Dew shield

[zainraza]

I've been looking at different dew shields trying to find the right one for my scope but am wondering what size is the one that fits.

On FLO it says, for example, '8" Celestron Edge HD'. Does the 8" refer to aperture or focal length or something else?

thanks

[bcfcciderhead]

That will be 8" aperture, but don't pay over the odds and buy one do what most do and make your own out of some foam camping mat, it works just as well

[Ant]

If this is your scope...?

then you don't need a dew shield.

A newtonian (with the mirror at the bottom) is quite resistant to dew - the only thing that may happen is the secondary mirror may dew up. But I have had a number of newt and that only happened one or twice.

Ant

[zainraza]

Yeah thats the one

Wow did not know that, I just had it out yesterday and when I went to take it in the optical tube was a bit wet so I thought the mirrors might have been affected too.

Thanks for the info

[Damo636]

A homemade dew shield has other advantages. It helps keep stray light from getting in at the focuser end of the ota thus improving contrast at the eyepiece.

[zainraza]

I actually have a mat and so may use it for that

Do you just wrap the whole optical tube in the foam or a certain part of it?

[bish]

If you do buy one from FLO just give them a call and give them the tube diameter and they will send the right one - of course home made is always the cheaper option. Most of the time my newts don't suffer from dew but some places I go it is essential as the secondary dew over fairly quickly.

[JamesM]

You only need to wrap it around enough of the end of the scope to ensure it won't fall off. If you ensure that your dew shield extends by around 10" that will easily keep the dew away from the secondary mirror (the small one at the top). The primary mirror is too far down the tube to be affected. Don't need to paint it black (paint will come off) just use a mat that is dark in colour.

James

[zainraza]

Ah I get it now, I actually have a large elastic band that is usually used to keep the mat rolled up so that'll hold it up.

Yeah, it's dark blue so I should fine

Lucky me then not having to spend anything as I already have my own 'dew shield'

[Stephen]

I've just bought a brown one (darkest colour) for the princely sum of £3 off fleaBay - better safe than sorry I guess