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Originally Posted by gregbradley
No. I think most scopes are reasonably waterproof.
Dew control is:
1. Fans blowing fresh air over the optics (gets rid of thermal boundaries as well plus equalises the mirror/lens better).
2. Insulating the tube - on the RHA I have thermal blankets which are like wetsuit material that wraps around the tube and has a Velcro fixing. I have used windscreen insulation type material that wraps around a refractor objective area of the tube and that seemed to delay the onset of dew very well.
3. Dew heaters.
4. Dew shield.
A combination of the above works well. I have not seen dew on the RHA since I installed a dew heater. I am not sure if the blankets are needed anymore but I leave them on anyway. Without the dew heater dew seemed to only form right near the end of the night when the scope finally dropped down to ambient. The insulation delays that cooling and so the scope optics are always lagging behind ambient temp drops.
I have found in summer its less of a problem and is more of a winter issue.
The other concern I had about dew was staining of the optics which may be hard to clean.
Greg.
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At this stage all I am most interested is keeping equipment in good condition, not wanting to have any dew issues around electronics (definitely want to cover the EQ6 Pro face plate where all of the connections are. Could simply just use a strip of Gladwrap as a super cheap way of keeping dew off of all those electronics/cables/connectors.
Telescope has a retractable dew shield, buying a dew heater for it next week (should probably get the right size as opposed to a 10" one wrapping around it twice) so I won't have any issues around the lens. Was mostly wanting to keep the rest of the refractor in tiptop condition, unsure whether due could cause any problems there long term. Still likely to be quite some time before I have a more permanent setup going, shed with retractable roof should drop the amount of dew considerably, being semi-enclosed and all. Doing the same thing that you've done with your RHA does sound like a good idea, will have to do some looking into getting materials.
I actually built a small fan unit for my 10" SCT a couple of years ago, slowed it down but it didn't have a dew shield so mother nature still beat my little computer fan. If I do ever have an issue with the 130mm lens I can just attach the fan to the front of the dew shield.
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Originally Posted by AlexN
It's worth noting, I've had setups absolutely dripping wet during an imaging session and never had a drama. I keep the laptop set up inside one of those 30L storage tubs with a towel that drops over the front to stop light spilling out and keep warm in. That keeps the computer and it's transformer dry. I keep all the power inside a plastic tool box. An extension lead runs from the verandah into the box, contained within the box is a 12v 30A power supply that powers the mount, focuser and dew control. There is also a power board in there that feeds power to the camera and the laptop. Everything else is exposed...I found ccds generally stay dry as the body is usually warm.. I've had moisture running down the length of ota's and dripping onto the ground without problems. So long as you can keep your optics dry you are set.
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That's good to know. This is just me buying my first telescope that I am planning on leaving out all night over and over and over. Little paranoid! Hasn't even arrived yet
Picking it up in the next week or two, hoping to have everything setup so I can get straight into it.
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Originally Posted by glend
I have heard that a space blanket wrapped around a scope is an effective dew shield. Dew does not fall from the sky but rather moisture condenses on surfaces exposed to the 'cold' of space (the night sky). If you can place something between the scope and the sky then you can stop dew formation mostly. You can also try the quilted windscreen sunshields, I have heard they work. The shroud on my 10" truss newt gets soaked but the mirrors stay dry, and this is the case for most shrouded scopes. Just put a barrier up for the dew to settle on (a sacrifical barrier if you will) and the internals should stay dry.
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I actually did something very similar with my 10" SCT. Went down to Riot and bought some heavyish card and taped it around the front of the OTA as a sacrificial dew catcher, worked really well.