Dew Controller

[Nortilus (Josh)]

I'm looking at getting a dew control system. So far looking at the Kendrick Digifire 7 but not so sure what heaters to get. I have a GSO 8" Newt, a 80mm short tube refractor as guide scope and a 50mm finder scope. I'll also be adding a QHY9c to this shortly and heard that you can use a heater on the outside of these to help stop moisture on the unit itself.

Would the following be sufficient?

Controller
http://www.bintel.com.au/Accessories...oductview.aspx

For the primary
http://www.bintel.com.au/Accessories...oductview.aspx

For the 80mm Primary Lens on the guide scope
http://www.bintel.com.au/Accessories...oductview.aspx

For the finder scope
http://www.bintel.com.au/Accessories...oductview.aspx

However what is best for the secondary in the newt? Any suggestions welcome.

[Nortilus (Josh)]

no help on this one

[RobF (Rob)]

Hi Josh

To do this properly (and the links you've posted would certainly do what you want well) will add up cost-wise.

If you're still learning astrophotography, why not take it easy, and just make some passive dew covers from foam matting and velcro. A wetsuit fabric beer stubbie cooler makes a great dew cover for a 50mm finder.

I only ever use passive control on my 50mm finder/guider and 8" Newt in Bris burbs and surrounding dark sky sites, and with our pretty mild weather it has been fine. The 80mm refractor is likely to need something having said that, BUT you may well find you can still guide ok with just a passive cover on it initially while you're learning the ropes.


p.s. I have a Thousand Oaks 4 channel controller I use with an 80mm refractor with single dew strap and works great. No experience with Kendrick controllers. Would be worth searching past posts here for what people prefer with regards to reliability, connectors, etc too.

[Nortilus (Josh)]

i used to use passive control on the finder but still found i was getting dew in the early hours of the morning while doing visual stuff, and the secondary would be the same...

Im sort of trying to get 1 step ahead so that when i do finally start getting into it more im not getting setup and ready to start imaging then be all OMGs dew...fail...packup...

[MrB (Simon)]

Josh,

Might be worth having a look at the Dew-Not gear too.
If you order from ebay you get free postage:
2ch/4strap controller
3" strap (suitable for 80mm scope)

[RobF (Rob)]

Again, not talking you out of starting to buy some gear, but I regularly image all night with my 8" with a 12" foam extension and nothing but stubbie cooler on the finder. Haven't been stopped by dew affecting guiding or dew on secondary for over 3 years, working from Bris and surrounds.

The QHY9 doesn't seem to attract dew on its casing, probably due to warmth coming from cooling unit. Body of the OTAs frequently literally running with dew (or frozen solid as happened at Leyburn the other weekend )

[Nortilus (Josh)]

So you dont have dew control on the qhy9? Interesting to know...

[RobF (Rob)]

QHY9 mono has heating applied to the inner CCD window via a ring of resistors mounted around it on a little mini board. Most people also operate the QHY9 with the 12mm "window" that comes with it. I don't have a colour QHY9, but expect it might be the same.

You might be thinking of the QHY8 which did eventually have a heated adaptor made to heat its external window? (not required on 9 though). The QHY forums are a good place to hunt this sort of info:

http://qhyccd.com/ccdbbs/index.php?board=5.0