What Do You Do About Dew?

[refractordude]

What is the easiest way to make dew shields for binoculars?

[NGC 1502]

 

I’ve made several dew shields for small telescopes from regular camping mat foam. It’s widely available from ‘outdoor’ type shops, is lightweight, doesn’t absorb moisture ( just gets wet ) and is easy to cut. No reason why it won’t be fine for binoculars.

I once found the foam in black which is ideal, but any dark colour would be ok.

HTH Ed.

Edited July 23, 2018 by NGC 1502
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[MarsG76]

Either just some tubes extending from the objectives or, if you want to get more techy, get some nichrome wire and make some dew heat strips.. poered by a 6Ah rechargable battery which will last ages and is quite small in size.

 

[alanjgreen]

Here is what I use...

[domstar]

2 toilet rolls slit up the sides and held with elastic bands.

[BinocularSky]

Cheap yoga/exercise mat. Can get it thinner than camping mats. Stitch velcro onto it to hold it in place.

[Bamo]

I used Yoga mat when dew is not very aggressive with a maksutov. With the refractor, although it came with a built in dew shield, but it's not helping at all. Some advised hair dryers.

[NGC 1502]

4 hours ago, Bamo said:

I used Yoga mat when dew is not very aggressive with a maksutov. With the refractor, although it came with a built in dew shield, but it's not helping at all. Some advised hair dryers.

Most built in dew shields are too short, but can easily be made longer using above methods.

If that’s not adequate, and it probably won’t be on chilly nights, there’s heating bands that gently keep the objective just a fraction above ambient, or a 12v hairdryer from a battery pack.

Ed.

[LukeSkywatcher]

Dew shields, should be about 2x the diameter of the aperture of the scope.

So lets say your scope has 80mm aperture.............make a dew shield 160mm long.

[Charic]

For scopes I thought the norm was 1.5 times the aperture, but no harm in experimenting.

Dew itself, I just go indoors and wait another night, if the scope is dripping wet.
Not noticed much dewing with my binoculars, so not had to retreat indoors just yet! 

Edited July 24, 2018 by Charic

[LukeSkywatcher]

12 minutes ago, Charic said:

I thought the norm was 1.5 times the aperture, but no harm in experimenting.

Its 2.5x, 2x is good.

[Charic]

 

Dew shield not really needed on my scope as the OTA itself acts a a good shield. The main reason I have used a shield on the scope is to prevent unwanted light from entering the scope.

[BinocularSky]

I make mine at least 3x, unless it would make them unwieldy. At 4.5x, they actually work properly! (see length of primary "dew shield" on a solid-tubed Newtonian ? )

[LukeSkywatcher]

Buy a dew heater strap. They work well. 

[BinocularSky]

22 hours ago, LukeSkywatcher said:

Buy a dew heater strap. They work well. 

And require power. Which my binocular doesn't.

[LukeSkywatcher]

10 hours ago, BinocularSky said:

And require power. Which my binocular doesn't.

You can still heat the bins.

[BinocularSky]

On 28/07/2018 at 00:40, LukeSkywatcher said:

You can still heat the bins.

Only by either stuffing them under my jacket - which initially makes the dewing worse - or by taking a heating/power source to my observing site. (I do sometimes take a battery pack and hairdryer when it's a public outreach event)

[Bamo]

On 23/07/2018 at 23:05, NGC 1502 said:

12v hairdryer from a battery pack.

Any precautions whilst using the hairdryer during observation?.

 

[BinocularSky]

4 hours ago, Bamo said:

Any precautions whilst using the hairdryer during observation?.

As a matter of habit I let it run for a few seconds (to expel any loose dust) before directing it across the optic, and obviously you don't want to touch the optic with it. At 12v, electrical safety isn't a major concern.

[Bamo]

Just an update; last night I've used a camping 12v hairdryer with Sky-watcher power bank 7Ah. I guess I turned on the hair dryer for a couple or 3 mins in total. I can tell that it sucked all the energy in the power bank. and I was left the rest of the night helpless!.

I'll need to think of something else. You can always go cheap but would it work?. In my case it just didn't.

[refractordude]

5 hours ago, Bamo said:

Just an update; last night I've used a camping 12v hairdryer with Sky-watcher power bank 7Ah. I guess I turned on the hair dryer for a couple or 3 mins in total. I can tell that it sucked all the energy in the power bank. and I was left the rest of the night helpless!.

I'll need to think of something else. You can always go cheap but would it work?. In my case it just didn't.

Sorry about your losing power, but did the hair dryer work to red your optics of dew? I just ordered a hair dryer that will be powered by my car battery.

[BinocularSky]

12 hours ago, Bamo said:

Just an update; last night I've used a camping 12v hairdryer with Sky-watcher power bank 7Ah. I guess I turned on the hair dryer for a couple or 3 mins in total. I can tell that it sucked all the energy in the power bank. and I was left the rest of the night helpless!.

I'll need to think of something else. You can always go cheap but would it work?. In my case it just didn't.

I'm not very impressed with the batteries they use in those power packs. Mine started losing capacity very soon after I got it. I replaced the battery with a Yuasa one (also 7Ah) about 5 years ago and it's been fine ever since; much better than the original.

[Bamo]

6 hours ago, refractordude said:

Sorry about your losing power, but did the hair dryer work to red your optics of dew? I just ordered a hair dryer that will be powered by my car battery.

Yes, the hair dryer will work fine. And as long as your powering from the car you shouldn't have much of a problem.

Good luck

Bamo

[refractordude]

6 hours ago, Bamo said:

Yes, the hair dryer will work fine. And as long as your powering from the car you shouldn't have much of a problem.

Good luck

Bamo

cool

[daveintheshire]

On 26/07/2018 at 12:33, BinocularSky said:

<snip> At 4.5x, they actually work properly!

Um....  You sure about this, Steve?  I think I might need third party liability insurance to take these off my own property! ?