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Dew Protection
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Cold weather observing has become my favorite time of year.
It's not that I really enjoy the cold weather. But the cold brings galaxy
season and crystal clear weather conditions at my observatory. As I
observe with folks, I find that they are never prepared for the cold
weather. Make sure that you read the review on cold weather clothing on
this site. On this page, we will be looking at heaters and dew protection.
If you want the best in dew protection for your optics in cold
and wet conditions, you'll be looking at Kendrick's products before long.
The system consists of four basic items. First and foremost is the dew
shield. Kendrick makes the best flexible dew shield. It is made of a
black rollable plastic as is the Orion model, but Kendrick goes one step further
and lines it with a black felt. It makes the shield stiffer and less prone
to light reflections.
Components two and three are the controller and dew
heaters. Kendrick makes several heaters that can be plugged into the
controller. The controller has four RCA female sockets to receive plugs
from the heating elements. Heating elements come in a wide range of
sizes. If you are using a mounted scope, make sure to get one for your
objective and your eyepiece. You will also want to get one for both ends
of your guidescope and one for your Telrad pointer. Oh... that's five
heaters and just 4 plugs. You can get an RCA splitter at Radio shack for a
couple or three dollars.
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The elements' craftsmanship is first rate. Each is
enclosed in protective fabric. The slick side goes against your optics/
The fuzzy fabric side out. On the end of each eyepiece/objective element,
is some elastic material and velcro for easy attachment to itself when you
wrap it round. The elements are sized by diameter. I use 2"
heaters for my eyepieces.
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They work well for all of my 1.25" eyepieces and will
barely fit around my large 2" eyepieces (Naglers). The 2" heaters will
fit around most other 2" eyepieces with no trouble. If you view
mostly with large Naglers, you may want to consider using 3" heaters
instead.
The Telrad heater is sort of a rectangle shape. When you
look at it, you may ask, "How does this thing attach?". It's
very simple. You put it on the side of your Telrad, where it fogs up, and
secure a rubber band around it and the telrad. The rubber band sometimes
gets in the way of your switch, but it is a minor inconvenience.
For a look at how these things appear when setup, take a look
at my observatory setup in my observatory
pages.
Kendrick also makes a fine battery pack. I consider them
somewhat expensive. Power is power and a sealed battery is pretty much the
same wherever you go. Wallmart and Costco sell emergency battery jump kits
for around 60 to 80 dollars. I purchased mine at Costco. It has a 34
amp hour battery, and emergency light, nifty LED's that give charge status, two
12 volt sockets, and cables to help start my car in an emergency. The
Kendrick 17 hour pack comes in a very nice Cordura pack and is somewhat
compact. Costco... $57, Kendrick $109. Take your pick.
The cheaper route Chemical heaters
Okay, you don't want to spring for the Kendrick system. The
costs for all those heaters adds up. A controller, battery pack, power
source for recharging.... it can get to be a real hassle.
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| A great solution is to use Grabber handwarmers.
These are available at REI
for minimal cost ($1.80 / pair). I frequently use these with my
Obsession. The big dob scopes don't lend themselves well to having a
battery and cable hanging off them. In addition, the primary and
secondary tend to dew up far less frequently than the eyepieces. |
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To use these chemical warmers, carefully slice open the top of
the plastic envelope that they come in. Save the envelope! Shake up
the warmer to get it started. Place the warmer next to your eyepiece, place the
plastic envelope on the outside of that, and a rubber band around the two to
secure them in place. The plastic envelope helps redirect the heat to your
eyepiece or objective. If you are using one of these heaters on a primary
objective, orient it on the bottom side of the scope tube as opposed to the top
side... they work better that way.
On a really cold night, these chemical heaters can really come
in handy as pocket warmers too! Imagine that.
The really cheap solution
It's hard to imagine that there is a very simple solution for
a problem as serious as dew. Just keep your eyepieces in your pocket and
your finder covered when you aren't using it. I've learned to use the
telrad even if it is covered with dew. It isn't optimal, but it isn't
terrible difficult. If you layer your clothing, your inner shell should be
a down parka or polartec jacket. A pocket in that inner layer is always nice and
cozy. Eyepieces love it there. Yes, even I sometimes take the really
cheap route when it comes to dew!
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