Remove Dust Cover?

[Sunshine]

I was wondering, when leaving my Mak outside for a while to reach temperature, does it matter whether the dust cover is left on or off? . Will it cool/warm quicker with the cap off? 

[RT65CB-SWL]

I leave mine off... put on the dew-shield, remove the plug/end cap from the visual back... have a look through binoculars  or vape and wait!

Edited September 21, 2019 by Philip R

[PeterCPC]

Watch out for bird droppings 😣 if they are still about.

Peter

[ollypenrice]

Certainly take it off. Bird droppings only come from one direction so avoid that one! Warm air in the tube is going to want to escape upwards so an open visual back (covered to exclude intrusions!) in a tube pointing objective downwards seems logical to me...

Olly

Edited September 22, 2019 by ollypenrice

[Stub Mandrel]

I always take the cover off and leave the scope horizontal to cool.

[Carbon Brush]

Thinking here about thermal conductivity of the various materials in most Maks.

A metal tube, being a good thermal conductor, will transfer heat to the outside quickly. This means the air in the tube will cool quickly without the tube being left open.

Thick glass will hold a lot of heat. It has lower specific heat than aluminium. But is an awful conductor and can be in thick slabs. Well thick compared to the metal tube.
The front glass has one face to the outside to help cooling. But the mirror can only lose heat to the air in the tube.
I have not done actual trials, but my gut feeling is that a plastic (poor heat conductor) front lens cap will slow cooling.
If you can swap for a thin metal cap, that will help.

Could this be why, for example, the ETX90 (a budget scope) had an aluminium front cap?
In the numbers these were made, surely a mould plastic cap cost a lot less.

Just a thought, or two.

David.