Some like it hot!

[erick]

I had the idea of keeping my eyepieces warm in the colder, dewy weather since last winter (my first observing), and have worked up a heated eyepiece box.

The idea was to fit a heater strap inside a closed box and keep my eyepieces toasty warm (OK, a few degrees above ambient anyway).

I checked with John Marstiller at AFAB, the manufacturers of Dew-Not heating gear and he agreed that just laying a heater strap inside an enclosed space should work.

So I built a box and fitted it with a rack for my eyepieces. A rather rough wooden box, screwed together, but commensurate with my skills and functional, though not pretty. Plenty of measuring up to ensure there was sufficient space below the rack, particularly for the 10" dia heater strap to stand on end, but also for the protruding eyepiece and barlow barrels, including space for any fitted filters. Also space above the rack up to the lid for eyepiece height, including any 1.25" eyepiece in the 1.25"-->2" adapter. I added a bit of felt stripping around the edge of the lid, mainly to stop the lid banging noisily in the quiet of an observing night. A couple of eyepieces (my most commonly used 2" and 1.25") would have individual heater straps since they stay out the most. I filed some grooves in the top of the box for the heater cords to exit away to the Thousand Oaks four channel controller. I'll probably mount the controller on the side of the box (velcro) (The controller will also power a finderscope objective heater and a heater on the secondary mirror - maximum load on the power supply, everything on 100% is around 2A.)

Attached are some photos showing the result. There is sufficient space to remove the long heater strap. (I have ideas of wrapping it around my 100mm Binocular field lenses when I'm on a binocular evening.)

Now to test it out in dewy and/or cold conditions.

My intention is to mount the box at a height above the scope where I can easily access eyepieces while I'm sitting on my observing chair. I plan to simultaneously use the mount to provide a brace between the two walls of the base on which the scope sits, to keep try and stabilise the setup in preparation for a future time when I reinstall the encoders and purchase an ArgoNavis. (Yes, I know I will have to fit the brace/mount after the scope is in place and remove it to remove the scope from the base. Working on the best way to do this quickly.)

Thanks to Peter Read at SDM telescopes for prompt supply of the Dew-Not heaters and Thousand Oaks controller.

So far, so good. Eric :)

[Screwdriverone]

mmmmmm, toasty Eric.

Doubles as a Kebab warmer on those big nights out at the scope!

What a cool (or warm) idea! Might need a strip of reflecto tape on the sides or top so you dont bark the shins in the dark though?

Chris

[erick]

I go all black, Chris. I like to vanish into the background given I do much observing in places where I don't want to be spotted by trouble-makers.

And when I get finalised, it will be over a metre above the ground! :D

[OneOfOne]

Maybe you could cut a couple of holes in the bottom to stick your tootsies into! I must admit it is annoying when you can't seem to focus...only to find it is all fogged up :mad2:

[leon]

Wouldn't it be better to keep them as cold as possible so they won't dew up at the scope. :shrug:

I tend to cool everything down before an imaging event, have it all out doors hours before.

However clever invention, and if it all works, than that is what it's all about, nice job. ;)

Leon :thumbsup:

[rmcpb]

Leon,

If you keep the temperature of the eyepieces JUST above the dew point then they will not form any dew. The trick is to just warm them and not have them too hot because then you can introduce thermals.

Many people just keep a few eyepieces in their pocket and achieve the same but its nowhere as convenient.

[ving]

i am one that shoves eyepieces in pockets... but then theres the fluff factor...

looks interesting, i'll have jam on mine thanks :)

[Ric]

A very neat little setup Eric.

Well done.

[erick]

First real test last Friday night. Snake Valley. Grass was wet with dew soon after sunset. Scope very moist. Temperature dropped to around 3 deg C after midnight. Dripping fog was rolling in and out. My eyepieces were superbly dry and just warm to touch. No problem with dew formation or fogging up all night. I was able to cap them and pack them away at the end of the session. Checked the next morning and they did not need airing at all! :thumbsup:

[Wavytone]

While I like the idea of a heated eyepiece box - I can see myself making one in the near future - but if you have mains available I suspect there are cheaper ways to heat it, starting with the heaters used to keep pet reptiles warm "warm rocks" etc... these are under $50.

[erick]

Yes, I'm sure you are right. A year ago I saw someone using a folded up electric blanket and I did look for reptile flat pad heaters at that time to help him out. They were 240V, but I didn't easily identify a local supplier (didn't walk into my local pet store - a bit lazy :shrug:). When it came to buying heater straps, it was easy to add an extra one to the order and being 12V, I have mobility and controlled heating.