12 hairdryer for anti-dew

[albedo0.39]

I'm wondering what the best solution apart from anti dew tape, that people have found for the demisting the secondary mirror.

12v hairdryer ? - what's the weapon of choice and from where ?

Rechargable hairdryer ?

I have an idea to get hold of a low power light bulb from a mag-lite torch and mount in a sealed unit (light tight of course) onto the back of the secondary. Left running, the heat would sink into the mirror cell and keep it clear.

Not much power required, cheap and effective

Thoughts welcome

[roundycat]

I have never used a Newt so can't really say but I have used a hairdryer on my SCT and it causes huge problems with air currents and general loss of focus. If you don't play the hairdryer over the corrector for long enough it doesn't do anything anyway. Your idea with the small lamp sounds like a good one. Try a non-Maglite lamp though, one that chucks out more infra red.

Dennis

[Parallax]

You may want to hae a look at http://stargazerslounge.com/diy-astronomer/76981-secondary-mirror-dew-prevention.html

[brianb]

I'm wondering what the best solution apart from anti dew tape, that people have found for the demisting the secondary mirror.

When I had a closed tube 6" Newtonian I had few problems with secondary dewing (and none with primary dewing), on the odd occasion that it did happen I just held the metal support with an ungloved hand for a minute or so, the heat conduction evaporated the dew effectively.

If I had a lot of problems with secondary dewing I'd "move it down the tube" by adding a lightweight dew cap to the top. Sticking a heating pad on the spider support would be very much a last choice option.

[albedo0.39]

DOH ! - Top link to the resistor mod - I now feel totally ashamed at my technical skills (one time power & controls engineer from a few years ago) for not even thinking that...

I must have written the post when I had memory lapse..

[Astro_Baby]

I use a dew cap which keeps most of it out. With that said I have only had to cope with severe due once.

I also have a 12v hairdryer which seemed to work quite well last year at Salisbury. My scope was unaffected having a dew cap but Astronuts dob was dewing super bad and the hairdryer seemed to work. Its cheap as an option for sure and you can use it for de-dewing EPs and anything else as well.

There are dedicated heaters for secondaries but personally I'd be nervous of the heater overdoing it, melting the glue holding the secondary on and then having the secondary fall down the tube onto the primary. Yeah I know these things are thermostatically controlled but so was the fan heater that overheated in my flat and burnt a HUGE hole through the carpet

I got my hairdryer from ebay I think - it only cost about a tenner.

[Bigwings]

12V hairdryer for me except when I am in the garden facing south just outside the conservatory in which case I use a mains one. This warms all optics and my hands feet and other things that get cold.

[Doc]

All my observing has been done in my backyard so hairdryer run of the mains.

One day I will fit a secondary heater via a dew buster. I think that is the way to go.

[Taff]

I use a hairdryer when there is dew on the EPS at low setting it does it's job with no probs.Mark

[The Warthog]

It can also be used for drying your hair...