Fogging optics/ winter observing.

Folks;
This is a crosspost from the Televue Yahoo group that I thought would
be of help to you folks also...
-Steve
--------------------------
I do a fair amount of photography during the winter, in the snow. My
camera lenses are constantly fogging internally. I also travel to
Hawaii and do photography during rain storms. In both cases, drying
out optics is very much a part of my routine. At night, in the snow, I
put the lenses by the heater, without caps and out of cases. In the
tropics I put the lenses and camera (without caps, etc.) in the Sun
for hours.

For astronomy during the winter, I NEVER put my lens caps on, put the
scope caps on, or put stuff in cases until they have had a chance to
dry out in a warm house overnight. Plastic cases are much worse for
trapping in moisture.

Anyone who does not leave their caps off for many hours after coming
in from winter observing, when the temp is below 45 deg., is asking
for trouble.

Got internal fogging. Put the item in the Sun or near a wall heater
for a few hours.

In the last 20 years in the business I have seen many, many times more
damage done to optics by mold than done by abuse. Time after time I
see guys (yes, never women,who are obsessed w/ keeping caps on their
binoculars, telescopes, and eyepieces, bringing in optics that are
damaged by mold. They are also usually obsessed w/ never cleaning
their optics.

Mold damages all optics over time if you don't take care to dry them
out and clean them. This goes for digital cameras, camera lenses,
binoculars, telescopes, eyepieces, etc.

Also, no astronomical telescopes or eyepieces are sealed. They ALL
breath a bit. They have to. If they did not, condensation would be
much worse. They only way sealed optics work is if the internal optics
have been purged w/ nitrogen.

I hope this helps.

Steve D. White
TeleVue Optics N. American Rep.


www.televue.com

So when will we see eyepieces purged with nitrogen?

Roger Persson
(Love my nitrogen-filled Fujinon 7x50 binocular)

Steve D. White wrote:
....
Also, no astronomical telescopes or eyepieces are sealed. They ALL
breath a bit. They have to. If they did not, condensation would be
much worse. They only way sealed optics work is if the internal
optics
have been purged w/ nitrogen.

I hope this helps.

Steve D. White
TeleVue Optics N. American Rep.


www.televue.com

Roger Persson wrote:
So when will we see eyepieces purged with nitrogen?

For a nominal fee, you can send me your eyepiece case. I will purge
not only the airspaces but the glass and metal of your eyepieces with
a special mixture, approximately 80/20 nitrogen/oxygen (with a few
impurities), and return the case to you.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

I think the eyepieces must be designed for this? Refraction index,
gaskets?

Roger Persson

Yes Brian! A year ago I would have signed up for your special service!!!!!
Learning....

Doink!


"Brian Tung" wrote in message
...
Roger Persson wrote:
So when will we see eyepieces purged with nitrogen?

For a nominal fee, you can send me your eyepiece case. I will purge
not only the airspaces but the glass and metal of your eyepieces with
a special mixture, approximately 80/20 nitrogen/oxygen (with a few
impurities), and return the case to you.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt