Cooldown Is Important But...

[Mr Q]

    ...why wait to observe! The instant you bring your newtonian out to start cooling down, you can use it while the scope cools, depending on what type of objects you select to observe.

   At the beginning of the cool down, seek out objects to observe that do not need fine details to be resolved, such as open clusters, nebulae (other than planetary), most galaxies - any objects where details are not important or observable.

   As time passes, you can start to observe objects that do need some detail work but if more cool down is needed, go back to the above objects and when it appears that some details can be seen, try now for some objects requiring minor detail resolution.

   Before you know it, the scope will be cooled down for detail work. Even if this takes an hour or more, you ARE observing from the time you started the cool down process. Later you can try for more detailed objects, such as edge on galaxies, planetary nebulae, planets, Moon, globular clusters, etc., when the scope finally cools down.

   So DON'T just set up your scope for cool down and then go back inside - use it WHILE it's cooling down - especially when clouds are threatening (as they seem always to do in the U.K.). The only exception to this observing method is when imaging is planed as the primary activity of the session, which needs a fully cooled down optical system.

   And as a plus to the "observe now" tactic, this can change the outcome of an otherwise "useless" night's observing (when the temperature continually drops and hinders a complete cool down state) into  productive and rewarding nights, whether out for an hour or several   Try this new observing tactic and report back with your results, successful or not

[ChrisLX200]

Or... as a simple DIY project fit a plate with some 12v computer fans below your primaray cell, this will cut the wait by 1/2 to 2/3 the time it usually takes - and you can still observe (if you have a long enough cable ). It also helps track rapidly falling temperatures better, and also helps to break up the boundary layer which can form on the mirror and tube surfaces.

ChrisH

[swamp thing]

Totally agree

As far as I'm concerned cool down time is observing time. No point in waiting about, simply plonk, observe immediately.

Although I must confess I do sometimes set up and then have a brew before I start.

[Mr Q]

   Good tip Chris. But like some others out there, I usually fall prey to any cords hanging from my scope. Where I do most of my observing, its so dark that I had to repaint my scope's OTA with a bright white color (originally a light turquoise color) just so I would'nt trip over it

   I guess I'm one of those "bare bones" type of observers - no "add-ons" used for me. I have learned to adapt to the observing site's conditions. Dew is my most common problem but I found a nice small hill (40 feet above the surrounding area in a forest) and this site remains fairly dry when just a few feet lower down the hill is fogged over.

   As for the primary boundary layer problem, my scope came with a ventilation opening around the tube just below the primary that solves this problem

[Naemeth]

I think it's more critical with Maks / SCTs, anything that's very slow. My incoming Mak has a minimum magnification of 80x, probably more than I'd want to use if it was warm.

[acey]

I actually don't think cool down is important, not with my dob at any rate (which I use exclusively for DSO viewing). Transparency, sky darkness and eye adaptation are important.

[Mr Q]

   Yes, closed OTAs can be a problem with cool down but since (I believe) the more popular newts are in use today due to purchase costs, I often read on astronomy sites that, especially in the U.K., where observers set their scopes out to cool down and after a short period of time, the clouds (or worse, rain starts) while the owners are inside waiting .

   Since my DS 10 has pretty good mirror quality, I do put it to use with close doubles or planetary observing when the sky conditions permit but more times than not, the observing sky is far from excellent. That's one of the points I wanted to point out to beginners - that cool down time is wasted observing time even though a cooled down scope performs much better.

[Kirscovitch]

I usually bring the scope out and get my initial alignment taken care of right away then head back in for the rest of the gear and when I get back out, usually wait about 10 min to let the eyes adjust a bit then start right away.

[LukeSkywatcher]

I personally am not a person who waits for my scopes to cool down before i start observing. As the night goes on, the scope cools and views of objects become clearer and better. I tend to start off observing "The Usual Suspects" and move on to DSO's as the night moves on and the scope cools.

[AlexB67]

IN the UK where humidity is frequently 80% or more  dew can become a problem too after a while, So yes, there is some good low power observing to be done when the scope is still cooling. On those very damp conditions  the way I see it is a trade off, better to view something for the extra time gained. A warm scope is better than scope with dew at the end   

Must admit though I never use anything  but low power during cool time, certainly no Jupiter viewing. Even in a 10 inch scope  I find the view is horrendous at 100+, but after 10 - 15 minutes it begins to improve drastically. I am surprised, ( I do not use a fan ) but those pyrex SW 10 inch mirrors settle very quickly, most of the  important settling down of the optics is done after 20 minutes or so I find. It will improve thereafter I notice, but much smaller margins.