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dew shield's and dew heaters


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I have a question about using dew shield's and heaters. A wile back I got celestron 8" sct  as shown in the picture. I got it for photography use, When I took it out the first few times it would dew up very bad. Someone Told me to get a dew shield and that should stop the dewing problem. I did as you can see in the picture but I still get dewing. Not as bad  so I got a heater last november . The problem is that the dew shield wont fit over the heater. I put it on the tube just behind the window as shown by the white tape in the picture . I haven't had a chance to try it out because of weather. So has anyone setup a heater this way and will it work or should I look into getting a heated dew shield? Any advice would be helpful. This is my first sct any other scopes I have had have been small newt"s 4.5" range and I had little to no dewing problems.

thank you all 

jime

scope.jpg

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I think your guide scope dovetail is limiting the space available at end of the scope. The band really needs to be under the dew shield and as close to the corrector plate as possible for best results. It doesn't matter if the dew shield sits a little behind the dew band - but behind the dew band, heat will take longer to reach the corrector.

A colleague of mine used double sided tape to strap his dew band inside the outer rim that protudes from the end of the corrector - so the band sits right next to the corrector. It works very well keeping the plate clear. That would leave only the dew shield to strap round the outside of the rim. Hth :)

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As you are using a separate shield and heater cut a small slot in the shield so that it locates over the dovetail bar.

Put the heater band on first and make sure with the elastic part of the band (if is has one, mine does) again locates around the dovetail.

Then you need to adjust the size of the dew shield. I have found a half inch cross over on the Velcro allows enough diameter to slip over the heater. A case of trial and error.

 

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I want to thank all of you for your input .:happy11: I haven't had a chance to try it yet that is why I was asking for advice . I will try your ideas as soon as I can. Weather here has been yuck since November. The last time I was out the temp was cool so didn't need dew shield. This is still a little new to me, I have had the scope for two years now and the dew shield for about a year . The heater and controller I got the end of November so that has not been used yet that's why I asked for advice before I did something wrong. 

THANK YOU ALL :icon_biggrin:

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I also have an 8" SCT and made my own Dew Shield, I then fitted a home made dew heater to the inside of the dew shield and attached it with velcro strips. The dew heater is located about 2" in front of the corrector plate, I have been using this for about 4 years now with no problems and the dew heater is always there when I fit my dew shield.

Dave

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As per BW I cut a couple of slots in the dew shield so it goes onto the scope further, I just fit my dew band outside the dew shield just ahead of the corrector plate and never get dew on it even when it's running off and making puddles on the ground.

Dave

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