Cover/dew shield

[RobertC]

Recently as the weather got colder at night my scope has been often getting covered in dew and have been meaning to get a dew shield, i have been looking at other peoples ways of getting around such so having spare underlay for wood flooring around i made my scope a sort of coating to keep it dew free and as protection for when transporting it.

Had a little also left so built my finder a dew shield that i can move to suit the weather conditions.

Not sure if anyone on here has done similar, if you have is there any modifications to such that may help ?

  

[jambouk]

Rob

Good work. DIY at its best, using materials lying around.

I've no idea if this is a good material as i'm not a DIYer; but looks ok.

As far as i'm aware you only need a dew shield over the opening of the scope; you don't need it over the body of the scope, but i am happy to stand corrected.

There is a formula someone once quoted about the dew shield should be 1.5-2 times the diameter of the scope in length, yours looks a bit short to me. Maybe i gave you duff information in a private message! Also, can you get it stiffer????? It looks like it is flopping a bit into the light path. You need some dew shield viagra

Great to post pics of the kit though. Good work.

James

[jambouk]

Thinking about it, covering the body of the scope may be bad as it may slow down the cool down time, and you'll end up with air turbulence inside the scope which could diffract the light.... I've only got a C at GCSE physics from 1989!

James

[RobertC]

I only have it covering the scope as the dew builds up on the outside of the scope and i hate bringing it into the house dripping wet. Both ends can be taken off so i will have to put them on the scope once it has cooled down, i take all my gear out in one go so all of it has cooled down by the time i have setup. Purely just for keeping the scope itself from getting dew build up put simply. 

The dew shield itself over the opening is pushed quite far back and not perfectly level, it's a snug fit just placed it on for the image

[jambouk]

OK. I'm glad it's not droopy all the time.

Just do be cautious about the covering on the body of the scope though. Again, I don't know much about this, but seeing as no one else has yet commented... I think even after the initial cool down period the scope continues to cool down, matching what the ambient temperature is doing (which is usually cooling down). Just be aware that this could contribute to apparent poor seeing for you.

If you are even using the dew shield when there is a breeze also be aware that the shield will likely add more surface area for the wind to catch on and to shake the scope and mount.

Next thing you need now is a secondary mirror heater

I hope the issues with the mount are resolved now.

James

[perfrej]

Covering the body is insulating material is about the best thing you can do as it reduces heat radiation which otherwise would lower the temperature of the equipment to closer to the dew-point. I covered my good old 250P in camping mat and the dew magically never materialized!

I refer you to my rant on the subject (post number 12): http://stargazerslounge.com/topic/119924-do-reflectors-need-dew-shields/

The mirrors will adapt to ambient anyway.

/per

[RobertC]

Well I'm glad my choice of DIY is the good then Need a nice clear night to check out my issues with the goto, my y mask and now if the dew prevention works .

[RobertC]

I can build a primary mirror heater just not sure about a secondary. I am defo going to look it up, I have plenty of materials to build such

If anyone has a link to such on here by chance i would gladly appreciate to see such.

-Rob

[RobertC]

I can build a primary mirror heater just not sure about a secondary. I am defo going to look it up, I have plenty of materials to build such

If anyone has a link to such on here by chance i would gladly appreciate to see such.

-Rob

[RobertC]

Oops it has double posted, iPhones for you.