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by Tom Massey
There may well be many dew prevention systems out there, but the one I have works. Dew, the worst enemy of amateur astronomers, CAN be virtually eliminated. I recently spent a few nights at our summer star party campsite and for the entire observing time - almost all night - I had no problems with dew. But, I was the only one.
The Kendrick System has already been reviewed in Sky & Telescope, but I failed to read the article and just ordered it after getting so sick and tired of taking astrophotos only to find out that, after guiding for 20 minutes, my corrector plate was dewed up. Call it impulse buying if you will.
This system is a neat package consisting of a controller with outlets for four electrical heat strips. The variable heating control is a nice feature, since you do not always need the high setting and it saves battery life. The strips are covered with nylon and have Velcro fasteners for installing on your tube. Attached to the strips are the power leads with telephone plug receptacles with sufficient length to reach the controller that may be placed at any convenient location with another strip of Velcro. The strips come in various lengths to fit different telescopes and accessories. I bought two to fit up to 9-inch tubes. I use one for my C-8 or Schmidt camera and the other for the finder, wrapping it around more than once.
While at the summer star party in August I first used the system only to find out too late that my battery was dead. However, when you have a fully charged battery the system will not let you down and apparently does not draw excessive current. I used it all night and used the same battery to drive the telescope and had no problems. It operates only on 12 volts DC and comes with a standard cigarette lighter plug. The battery of course is important. I use a 24 ampere hour battery that I picked up at a flea market that is more than sufficient for this system.
I plan to order additional strips for accessories like guide scopes and big eyepieces. Initially, the system is not inexpensive - the control box is $58.00 and individual heat strips start at $27.00 depending on length. If you had the material you could probably build it for a few dollars. However, for the convenience of not having to hunt up the parts and make and cover the strips, it's worth it to buy for the insurance of combating enemy number one.
I ordered the system from Pocono Mountain Optics and it was shipped to me in one day. Believe me, this little beauty will extend your observing or photography time indefinitely. This, I now realize, is a must item for anyone who spends time out of doors where dew is present. It gets rave reviews from this user.
