8 replies to this topic

[Rayje1997]

Hello fine people, I was hoping someone could give me some ideas on controlling dew on my eyepieces and finder scope. I observe and sketch with my 8" dobsonian and I find that, especially when sketching for some reason, I have some serious issues with dew on my eyepieces. The finder gets me usually no more than an hour or two before it stars dewing up as well. I know I can buy some dew heater straps for the eyepieces and the finder, but to be honest I really just hate dealing with electronics while observing. If I wanted to fiddle with electronics and worrying about cables and batteries I would set up my astrophotography rig. 

 

So, does anyone have any suggestions for dew issues that don't involve electronics? If not, I will try to find some USB powered dew heater bands so I can use a basic USB battery bank.

 

Thanks in advance for any suggestions you have!

[Dynan]

Are you by AC? If so, bring a hair dryer. If you're limited to 12VDC, they make them for that voltage also, but those are serious battery drainers.

[Rayje1997]

Are you by AC? If so, bring a hair dryer. If you're limited to 12VDC, they make them for that voltage also, but those are serious battery drainers.

At home yes, but not always when I go to star parties. I don't really want to deal with running an extension cable but that is a good idea.

[izar187]

I keep my finders covered when not actually looking thru them,

with a common winter type knit hat, or sometimes a ball cap.

 

I keep my eyepieces in ep only cargo pockets on me, when telescoping.

Think fishing, hunting, shooting, photographers vest or field jacket.

3 season field jacket for me, that is large enough to layer up under, in cold.

Body heat keeps the ep's warm, de-fogging and de-frosting them between uses.

The field jacket is treated, so it is skeeter proof too.

 

Again, a cargo pocketed something, for astronomy only... and nothing else.

To keep ep's warmer than ambient, and sorted by size, at the focuser.

 

This combination has work for me for decades, in my climate, where dew is a problem.

Edited by izar187, 31 October 2024 - 08:29 AM.

[rjacks]

One of the many reasons I like using a Telrad as a finder is that there is no problem just wiping the Telrad with a cloth. I keep the Telrad covered, and it it does dew up, I just wipe it. 

 

If the temp is near the dewpoint, I leave eyepieces in their case, in the vehicle, to stay warm, so the only eyepiece that is out is the one I'm using. My vehicle is set up so that I can open and close the door without any lights coming on. I have eyepiece racks on my dob, but I only use them if dew isn't going to be an issue. If I can't have my vehicle nearby, I still leave the eyepieces in their case, and I throw an activated handwarmer in the case with them.  

[rgk901]

keep a heat strip in the eyepiece box to keep things warm...can also wrap the dewheater around the eyepiece itself if you are using it for a long time while sketching... svbony makes inexpensive ones

use long eye relief eyepieces with cup down and or use eyeglases even readers...

wrap same dewheater on finder

[Rayje1997]

I keep my finders covered when not actually looking thru them,

with a common winter type knit hat, or sometimes a ball cap.

 

I keep my eyepieces in ep only cargo pockets on me, when telescoping.

Think fishing, hunting, shooting, photographers vest or field jacket.

3 season field jacket for me, that is large enough to layer up under, in cold.

Body heat keeps the ep's warm, de-fogging and de-frosting them between uses.

The field jacket is treated, so it is skeeter proof too.

 

Again, a cargo pocketed something, for astronomy only... and nothing else.

To keep ep's warmer than ambient, and sorted by size, at the focuser.

 

This combination has work for me for decades, in my climate, where dew is a problem.

I kept the eyepieces I wanted to use last night in my coat pockets, which did help but the issue I was having was mostly with the one that was actually in the focuser. Covering the finder is a good idea, I could always just put the cap on it I suppose.

[izar187]

When dew is heaviest for me, I put ep's in pocket,

to un-dew them, while I use another for awhile.

Trading different magnification in and out a bit.

As a non power supplied countermeasure for dew.

 

Folks here on Cloudy Nights have also posted of success

strapping a chemical hand warmer to an ep while it is in the focuser.

I believe them, as that should work.

Those hand warmers are available most anywhere that sells

camping or hunting/fishing gear, including places like Walmart.

 

Perhaps try that.  : )

[Rayje1997]

When dew is heaviest for me, I put ep's in pocket,

to un-dew them, while I use another for awhile.

Trading different magnification in and out a bit.

As a non power supplied countermeasure for dew.

 

Folks here on Cloudy Nights have also posted of success

strapping a chemical hand warmer to an ep while it is in the focuser.

I believe them, as that should work.

Those hand warmers are available most anywhere that sells

camping or hunting/fishing gear, including places like Walmart.

 

Perhaps try that.  : )

Maybe I will try the chemical hand warmers trick. The reason I am looking for more than just putting the unused eyepieces in my pocket is because I like to sketch at the eyepiece, so often times the one I am using for that sketch stays in the focuser for an extended period of time. But now that it is cool enough for me to wear a jacket my alternate eyepieces will stay in my jacket pockets till I need them, which does help.