coming weeks.

[LukeSkywatcher]

Take the cover off but point the scope horizontally just incase it decied to start spitting down a bit of rain. 30 mins should be enough for an 8" scope but the longer the better. The expected rain clouds are moving in here from the SW.

[Mike73]

I take mine off and tilt it so it just off horizontal.

[rory]

Righto cheers chaps.

[LukeSkywatcher]

I take mine off and tilt it so it just off horizontal.

yeah just below horizontal is better. That rain stuff can come in from all directions except for upwards.

[umadog]

I leave mine pointing upwards when cooling. It will cool faster if the mirror can radiate heat into the sky. It's unnerving at first but remember that stuff can fall down the tube just as readily when you there as when you're not.

Often, however, I just start observing right away but leave high-power stuff until after it's cooled.

[LukeSkywatcher]

Warm air rises................cold air falls. So technically if your scope is a reflector then you should point it upwards to cool so the warm air escapes. So slightly uypwards of horizontal. I said downwards of horizontal so rain if any drops are around dont get on the primary.

[rory]

ok, next dumb question. long /short tube collimators ? which is suited to my telescope .

[cs1cjc]

With an 8", you may be able to start viewing straight away but I would be surprised if the scope is fully cooled for good high power, planetary viewing in less than an hour, particularly if the temperature outside is falling. However different scopes will behave differently and others may have better experience. A fan will help.