Dew / frost

[wormix]

Evening all,

Got prepared for an imaging session early today - all set up and ready to go, but have really struggled with dew on every surface. 

Was almost impossible to find my target due to moisture on finderscope and eyepiece, and when finally lined up realised the primary and secondary on my 150PDS where also frosted so I’ve had to call it a night without achieving anything. 

Is it the case that sometimes there is just too much moisture in the air and there is nothing you can do?  Not sure a dew band would have helped either tonight?

 

cheers

[joe aguiar]

Your always gonna have issues with either lp dew and frost in this hobby.

I find a dewcap is more than find for my needs. However if u live in a humid and dewy area/country then that may not be enough.

As I said in another post most people think dew is only a sct/ mak or refractor issue but it's not any scope optics may have this problem.

Since u have a reflector u may need a dewcap to extend futher out. Wrapping your whole ota or both.

If that doesnt work u may have to wrap dew strap powered around the 2nd mirror.

The tube is larger than  the mirror so putting a dew strap around the outside tube may not do anything.

Try 1st part if it works then great if not go 2nd part etc

The 3rd part could be a strap on the bottom of the mirror but I'm not sure if that work if not around the mirror itself inside the tube but I never had to go to these extremes for dew control

Joejaguar 

[Paz]

Dew conditions vary a lot where I am sometimes things don't dew up at all, sometimes they dew up quickly.

I only use heaters on my big scope, the rest I just use dew shields and accept that there may be a limit on how much time I have to observe. But my sessions are usually shorter than the time it takes to dew up.

[wormix]

I have never had it as bad as last night, so assume it was just one of those nights. 

There is water everywhere this morning like it’s been raining 

will explore a few shield. Any advice on fogged you EPs and finderscope?

 

cheers

[Jiggy 67]

25 minutes ago, wormix said:

 

will explore a few shield. Any advice on fogged you EPs and finderscope?

 

 

There are dew strips for finders copes and ep’s.

https://www.firstlightoptics.com/dew-prevention/astrozap-dew-heater-tapes.html

or consider a hairdryer 

[John]

I don't know where you are but we had very dewey conditions here (North Somerset, UK) last night. My scope and finders don't usually suffer from dew much but last night I was repeatedly having to clear the dew off the finders last night.

I keep my eyepieces at a bit warmer than outside temperature which stops them dewing / misting.

So as Paz says, depending where you are (including height above sea level and proximity to water bodies) dew formation can vary a lot session to session.

 

[alan potts]

I had dew on me last night, the guide scope had frozen over and oddly still managed to guide. I have to say though I felt cold, must be getting old.

Alan

[PeterW]

FLOs ClearOutside app gives an indication of whether it’s likely to be dewy. Still, cool, humid nights are the worst. Long extension tubes, dew bands, warmth, dew zapper/hairdryer...  sometimes there’s not much you can do. I had a very clear session once, only problem was it was very windy... only thing we could do was to use binoculars in the lee of a building.

peter

[wormix]

5 hours ago, PeterW said:

FLOs ClearOutside app gives an indication of whether it’s likely to be dewy. Still, cool, humid nights are the worst. Long extension tubes, dew bands, warmth, dew zapper/hairdryer...  sometimes there’s not much you can do. I had a very clear session once, only problem was it was very windy... only thing we could do was to use binoculars in the lee of a building.

peter

Thanks Peter, completely forgot about the dew point bit of clearoutside. 

I think it was just one of those nights, plus I am surrounded by water and after a reasonably “warm” day that couldn’t help. I won’t overly panic and go buy a load of heaters just yet!

cheers

[wormix]

Here we go again - acclimate early, looks like early part of the evening will be ok  

 

 

[maw lod qan]

Here in Fla I struggle with dew on the finder scope and lens. I put small 12v fans to blow air through the tube at the primary and that stopped the secondary from fogging.

Made a dew zapper for the finder, with a variable switch to control the temp.

When I set up the camera for wide field meteors I use a hand warmer packet in a cloth wrap. Works like a champ.

[paulastro]

I use refractors and always use an additional dew shield  on the end of the one that's already on the scope.   Dew shields supplied with refractors are nearly always inadequate - even expensive refractors come up short in this respect, literally!    I generally would expect to be able to observe for at least two or three hours with no problem on even the most dewy nights.  As for finderscopes, I just replace the caps when I have found the object I'm looking for if there is much dew.