Dew Shield on LB

[PCH]

Hi :),

I see some iis'ers use a dew shield on their dobs (made from polycarbonate film or the likes).

Will this stop dew forming on both primary and secondary mirrors? Also, what's the best setup on a dob to prevent dew forming? For eg, do I need a heater aswell?

Appreciate your time. Cheers :thumbsup:

[rmcpb]

If you don't have a shroud on your Lighbridge then the dew shield will do nothing for your primary. However, if you do have a shroud then the dew shield will essentially be an extension of the OTA "tube" and will help greatly with dew on both the secondary and primary.

Its a bit ironic that the angle of best seeing ie. almost straight up, is the worst for dew formation on your mirrors though :)

[PCH]

Thanks Rob,

I do have the shroud so I'll go and get the pc film to make the ds out of.

Have a great day :thumbsup:

Cheers,

[astronut]

Paul,
I've had my dew shield on my 12" LB for two years now.
It has stopped all but the absolutely wettest nights.
For those I have just installed a secondary dew heater.

John.:thumbsup:

[PCH]

Thanks John :thumbsup:

may I ask what your dew shield is made from, how you've fastened it, and approx size etc ?

Cheers :D

[astronut]

Hi Paul,
It's made from High Impact Polystyrene Sheet or H.I.P.S. for short.
Light, strong, and flexible and a large sheet is approx $20.
I've attached it all with velcro.

[rmcpb]

What did we ever do before velcro??

[madtuna]

I heard we used sliced bread

[PCH]

John and guys,

thanks very much indeed for this info :thumbsup: Now I can be sure I'm going to end up with the right thing. Your help is much appreciated.:)

Cheers,

[White Rabbit]

So where did you get the H.I.P.S from?

[astronut]

www.allplastics.com.au (http://www.allplastics.com.au) at Chatswood.:thumbsup:

[§AB]

I'm planning to make a dewshield for my 12' dob, any locations in Melbourne where this material is available?

[astronut]

Sab,
Try plastics suppliers in the Yellow pages:thumbsup:

[§AB]

^^ cheers :)

[PCH]

Hey John,

I just called our local plastics supplier, and they've complicated the issue by asking ...
"what thickness?" :P

Do you recommend a particular thickness? They offered 0.75mm, 1mm, 2mm and 3mm. What have you used?

Cheers,:thumbsup:

[astronut]

Paul,
Mine is 0.75mm thick. I've found this to be very strong and flexible.
Any thicker than 1mm might make it difficult to bend.
These sheets are used primarily for counter fronts for shops, and are usually laid flat.:)

[PCH]

Thanks John,

the store had that thickness in stock. Appreciate your trouble :thumbsup:

Cheers,

[JethroB76]

Be interested to hear what you come up with, when I was in Melbourne last I tried a few places without luck, I think a plastics wholesaler out Dandenong had some but I didn't get out there

[Roger Davis]

Profile Plastics, Bayswater

[JethroB76]

I did try there; I was staying right around the corner, but they only had heavy stuff at the time....I'll have to try them again at the end of the month when I'm over

[Dave47tuc]

Many people have asked where i got my dew sheilds from.
Well I work in the printing industry, but a good supplier is ,
http://www.mulford.com.au/main-frame.htm

:)

[JethroB76]

Mulford is the one I found out Dandy way, I spoke to them on the phone and they had the HIPS, but I never got out there

[PCH]

Mulfords do definitely stock the black Hips sheet, and for the size I required for the LB 12, the sheet cost less than $11 - great value ! In fact the velcro was more expensive at $15 :P

Cheers,