What to do about dew?

[Dendroica]

My astronomy has got more serious recently and I need to do something about dew.

I'm going to start off with a dew heater for the eyepiece and the secondary.

Will these be suitable for both? http://www.firstlightoptics.com/dew-prevention/astrozap-dew-heater-tapes.html I'm hinking they might be narrow enough to wrap around the secondary stalk.

I note that Kendrick do these which are secondary specific but they cost a whole lot more. http://www.kendrickastro.com/newtonian.html

I'm planning to use this as the controller. http://www.kendrickastro.com/newtonian.html Any other suggestions?

I'm planning to power them with a Tracer 8 or 10 Ah battery (which will also power the Nexus)

I'm a purely visual observer.

Any advice welcome and thanks in advance :-)

[Peter Drew]

You suggestions seem sound. Eyepieces and secondaries are more likely to dew up than the primary. It is easier to prevent dew than remove what has already formed. 

[damnut]

The secondary heaters from Kendrick are really good, and are shaped to the secondary so they do not intrude into the optical path. They are usually $30 - $50 USD.

The battery should be fine as you can reduce power to the secondary to around 20%. The dew controller is nearly £110   :-- http://www.tringastro.co.uk/kendrick-dew-control-147-c.asp

[Tzitzis]

What is dew and dew heater? I'm sorry but I have no clue :$

[faulksy]

What is dew and dew heater? I'm sorry but I have no clue :$

dew is moisture on your eps and mirrors. dew heaters are some kind of resistance wire usualy nichrome or similar, when a small amount of power is added they warm up, heating the glass surface enough to stop condensation. usually or best is to add a controller either a manual or you can get auto ones which measure the air temperature and adjust accordingly

controller http://www.firstlightoptics.com/dew-prevention/hitecastro-four-channel-four-port-dew-controller.html

and heater tape http://www.firstlightoptics.com/dew-prevention/astrozap-dew-heater-tapes.html

[Tzitzis]

Crikey these things cost... I guess anyone who lives in places with high moisture has these problems...

I live in a place without so much moisture and the climate is perfect... Not too cold not too hot...

[Gutross]

dew is moisture on your eps and mirrors. dew heaters are some kind of resistance wire usualy nichrome or similar, when a small amount of power is added they warm up, heating the glass surface enough to stop condensation. usually or best is to add a controller either a manual or you can get auto ones which measure the air temperature and adjust accordingly

controller http://www.firstlightoptics.com/dew-prevention/hitecastro-four-channel-four-port-dew-controller.html

and heater tape http://www.firstlightoptics.com/dew-prevention/astrozap-dew-heater-tapes.html

i have abunch of Kanthol 36G that i dont use anymore, i may try and make my own, i also have a bunch of 220 resistors, those should work as well

[triton1]

I use a camping mat as a dew shield and as yet have never suffered with dew on the secondary might be worth trying first as it,s a cheap fix and uses no power.

[Gutross]

i found a decent website for dew heater constuction if you chose to DIY

http://www.blackwaterskies.co.uk/2013/05/making-your-own-nichrome-dew-heater.html

[faulksy]

i made my own, i used 330 ohm 1/4 watt resistors and soldered them in parallel to make a ladder. work great with pwm controller

[laudropb]

The dew shield that I use works fine for the secondary, but the eyepieces are still a problem.

[Gutross]

i made my own, i used 330 ohm 1/4 watt resistors and soldered them in parallel to make a ladder. work great with pwm controller

i could see if you left them in a paper strip they come in and soldered it together it would make it alot easier

[faulksy]

i could see if you left them in a paper strip they come in and soldered it together it would make it alot easier

quite close together though. but maybe

[Gutross]

quite close together though. but maybe

you could solder every third of fourth to space them out

[Dendroica]

Thanks everyone for your replies.

[RT65CB-SWL]

What is dew... I have no clue :$

Dew is where the cold air meets the warm air, though not enough to form a visible mist or fog, (except on your optical hardware). Please feel free to correct me if there is a more accurate answer).

...I live in a place without so much moisture and the climate is perfect... Not too cold not too hot...

Definately in the 'Goldilocks zone' then!

[Dwayne]

I am still awaiting delivery of my scope , sometime today  . I quite often leave my camera clicking away at night for star trails and often had dew problems on my telephoto and remembered that I had used oxygen triggered heat pads to keep my batteries warm in Norway in winter , I tried these under the camera rain jacket wrapped around the lens and it cured the problem for 4-6 hours , when my scope arrives I will use an emergency reflective blanket make a couple of pockets to fit heatpads in and seal with velcro , I have no idea whether the fix for my camera 400mm lens will scale up and work with an 8" scope , but can't see why not 

[Tim99]

I recently bought a DewBuster controller and on the website are instructions for make your own heater strips.  I bought a strip for the telescope but plan to make the ones for eyepiece, diagonal, finder scope etc.  DewBuster.com     P.S. if you have questions, you can email the guy who makes these controllers and he will get right back to you.

[Gazabone]

The last few times I took my C8 out I've just put the dew shield on without plugging in the heating element. Tonight though after a couple of hours, it was really bad so that'll another wire that will have to plugged in in future! M31 looked positively uninspiring, combination of dew and a near full moon......