Jump to content

Welcome to Stargazers Lounge
Register now to gain access to all of our features. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more. If you already have an account, login here - otherwise create an account for free today!
Photo

Making your own dew shield

- - - - -

  • Please log in to reply
10 replies to this topic

#1
beamer3.6m

beamer3.6m

    Sub Dwarf

  • Advanced Members
  • 1,681 posts
I wish to make my own dew shield for my 200mm explorer and would like to know what the proper astrozap ones are made of.

I was considering using roofing felt as it is black, non reflective, stiff and can be cut into whatever length is required.

Do people think this would be a good idea?

Also, what length are Dew shields normally, i.e. how far do they extend beyond the end of the scope in order to get decent dew reduction but not result in significant light loss.

I am hoping to maybe reduce the glare from my neighbours garage which seems to reflect the orange street lights, of which there are lots, directly down one side of my scope.

Any help much appreciated.

#2
Vega

Vega

    Brown Dwarf

  • Advanced Members
  • 2,503 posts
  • Location: Somerset
I'm not too experienced with this but wouldn't roofing felt run the risk of tiny bits falling on to your primary ? :shock:. Im sure someone will advise on the best material to use

Matt

#3
GazOC

GazOC

    Hyper Giant

  • Advanced Members
  • PipPipPip
  • 17,739 posts
For the length 1.5 times the aperture is the general rule of thumb.

#4
George

George

    White Dwarf

  • Advanced Members
  • 3,735 posts
  • Location: Stockport UK
I bought a aluminised ground roll from Decathlon http://www.quechua.c...am-mat-4219387/ on offer at 2.99 at Stockport branch, enough on the roll to go round my 10inch newt with enough left over to make half a dozen Hartmann masks :(

Gona spray it blue to match the scope but it already has a nice textured aluminium finish, just cut to-go round your tube, Velcro the full length and bingo cheapest dew shield possible :D

#5
Kai

Kai

    Bright Giant

  • Global Mods
  • 11,862 posts
Camping Roll is a good cheap dewshield,Its the thing you put under sleeping bags,only a couple of quid.

#6
tom.yates

tom.yates

    Brown Dwarf

  • Advanced Members
  • 2,439 posts
  • Location: Wigan /Greater manchester
8" Dew shield for sale on e bay at the mo astro engineering one

#7
beamer3.6m

beamer3.6m

    Sub Dwarf

  • Advanced Members
  • 1,681 posts
I have tried to make my own dew shield based upon your suggestions and here are the results.

Posted Image
(click to enlarge)


Posted Image
(click to enlarge)


Posted Image
(click to enlarge)


It longer than it actually is as the dew shield is pulled down by 5cm over the rim of the tube so I think I have a 25cm dew shield which based on the 1.5 ratio to diameter of the primary is not too bad.

I just need some clear skies to test it out.

Any comments welcome.

#8
George

George

    White Dwarf

  • Advanced Members
  • 3,735 posts
  • Location: Stockport UK
That should do the job, but looks a bit shiny inside....maybe a lick of matt black paint would do the trick :(

#9
iancandler

iancandler

    Proto Star

  • Advanced Members
  • 901 posts
An easy and cheap way to "flock" a flexible dewshild is to glue some black felt to the inside. you could get away with strong double sided tape to fix it or foam safe super glue (warning expensive for the good stuff from model shops)
  • tingting44 likes this

#10
beamish

beamish

    Sub Giant

  • Advanced Members
  • Pip
  • 8,474 posts
I too used a silvered camping roll and flocked the inside with self adhesive flock from a craft shop, available on aroll for about a fiver- works an absolute treat.

Karlo

#11
beamer3.6m

beamer3.6m

    Sub Dwarf

  • Advanced Members
  • 1,681 posts
I tried this out the other night and it worked a treat.

The scope was out for about 4 hours and not one bit of dew on the mirrors in all that time, and it was really cold on Friday. The outside of the tube was like ice and the eyepiece was dewed up, but not the primary or the secondary.

I am going to declare this a success.
  • tingting44 likes this




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users