Dew shields/ heaters, avoiding damage

[Skade]

Hi, I just got my first telescope about a month ago. It's a Celestron 8se. I've set it up indoors just to make sure I knew how and that went fine. I haven't gotten the chance to actually take it out yet because it's been a snowy mess here for a pretty long time- there's been no good nights yet!

Anyway, all this is really besides the point... What I'm looking to ask is if before I try my first night, should I buy a dew shield/ heater?

I'm worried that if I don't use anything to prevent dew, I'm going to get my telescope covered in dew and damage it... am I being paranoid? Can dew be "lethal" to telescopes?

I've read conflicting information on exactly what you should do when you bring your telescope inside. Can some one explain it to me or direct me to some other related threads? I've read both that you should keep all the covers on and I've read that you should leave everything uncovered to let the dew evaporate. I'm confused.

[MrFinster]

I have a CPC800, a dew shield and dew heater are pretty mandatory given the UK climate, the collector plate will mist up quite readily.

When I have finished observing, I leave the cover off when the scope is brought indoors, when the front has dried off, I put the cover on as soon as possible. So far I have not yet had a problem with condensation on the inside of the corrector plate. 

[Mem]

I used to have a 6se this was my first scope and did not have a dew shield on my first few runs, although dew took some time to build up after 90mins use I found that in order to extend my time in the field I used a dew shield which gave me about 3hours use before dew started building up and ruining my night.

It's all about how much you have to spend at the moment? I initially bought the Celestron dew shield and once I had the funds bought a dew controller and band for the telescope which I used in conjunction with the shield and used together, I also bought a dew eyepiece band as the eyepieces do dew up very quickly, my advice is buy a 2" eyepiece band even though you may be using a 1 quarter inch eyepiece!!

No need to panic, you need to first get out and use the scope, the weather has been awful but In between the storms there has been some great skies! I know have a lightbridge12" dob not as portable as the se8, get out and enjoy!

[M4lcs67]

I have a C9.25 and I concur with the comments that a dewshield and heater are vital. You would however not damage the scope if you didn't. You just wouldn't be able to see anything once the thing had fogged up. The first time I used it, I just had a shield on and after an hour or so the scope was unusable as the dew had formed on the front element. 

On a side note. Once you have finished and brought the scope in for the evening you MUST leave it with all covers off to dry naturally before putting it away.

[Skade]

Thanks everyone for answering! So I ought to be shopping around for dew shields and heaters then. Any recommendations? I'm wondering, do any of you know of a cheap dew heater controller? They seem very expensive and I want to know if I'm just looking at rip-off sites or if the 100  dollar (60 pound) range is reasonable.

And as for bring in the telescope after use, any ideal position to put the telescope in? Like having the OTA facing up/downwards? I read that I should put it facing downwards, but I'd like to confirm that.

Thanks again!

[M4lcs67]

I use the Astrozap products and they are very good. Maybe a bit pricey, but they do the job. Some people make their own shields and heaters and that is fine, but for the rest of us who don't want to be messing about making their own, having things that are purpose built for the job if great. With regards to storage I just lay mine horizontally until it has come back up to ambient room temp then put all covers back on. Just check that all the moisture has gone first though.

[CodnorPaul]

Dew wont damage your corrector plate, but it can glue any contaminants to it making it dirty quickly, although that in itself does not damage views until it gets really bad (never overclean your optics).

I use that OTA on a new mount now and have the Celestron shield, and use a separate heater band behind it - but Astrozap do a combined one which I would get if I were starting again, and I also have one on my Rigel Quickfinder and on my EPs - you need to make sure you use a controller.  As for making your own, yes you can, but I would worry about creating hotspots and causing damage.  A controller and a few dew bands is a lot cheaper than a damaged OTA, and more worthwhile than cutting short your nights.

[Tinker1947]

My C11 remained in a Obby so there's no cool down time or packing away condensation, I use a Astrozap Dew shield/heater plus a second band round the out side no voltage control these just keep the correct plate clear the occasional blast with a hairdryer insures a clear corrector plate,  i brought a Desiccant Cap and placed 2 gel sachets inside the they lasted about 2 weeks before they went green (full of moisture) they were changed for a fresh sachets (the green sachets dry out on a radiator )  these have been in the cap for maybe 4 weeks no change of colour also a slight blemish either a shadow from the corrector plate or on the mirror about thumb size has dispersed so there's a nice shiny mirror, link to the D/Cap

 

http://www.firstlightoptics.com/dew-prevention/flo-125-2-inch-desiccant-cap.html

[Rockrae78]

You can of course buy a heated dew shield, which is what I use now.  You will still need a controller, but I just find that having to put just one thing on the scope eliminates some of the set up time.  I can't tell you the amount of times that I've put both the dew shield and dew band on, only to knock one or the other and have to do it again! 

Taking into account the price I paid for the dew shield and the price for the dew band, I think that the heated dew shield comes in at approx the same price (think it was a difference of £3!) 

I don't have a dew band for the EP, but I have been thinking about it recently.  Not too bad when I'm at home and can take the EP inside to dry off for a couple of mins, but out at a dark sky site, it would get very annoying to have a session cut short by a fogged up EP!

[Adrian Condon]

Hi,

I use a Kendrick Dew Controller to keep my Dob dew free.

See.....

http://www.kendrickastro.com/astro/dewremover.html

I have two home made bands, one around the primary mirror and the other around the secondary mirror.

I use Kendrick bands on the eyepiece and Telrad. All are individually controllable.

Plus I made a tube that extends from the secondary for about 20" out of cheap camping mat. Works great.

I also have a fan under the primary mirror.

I found that the best dew indicator is a bottle of Ouzo. It clouds beautifully before the scope fogs up.

The advantage of the Ouzo is if the dew becomes uncontrollable, you can give up for the night and drink the Ouzo!

I am currently looking at putting little heaters inside my eyepiece case so that they don't fog up before they are put on the scope.

Trust the above is helpful.

Cheers

Adrian

[MrFinster]

I found that the best dew indicator is a bottle of Ouzo. It clouds beautifully before the scope fogs up.

The advantage of the Ouzo is if the dew becomes uncontrollable, you can give up for the night and drink the Ouzo!

EEeeeeeuuuwww,  nasty.

There is another other liquid that goes cloudy when you add water and thats Dettol, that should tell you all you need to know about Ouzo, sambuca, pastise, absinthe and pernod. 

[Rockrae78]

EEeeeeeuuuwww,  nasty.

There is another other liquid that goes cloudy when you add water and thats Dettol, that should tell you all you need to know about Ouzo, sambuca, pastise, absinthe and pernod. 

You've obviously never had the good stuff! Had a try of some very nice Ouzo in Santorini a few years back and it was lurvley!! Never been able to get a decent bottle over here! 

And absinthe is pure delight! Just don't have too much of the stuff! 

[Adrian Condon]

Hi Rae,

You are welcome to another drink of Ouzo at SGL, just bring a glass.

I have never tried to drink Dettol......

Ouzo is good with sheep's brains and hot peppers I used to have when working in Greece.

See you there.

Cheers

Adrian

[maxheadroom]

Not read the full thread but get a dew shield and heater for the main lens. I'd buy at least a two Chanel and put a small one on your EP too. It's easy to breathe on it. If Michigan weather is like Britain then good nights are rare so not worth spoiling your nights viewing when it can be prevented with a small outlay

Max

[DeanB]

Should be receiving my Dewbuster soon, highly recommended, hand made and it has temperature sensors. US made too!

Dean

[Andy Milner]

Dean. Dewbuster Price looks good on dewbuster.com ? Is there customs charges for import I wonder?

Sent from my iPhone using Tapatalk

[DeanB]

Most probably, I'll inform you of the cost :-/

Dean

[Skade]

Thanks again for everyone's input! Sorry it took me a while to reply to this thread. So what do you guys think about these then:

http://www.astrozap.com/scripts/prodView.asp?idproduct=200

http://www.astrozap.com/scripts/prodView.asp?idproduct=238

http://www.astrozap.com/scripts/prodView.asp?idproduct=220

If I bought all of these, would I be set at least for a while? Also, can I use bigger eyepiece heaters on eyepieces that are smaller? Or is it necessary to get more exact sizing?

[maxheadroom]

Thanks again for everyone's input! Sorry it took me a while to reply to this thread. So what do you guys think about these then:

http://www.astrozap.com/scripts/prodView.asp?idproduct=200

http://www.astrozap.com/scripts/prodView.asp?idproduct=238

http://www.astrozap.com/scripts/prodView.asp?idproduct=220

If I bought all of these, would I be set at least for a while? Also, can I use bigger eyepiece heaters on eyepieces that are smaller? Or is it necessary to get more exact sizing?

Looks like great kit! I've used 2" straps on a laser and finder as well as eye pieces. They are flexible and versatile. You may find an 8" heater beneficial for the corrector (?) at the top of your scope it will sit just behind the dew shield

[AstroAdam]

I made my own dew bands, from nichrome wire all wrapped in heat shrink and gaffer tape.  Then I built a dual-channel dew band controller from some 12v dimmer switches that I rehoused in a new case.  Works a treat.  Lot less expensive - may not looks o nice, but works well

[Skade]

Looks like great kit! I've used 2" straps on a laser and finder as well as eye pieces. They are flexible and versatile. You may find an 8" heater beneficial for the corrector (?) at the top of your scope it will sit just behind the dew shield

Sweet, that's good to hear! Hopefully I'll finally be on my way to actually getting out and observing soon!

I made my own dew bands, from nichrome wire all wrapped in heat shrink and gaffer tape.  Then I built a dual-channel dew band controller from some 12v dimmer switches that I rehoused in a new case.  Works a treat.  Lot less expensive - may not looks o nice, but works well

I totally want to try making my own some day.  I have next to zero experience in anything like that though and I'm afraid of screwing up and ending up spending more money than I have too lol

[DeanB]

Well, got notification of Customs cost on the Dewbuster, £11.08 VAT and £8.00 for Parcelfarce. I regret keeping watch in the tracking;

Posted Feb 27, 3 days in New Orleans, 3 days in Chicago, 7 days(!) in UK Customs. Hopefully delivered tomorrow. Now just need to get some Dew-Nots!

Dean