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Dew control for C9

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#1 old_frankland

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Posted 23 November 2012 - 05:03 PM

Dew on the corrector plate is becoming more of an issue as we move into the winter months. I have been using a hair dryer to remove the mild dewing from the C9 corrector plate, but I'd now like to invest in a good dew shield with a heating strip to control the dewing. Astrozap offers a lightweight dewshield with heating strip that looks like it would do the job. Are heating strips effective with the large corrector plates? I have used them with smaller aperture refractors with good results.

Thanks.

#2 Jeff Smith

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Posted 23 November 2012 - 05:09 PM

Yes.
I have used heating strips with apertures up to 14" with success.

#3 old_frankland

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Posted 23 November 2012 - 05:17 PM

Thanks for the input, Jeff. How long does it take for the heating strip on the 14" corrector to reach a temperture that stops dew formation? Was the heating strip used in conjunction with a dew shield?

Thanks.

#4 wky46

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Posted 23 November 2012 - 05:29 PM

Hi Jim. Blow dryers are a hassle and I would rather be proactive in regard to moisture on the lens. Most nights here I have to use a dew strip. One for the lens and one for the EP. I have to deal with heavy frost as well. I have a dew shield but it only works for a little while so I never put it on and just use a dew strip, and thats all I need. It seems to work immediately on my 10" but it has to be placed just right and snug over the corrector. It keeps the dew and frost away all night long.

#5 old_frankland

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Posted 23 November 2012 - 06:16 PM

Thanks, wky46. What brand of dew strip are you using?

#6 Jeff Smith

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Posted 23 November 2012 - 06:49 PM

Thanks for the input, Jeff. How long does it take for the heating strip on the 14" corrector to reach a temperture that stops dew formation? Was the heating strip used in conjunction with a dew shield?

Thanks.


I have always brought the scope out an hour or two before sunset and aligned right at sunset. At that time I turn on the heaters. I have never had a dew problem. So in other words, the heater keeps up and never allows the dew to form in the first place.
Hope this helps :-)

#7 old_frankland

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Posted 24 November 2012 - 12:01 AM

Jeff, considering your location, your input is MOST helpful.

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#8 wky46

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Posted 24 November 2012 - 07:29 AM

I used the Dew-Not strip for years. The wires from it got damaged but luckily I repaired it and it lasted for a couple years afterwards but finally quit working. I ordered a DewZap brand this time and it's working fine. I've noticed that since I was using a blow dryer inbetween dew strips, my corrector had gotten very dirty from the minerals, dirt and pollutants in the moisture

#9 old_frankland

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Posted 24 November 2012 - 04:58 PM

Good point about constantly drying moisture on the corrector eventually leaving a residue. It makes sense that if you prevent condensation in the first place, the corrector surface should remain clean(er).

Thanks.

#10 n1wvet

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Posted 25 November 2012 - 01:49 AM

I've had good luck for several years with the Dew Buster controller and Dew Not strips. I have also built a few strips from scratch. Key is to turn on the dew buster system before dew starts. I turn it on as soon as I set up my scope. A good insulating dew shield also helps like and exercise mat repurposed for dew avoidance. Easier to prevent dew than trying to remove it after the fact. Kinda like poison ivy.






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