This look about right for a DIY dew shield?

[thomasr]

As built, the dew sheild extends about 8" past the front of the OTA ... which is a little less than 1.5x the aperature, but I figured it's better to err on the "short" side since the "long" side might create vignetting or other weird effects.

[LukeSkywatcher]

A dew shield should be about 2.5x the aperture of the scope. Looks about right but maybe cut 2 inches off of it?. Looks a bit too generous to me.

[thomasr]

My aperture is 6", so 2.5x would put me a whopping 15" out front of the collector plate. The picture you see is only 8". Not sure if I should be adding or chopping...

[jambouk]

It looks good to me. Too long and they get floppy. Also a slight breeze and starts rocking the rig. You essentially need dew bands.

James

[thomasr]

Anbd here I thought that once I bought my new scope, I'd be done spending money ...

[Uplooker]

Anbd here I thought that once I bought my new scope, I'd be done spending money ...

ha ha ha ROFLMAO. That is the thought that most people on here start off with   It soon gets spent out of them, and that's if your only doing visual. If you go down the AP route that thought disappears quicker than you can say "Bloomin' Clouds"

I think your grand with the dew shield, but you really are best getting dew bands. Have a look at the AstroZap ones that have dew bands built in, such as this one:-http://www.firstlightoptics.com/dew-prevention/astrozap-flexi-heat-dew-shields.html

Good luck with the new scope, enjoy it

[thomasr]

Well I had my rig out for a solid 2.5 hours of observing last night and the optics stayed clear throughout. Mind you, the finder also stayed clear with no dew shield affixed, and I didn't notice any condensation on my car either, so this might have been one of those nights when I'd have been alright even without my hacked dew shield.

[RikM]

That looks about right for a dew shield but Paul is right. Generally longer is better. Dew band or a combo heated dew shield would be the ultimate.

For what it's worth, in astronomy, the telescope is the cheap bit! The accessories are what really get you.