Invest in dew prevention?

[milan]

So, still waiting for some clear nights, not had any for 2 weeks now, but since its starting to get cold should i be looking to invest in some dew prevention gear like the astrozap etc?

Having only get my setup a few weeks back ive no idea if dew is going to be an issue with imaging etc.

Thanks.

[Dangerous-Dave]

I think it depends how bad the dew is at your observing spot. My back garden gets very little dew, being on the top of a hill, fairly breezy with no standing water so I rarely need a dew band - just a dew shield and occasional hairdryer. However at Kielder everything dews up in minutes so I was very grateful for my dew control.

[michaelmorris]

I have a large dew shield and dew heaters. Whilst it is probably only between 5 and 8 times a year I need them, I'm very grateful when I do, as dewing tends to come on some of the clearest nights.

[Merlin66]

At least make up a dew shield from either a foam camping matress or a wrap of cardboard. Should be x1.5 the diameter of the scope long (+ a couple of inches to sit on the tube)

[assouptro]

I have just fitted astrozap dew shields to my scopes and can report they make a lot of difference as dew has always been one of my biggest problems and its surprising how loud a hairdryer can seem at 3am!

I would say yes either buy one or at least make one.

[milan]

Will be for use on a Megrez 90 which has a 'slidey' shield built in. Do the dew heaters go round the scope body or the shield?

Would i need anything for the end with the camera attached? Is so where would it fit? (i have a WO field flattener which attaches my Canon 5D to the scope)

[Merlin66]

generally the built-in dew caps are too short to do their job - a carboard/ foam extension will help.

Dew forms on external surfaces first, so the objective will be affected long before the camera.

The dew heater should be placed close behind the objective on the tube rather than on the dew shield. This will gently warm the lens.

[Dangerous-Dave]

I've got the Megrez 90 and it has one of the longest, best dew shields of any refractor I have owned, so I don't need to make an extension. The Megrez 72 on the other hand, dews up very easily so I have a piece of rolled up junk glossy junk-mail I pop over it. The ST80 is another scope with a fairly ineffective dew shield IIRC.

FLO advised me to put the dew band behind the slidey dew shield. It certainly appears to work that way.

[milan]

Okay thanks all. May give it a try first before splashing out the best part of £100.