All Fogged Up

astroAJ · #1 10-07-2007, 03:14 PM

Hi all
I was star gazing last night and I noticed that my eyepiece kept fogging up. I don't do a huge amount of winter observing so I hadn't noticed this problem before. The problem is that I cant look at planets etc at high power because the fog covers my view.
Not sure if this is the smartest question but how can I reduce or get rid of the fog on the eyepiece.

Thanks

matt · #2 10-07-2007, 03:16 PM

You could buy a heater strip and plug it into a portable power source.

Without some type of heating it will fog up with dew, just as mirrors and corrector plates do, especially in winter.

Some guys also use a portable hair dryer to remove dew from surfaces.

Stephen65 · #3 10-07-2007, 04:16 PM

You can buy portable dew heater strips that wrap around the EP and keep it warm, they plug into a controller and run off a 12V battery source. I have dew-not strips for my scope and EPs and a Kendrick controller. You plug it in, flick the switch and dew is banished.

The other option is a battery operated hairdyer (I steal my wife's) - don't blast the EP at close range though, hold it back a ways! This only give you temporary relief from dew though.

Tannehill · #4 10-07-2007, 06:06 PM

Also, another option is to keep your EPs in a container of sorts (a case) or even a small portable cooler - a mini-ice chest - into which you set your EPs for the night, and drop in one or two of those chemical warm pacs wrapped in a small towel. Keep the lid on the case between EP changes, and the contents - including the EPs - will stay warm enough to prevent dew. Of course, if that EP stays out for a long time, it can still cool and dew up, in which case the above mentioned solutions are the best. EPs heaters, focuser warmers, etc.

I've a Pelican case for mine and have been considering installing a low-temp heating element in the bottom for such a purpose. They sell them at Kendrick...case heaters...for that same purpose.

Common problem I have when in the northern US is not dew per se, but condensation when my warm face approaches the freezing-cold EP: fogs up right away and is slow to resolve. less of an issue here, but in Wisconsin...hardy observers have been known to have damp eyelashes freeze solid to the (ice-cold) barrel of the EP, and require extrication by a partner. Another good reason to observe with a buddy, preferably one with a small hair dryer...or small scissors....

Scott

CoombellKid · #5 10-07-2007, 06:21 PM

A hair dryer is a handy thing

regards,CS

rmcpb (Rob) · #6 10-07-2007, 07:29 PM

Keeping your eyepieces capped and in your coat works. They are a bit warmer when you use them and don't fog up. Just return them to your pocket when not in use.

Simple

CoombellKid · #7 10-07-2007, 07:36 PM

Quote:

Originally Posted by rmcpb

Keeping your eyepieces capped and in your coat works. They are a bit warmer when you use them and don't fog up. Just return them to your pocket when not in use.

Simple

hmmmm.... a few XW's and the odd t5, thats get a lil weighty not to mention
realestate in the old pocket.

regards,CS

sheeny (Al) · #8 10-07-2007, 07:37 PM

I was going to suggest the low tech approach, but Rob has beat me to it!

The other methods also have their merits, but if you don't have them, keep your EPs in you pocket and rotate through different EPs as required. Of course it works best if you have more than 1 EP!

Al.

KG8 · #9 11-07-2007, 03:44 AM

keeping your EP's in you pocket is a good idea and if you have a heated strap to wrap around them once they go in the scope they will stay fog free. Otherwise they will cool down after a while and you will be back where you started from, or be constantly rotating EP's. Heaters and dew shields are the best solution. I don't consider hair driers as a good alternative, they work, but they can tend to bake stuff onto optical surfaces and your viewing will be interrupted by the need to blow the surfaces off. Much better to just never let the dew get there in the first place and a good heater system will see to that. If your serious about all night winter observing just bite the bullet, their not that expensive if you make most of them yourself.

huckabuck · #10 11-07-2007, 09:11 AM

i will sometimes use one of those chemical warmer things and attach it to the under side of the eyepiece i'm using with a rubber band

Gargoyle_Steve (Steve) · #11 11-07-2007, 08:25 PM

I've made all my own heater straps - I can keep 3 ep's "strapped" at a time, plus a 2 litre "Bulla" flip top icecream container became a heated ep storage box with some alfoil insulation and 4 (insulated) resistors in the bottom, I also have permanently mounted (but not permanently powered) front lens and viewing end heaters on my finderscope. All of these are powered by the same 12v battery that runs my cooling fan, Argo Navis, etc, via a 5 way power distribution box.

A little bit of simple wiring and a few choice resistors, etc - all up cost for the lot was maybe $20-25 including RCA plugs and sockets, black plastic box, resistors, heat shrink tube AND the 2 litres of yummy ice cream!!!

(Will attach images when I get a chance)

erick (Eric) · #12 11-07-2007, 09:48 PM

Caloundra? Heating??

ps. Happy Birthday Steve!! (too slack to post in the other thread!

ballaratdragons (Ken) · #13 11-07-2007, 10:00 PM

Quote:

Originally Posted by erick

ps. Happy Birthday Steve!! (too slack to post in the other thread!

KG8 · #14 11-07-2007, 11:05 PM

Quote:

Originally Posted by Gargoyle_Steve

plus a 2 litre "Bulla" flip top icescream container became a heated ep storage box

A heated EP box! Of course!! I already have the box with the EP's already in it. A narrow little aluminium job that began life as a cosmetics case ( thank you girls ) Now all I need to do is weave this spare nicrome wire I have back and forward under the foam.

Thanks steve'

erick (Eric) · #15 12-07-2007, 06:22 AM

I like to have my eyepieces in the racks on the scope. I'm thinking of making a heated cover that mounts over them. Let's see what I can design. Has to lift off easily or flip up to allow me to change eyepieces easily.

KG8 · #16 12-07-2007, 07:43 AM

Thats a better idea Erik. The EP's live in the tray so that is the natural place to heat them. Perhaps I could bore out the individual holes in the steel tray and press in aluminium sleaves, say 30 or 40mm long. Then I can fasion little rings of resistors to go around the sleaves. Slip them on in winter, off in summer.

rmcpb (Rob) · #17 12-07-2007, 08:17 AM

Or make a simple box around the tray with a flip top. Then add a few resistors in the bottom and so ends the problem of cold eyepieces in the pocket.

erick (Eric) · #18 12-07-2007, 08:28 AM

Yes, Rob, I have something like that in mind. But it'll take a bit of thinking/designing. I like my eyepieces to be uncapped and be able to change eyepieces with one hand. The box will also act as a dew shield on the uncapped eyepieces.

astro_nutt · #19 12-07-2007, 10:17 AM

I use a hotwater bottle wrapped in a tea-towel and sit my EP's on it..I found using a stubbie holder with the bottom cut out fitted over the front of my finder with a ziptie helps keep it clear.
Cheers!

KG8 · #20 12-07-2007, 08:00 PM

I guess it depends on where your EP's sit as to the best way to heat them. Mine are up high between the tripod legs, shielded by the mount above them. They can sit uncapped all night and not attract dew, though they tend to attract the odd finger mark, so I put a small illuminator over them so I don't fumble around in the dark.