Dew Prevention

faramir · #1 26-08-2007, 02:13 PM

I am new to astronomy and have just purchased a meade 8" LX90GPS telescope. I have been very pleased with what I have so far been able to see with this scope. The go to ability makes it a simple process to view the offering available in the night sky with no knowledge of where to look. Given the price (more than the wife would have wanted me to spend) I was disappointed in the quality of the tripod and finderscope, but presume the other technology is what one is paying for. After just having learnt to use the scope and then been kept inside by weeks of overcast skies it was disappointing that with my first real opportunity to get out, that the collector plate dewed over within 10 minutes of setting up.
Looking at the Bintel site I find I could spend a lot of money on a kendrick system or purchase for much less a Orion flexishield and dew zapper. Is the Orion system going to be sufficient or should I save up and get a kendrick system with capability to heat the collector plate and eyepiece (Cant see the sense in heating the finderscope as I only use this during the alignment process when I first set up). I would prefer to only have to purchase once and if that means delaying the purchase and getting something that will be better suited but more expensive I would prefer to go down that line. Interested in peoples views.

[1ponders] (Paul) · #2 26-08-2007, 02:24 PM

and

faramir.

I use the orion 20W dew strap on its own with no problems. Unfortunately you have no control over how hot it gets, so it is on full the whole time. You could use it in combination with the dew shield, that way the shield would protect it for most of the time and you could turn on the heater only when you needed it.

This option will sort you out straight away and give you the otion to save up for the Kendrick system for later.

faramir · #3 26-08-2007, 03:24 PM

Thanks Paul. I suppose the advantage of the kendrick system is that there is less power use. I intend to plug the scope into my cars accessory socket so presume power will be less of an issue for me. Don't see myself doing astrophotography in the near future and hence my observing sessions are likely to be limited to a few hours at most, further limiting the power issue. Sounds like I could also get away without the dew shield though for shorter sessions this maybe all I need and I presume a lot easier to setup.

Lee · #4 26-08-2007, 03:25 PM

You can also make your own dew heater - there is an active thread in the DIY forum at the moment - if you are handy with basic electronics I guess.

acropolite (Phil) · #5 26-08-2007, 03:26 PM

The orion flexishield works a treat, I have only had dew on the corrector plate once since buying the flexishield. I have a dewstrap, but have never had to use it. Another cheap solution is a 12 volt hairdryer. You need to exercise caution with a hair dryer as it is possible to damage the coatings if used incorrectly.

rumples riot · #6 26-08-2007, 05:58 PM

Faramir, I recommend that you get the Dew Buster which better and cheaper. It can be bought at OPT. Your enjoyment will be far better if the corrector is not overheated. Overheating spoils the sharpness of the view and hence will lead to you using the scope less. Better to get a quality system and have years of hassle free fun.

Also, just for your own information and others. The plate at the top of an SCT is known as a corrector plate.

Best of luck.

faramir · #7 26-08-2007, 06:23 PM

Thanks everbody. Your advice has been most helpful. Think I will go with the flexishield for now and start saving for the kendrick system or something similar in the future. Hope I am a bit more observant with my astronomy viewing than my terminology but wont forget now its the corrector plate. Though collector plate seems appropriate when it comes to dew.

rumples riot · #8 26-08-2007, 07:20 PM

Fair enough and yes, it is a collector plate;-). Go for the Dew Buster though when you get around to buying. They are only about 250 from memory and you only need one belt.

wolfman · #9 26-08-2007, 09:54 PM

Hi, I have a Orion Dew heater for sale in the Accessories section, its new and they work very well, especially if you use them with a Dew shield.

wolfman · #10 26-08-2007, 10:01 PM

In case you were wondering, the Kendricks system works at full strength and only uses less power because it switches off and on to regulate a lower temp, there is no real reason why you can't do this manually turning off and on as you see the need to coserve the battery.
Just a thought.

Geoff45 (Geoff) · #11 27-08-2007, 12:43 PM

I made my own from the IIS articles

http://www.iceinspace.com.au/index.p...63,285,0,0,1,0
http://www.iceinspace.com.au/index.p...63,292,0,0,1,0

by Alan Sheean. Cheap, easy to make and works well.
Geoff

faramir · #12 27-08-2007, 11:16 PM

Sounds like a nice little project Geoff. If I had the time I would probably give it a go, but with my limited background in electronics it would unfortunately take more time than I have got at present. What a big difference a day makes in regard to dew formation. Spent 2 hours observing tonight and not even a hint of dew on the corrector plate.