Dew questions

[darthvader]

Hi more noob questions....

If eyepeieces and/or scope get dew/condensation on them how bad is it?

Does it damage the parts long term?

Whilst they are still damp should I refrain from putting the protective caps back on and let them dry out inside first?

Normally when things get wet and then dry it out can leave water marks behind does this happen on mirrors and EPs too? Or am I worrying to much

Thanks

[Tinker1947]

A heated dew shield will stop the scope optics from dewing up, warm EP's before using will stop your body (Eye ) heat from affecting them, depending on your type of scope as to the type of prevention that works best. I use a hairdryer medium heat to warm up and dry them just keep the hair dryer away from the dew in a dry place.....

[CodnorPaul]

The biggest problem with dew is it will glue contaminants to your mirrors/lenses - but it does depend a lot on your type of scope.  SCTs are dew magnets and require fairly extensive dew control, reflectors not too much of a problem as the tube acts as a dew shield for the primary but the secondary can be affected as it is more exposed, fracs will suffer on the lense.  EPs can suffer but if you keep them in a pocket before use they are generally OK - I have dew control on my EPs, finder and corrector plate (SCT)

[rwilkey]

Hi Darth, it very much depends on your type of scope, some are more prone than others.  The above recommendationse are spot on.  With ep's I either keep them in my pocket or put them back in the ep case, just closing the lid so that they are still accessible.

[darthvader]

Its a SW 200P dob (must update my signature)

[Daz Type-R]

Hi, see my signature for all my dew kit on my 200P.

Like mentioned above, they are all good ideas but I dont want dew ruining what could be a fantastic nights observing, so i went all out and dew protected everything bar the primary (although that has dewed up once before - just as I was packing away one morning.)

Some people may say my set up is OTT, but I look at it like this, I have never, ever, had to cut an observing session short due to dew on the optics.

I have had 3-4 mm of ice on the OTA, other people have been packing up due to dew, not me, clear as a whistle all night!

Hairdriers etc are great, but when in a field at 4 in the morning, finding a 240 volt mains supply could be tricky, also, if in the back garden, if anybody else's hairdriers are anything like my wife's, then is sounds like a 747 taking off, may annoy the neighbours. - lol.

Just my 2p's worth.

[Moonshane]

I just use a dew shield for the scope (I use dobs from 6-16") and have only dewed up once - I was observing Jupiter at the zenith in a dew/fog bank.

dew on the outside which is what I assume you are talking about has no long term impact on the scope as long as you let it dry out the next day.

dew on eyepieces is a pain in some conditions but I usually keep my eyepieces in a foam lined case and if one dews over I swap them over for a bit and the residual heat in the (usually lid closed) box soon undews them. again when I finish I leave caps off until the morning to let then dry off naturally.  again no long term issues.

[Daz Type-R]

I just use a dew shield for the scope (I use dobs from 6-16") and have only dewed up once - I was observing Jupiter at the zenith in a dew/fog bank.

dew on the outside which is what I assume you are talking about has no long term impact on the scope as long as you let it dry out the next day.

dew on eyepieces is a pain in some conditions but I usually keep my eyepieces in a foam lined case and if one dews over I swap them over for a bit and the residual heat in the (usually lid closed) box soon undews them. again when I finish I leave caps off until the morning to let then dry off naturally.  again no long term issues.

WOW, I remember before I purchased all my dew stuff, I was out for only an hour and the secondary dewed up, suppose it's down to local conditions, you live high up???  

[Moonshane]

I live about 100m asl so not that high. at the end of the day we all do what works for us and creates enjoyable and productive sessions.

[darthvader]

Thanks for the tips ive not really suffered with dew yet but just wanted to make sure I knew how to deal with it when it happens.

I will make a dew shield when I get some spare time

[andyman]

There are a few things that can help prevention of due in the first place.try to observe in a open area where any slight breeze can get to the optics.also try not to view near any water source (streams, rivers, lakes) been there done that what a nightmare

[rwilkey]

Hi Darth, I just have a Celestron C8 dewshield on my 200P that I got s/h on ABS, works a treat and never had a problem, the secondary mirror is the most vulnerable.

[jason.p]

Hi Darth. I've got heated strips on primary, secondary, finder and probably most useful of all on the Telrad on my 200p. I've also got a dewshield. Again this is probably over the top, but I've got them so I might as well use them. Eps I keep in clean pockets in an "astro dedicated" coat, guaranteed not to be full of brick dust! You soon get to remember which one is in which pocket.

When I pack up I leave all caps off till the following day.

Good luck

Jason