Dew band - temperature differences

[AlistairW]

Hello,

I have dew bands for my refractor, and also have a small temp gauge. If I know the outside ambient temp, is there a rule of thumb as to what temp the dew bands should be set to - to stop dew forming ?

Thanks

Alistair

[MarkyD]

You will also need to know the humidity to calculate the dew point

http://www.dpcalc.org/

--

Mark

[AlistairW]

Ahh yes - thanks for pointing that out. I will take a look at your link.

[astronymonkey]

I tend to set my bands as middle setting and have hever had any problems. If the tube starts to dew up then I turn the bands up a bit and likewise if everything is bone dry then I turn them down. It will also depend on the thickess and size of the lens, objective or mirror and power of the dew system so I dont think there is any specific rule apart from trial and error.

cheer

 

[baggywrinkle]

The difference between dew and no dew is around 1/10 Deg C, however as there is a larger area of glass and metal to warm to keep that difference a halfway setting to begin with should help. The advice from Astromonkey is good. Plus it consumes less power if you are on a battery.