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Cool down and dew shield question

Started by ianfromoz , Apr 14 2014 01:41 AM
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5 replies to this topic

#1 ianfromoz

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Posted 14 April 2014 - 01:41 AM

I want to be sure that my 6 inch SCT has cooled down before use, i am thinking that 1 1/2 hours is enought time, can you please give me your opinions on this.
Also i have been told that you leave the dew shield off when cooling the scope down before use, but as dew can be an issue ( usually very high humidity ) will the tube still cool down if i were to put the dew shield on after an hour?
If you have a SE6 and live in a humid climate your comments will be appreciated...........come to think of it any comment will be appreciated.
:smirk:

#2 Tel

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Posted 14 April 2014 - 02:16 AM

Hi Ian,

I should have thought that 1.5 hours were more than enough to cool a 6SE, having moved one from a warm living room to a snow covered outdoors !

But seriously, don't become preoccupied with any hard and fast figures. Take the 'scope outside and before almost any time at all, you should be able to start observing with a 25mm EP. It's only when you come to step up the magnification, (i.e. use a shorter focal length EP) , that you will notice any effects caused by a temperature imbalance between 'scope and environment.

If therefore the image you see is poor, then just revert to a longer focal length EP until the temperatures reach equilibrium.

As to whether the dew shield should be left off or kept on, I've no opinion on this. What I would suggest is that with you living in a climate which seems very prone to producing dew on your 'scope, you probably have no alternative but to invest in some "dew busting" system and/or use a hair dryer carefully applied to affected components in order to disperse it.

Best regards,
Tel

#3 ianfromoz

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Posted 14 April 2014 - 03:49 AM

Thanks for your comments Tel, from what you say 1 1/2 hours should be plenty of time.
I reckon then that putting my dew shield on after an hour will be fine.
Starting to get colder here now, will need to put some socks on at night soon, seriously :-) With cooler nights i think the humidity will go lower which will be great.
Having plenty of rain at the moment, no doubt related to the ex cyclone up north.

Regards,
ian

#4 Midnight Dan

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Posted 14 April 2014 - 06:25 AM

Hi Ian:

The scope will cool a bit more slowly with the cover on, but I'd still leave it on to avoid dew as long as possible. Remove the cover and put your dew shield on immediately before you start observing.

But I agree with Tel. If you have humid conditions, you really need to start thinking about active dew heaters. I recommend the DewBuster controller, and Dew-Not heater straps.

-Dan

#5 ianfromoz

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Posted 14 April 2014 - 07:21 AM

Thanks Dan,
Yes in time i think i will need to invest in a dew heater.

#6 coutleef

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Posted 14 April 2014 - 10:23 AM

removing the cover during cooldown is the recepee to get a lot of dew!!

i leave my scope out in a plastic box with cover on going from 22C down to -30C for two hours (8se). so in my short experience 1 hour is good for a 6 se under less severe temp changes.

dew heather are a must in your condition
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