condensation spots

I used my 8" Dob in -20 degree C weather (about -5 degrees F)...very
cold, and when I brought it in, condensation was so bad I actually got
large water drops forming on my main mirror (not just the usual mist).
Once they dried up, they left behind small faint white spots
everywhere on the mirror.

How do I remove them? I'm sure I'll have to remove the mirror, but can
I just use a lens cleaning brush (like the lipstick-style Orion Ultra
Brush), or will I have to actually wash it? Thanks in advance.

Patrick wrote:
I used my 8" Dob in -20 degree C weather (about -5 degrees F)...very
cold, and when I brought it in, condensation was so bad I actually got
large water drops forming on my main mirror (not just the usual mist).
Once they dried up, they left behind small faint white spots
everywhere on the mirror.

How do I remove them? I'm sure I'll have to remove the mirror, but can
I just use a lens cleaning brush (like the lipstick-style Orion Ultra
Brush), or will I have to actually wash it? Thanks in advance.

Eventually, perhaps next autumn, you might consider washing your mirror.
Likely what you're seeing is re-distributed dirt that was already on the
mirror before the condensation formed. If it didn't affect you images
then, it likely won't affect your images now.
A mirror of good figure has to get almost unbelievably dirty to have any
noticable effect on image quality.
A year or two between washings is usually fine. When necessary, use
dishwashing detergent and water. Some people forego the detergent and
just use a blast from a garden hose. I like warm water and detergent. I
never touch the coated surface with anything, just soak it till the
grunge gets loose, then rinse it very well and leave to dry vertically.
You can reduce condensation by covering both ends of the tube before
bringing it indoors. Or by leaving it outdoors.

Happy Observing.
Etok


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Patrick wrote:
I used my 8" Dob in -20 degree C weather (about -5 degrees F)...very
cold, and when I brought it in, condensation was so bad I actually got
large water drops forming on my main mirror (not just the usual mist).
Once they dried up, they left behind small faint white spots
everywhere on the mirror.

How do I remove them? I'm sure I'll have to remove the mirror, but can
I just use a lens cleaning brush (like the lipstick-style Orion Ultra
Brush), or will I have to actually wash it? Thanks in advance.

Eventually, perhaps next autumn, you might consider washing your mirror.
Likely what you're seeing is re-distributed dirt that was already on the
mirror before the condensation formed. If it didn't affect you images
then, it likely won't affect your images now.
A mirror of good figure has to get almost unbelievably dirty to have any
noticable effect on image quality.
A year or two between washings is usually fine. When necessary, use
dishwashing detergent and water. Some people forego the detergent and
just use a blast from a garden hose. I like warm water and detergent. I
never touch the coated surface with anything, just soak it till the
grunge gets loose, then rinse it very well and leave to dry vertically.
You can reduce condensation by covering both ends of the tube before
bringing it indoors. Or by leaving it outdoors.

Happy Observing.
Etok


__________________________________________________ _____________________________
Posted Via Uncensored-News.Com - Accounts Starting At $6.95 - http://www.uncensored-news.com
The Worlds Uncensored News Source

Patrick wrote:
I used my 8" Dob in -20 degree C weather (about -5 degrees F)...very
cold, and when I brought it in, condensation was so bad I actually got
large water drops forming on my main mirror (not just the usual mist).
Once they dried up, they left behind small faint white spots
everywhere on the mirror.

How do I remove them? I'm sure I'll have to remove the mirror, but can
I just use a lens cleaning brush (like the lipstick-style Orion Ultra
Brush), or will I have to actually wash it? Thanks in advance.

Eventually, perhaps next autumn, you might consider washing your mirror.
Likely what you're seeing is re-distributed dirt that was already on the
mirror before the condensation formed. If it didn't affect you images
then, it likely won't affect your images now.
A mirror of good figure has to get almost unbelievably dirty to have any
noticable effect on image quality.
A year or two between washings is usually fine. When necessary, use
dishwashing detergent and water. Some people forego the detergent and
just use a blast from a garden hose. I like warm water and detergent. I
never touch the coated surface with anything, just soak it till the
grunge gets loose, then rinse it very well and leave to dry vertically.
You can reduce condensation by covering both ends of the tube before
bringing it indoors. Or by leaving it outdoors.

Happy Observing.
Etok


__________________________________________________ _____________________________
Posted Via Uncensored-News.Com - Accounts Starting At $6.95 - http://www.uncensored-news.com
The Worlds Uncensored News Source

Don't do anything until it's really dusty, a few water spots is not going to
affect anything. Once a year is probably about right if you keep the
dustcaps on when not in use.

I definitely wouldn't blast it with a water hose. I mix up a pint of 50%
isopropyl alchol, 50% distilled water, and a few drops of dishwashing
detergent. Pour it on the mirror and let it sit a while to loosen things
up. Swish the mixture around the mirror with cotton balls. Put no direct
pressure on the mirror, just use the cotton balls to move the liquid around.
Then rinse with distilled water and prop it up vertically to dry. You can
use a blow dryer to evaporate the stubborn drops that will bead up. You'll
never get perfection, some water spots will remain, but it won't matter at
the eyepiece.

Mirrors coatings are more delicate than eyepiece coatings, so don't rub.

Jim


"Patrick" wrote in message
om...
I used my 8" Dob in -20 degree C weather (about -5 degrees F)...very
cold, and when I brought it in, condensation was so bad I actually got
large water drops forming on my main mirror (not just the usual mist).
Once they dried up, they left behind small faint white spots
everywhere on the mirror.

How do I remove them? I'm sure I'll have to remove the mirror, but can
I just use a lens cleaning brush (like the lipstick-style Orion Ultra
Brush), or will I have to actually wash it? Thanks in advance.

Don't do anything until it's really dusty, a few water spots is not going to
affect anything. Once a year is probably about right if you keep the
dustcaps on when not in use.

I definitely wouldn't blast it with a water hose. I mix up a pint of 50%
isopropyl alchol, 50% distilled water, and a few drops of dishwashing
detergent. Pour it on the mirror and let it sit a while to loosen things
up. Swish the mixture around the mirror with cotton balls. Put no direct
pressure on the mirror, just use the cotton balls to move the liquid around.
Then rinse with distilled water and prop it up vertically to dry. You can
use a blow dryer to evaporate the stubborn drops that will bead up. You'll
never get perfection, some water spots will remain, but it won't matter at
the eyepiece.

Mirrors coatings are more delicate than eyepiece coatings, so don't rub.

Jim


"Patrick" wrote in message
om...
I used my 8" Dob in -20 degree C weather (about -5 degrees F)...very
cold, and when I brought it in, condensation was so bad I actually got
large water drops forming on my main mirror (not just the usual mist).
Once they dried up, they left behind small faint white spots
everywhere on the mirror.

How do I remove them? I'm sure I'll have to remove the mirror, but can
I just use a lens cleaning brush (like the lipstick-style Orion Ultra
Brush), or will I have to actually wash it? Thanks in advance.

Don't do anything until it's really dusty, a few water spots is not going to
affect anything. Once a year is probably about right if you keep the
dustcaps on when not in use.

I definitely wouldn't blast it with a water hose. I mix up a pint of 50%
isopropyl alchol, 50% distilled water, and a few drops of dishwashing
detergent. Pour it on the mirror and let it sit a while to loosen things
up. Swish the mixture around the mirror with cotton balls. Put no direct
pressure on the mirror, just use the cotton balls to move the liquid around.
Then rinse with distilled water and prop it up vertically to dry. You can
use a blow dryer to evaporate the stubborn drops that will bead up. You'll
never get perfection, some water spots will remain, but it won't matter at
the eyepiece.

Mirrors coatings are more delicate than eyepiece coatings, so don't rub.

Jim


"Patrick" wrote in message
om...
I used my 8" Dob in -20 degree C weather (about -5 degrees F)...very
cold, and when I brought it in, condensation was so bad I actually got
large water drops forming on my main mirror (not just the usual mist).
Once they dried up, they left behind small faint white spots
everywhere on the mirror.

How do I remove them? I'm sure I'll have to remove the mirror, but can
I just use a lens cleaning brush (like the lipstick-style Orion Ultra
Brush), or will I have to actually wash it? Thanks in advance.