ASTRO:dew proplem with new STL-11000

I put about 6 hours on the unit getting acquainted with its operation
before taking it to my dark site just south of Blueknob, PA. Unit
dewed up the first 10 minute exposure! SBIG manual says the desiccant
plug should last a year! I have recharged the desiccant, but SBIG
does not provide any extra o-rings - how cheap can they be. Between
the dew and the computer crashing the control program every third
attempt, I did not any good images.

Robert Price

Robert,

what a shame that you did not have better luck for your "first light". Such
an expensive toy should work without any user intervention...

Stefan

"Robert Price" schrieb im Newsbeitrag
...
I put about 6 hours on the unit getting acquainted with its operation
before taking it to my dark site just south of Blueknob, PA. Unit
dewed up the first 10 minute exposure! SBIG manual says the desiccant
plug should last a year! I have recharged the desiccant, but SBIG
does not provide any extra o-rings - how cheap can they be. Between
the dew and the computer crashing the control program every third
attempt, I did not any good images.

Robert Price

Robert Price wrote:
I put about 6 hours on the unit getting acquainted with its operation
before taking it to my dark site just south of Blueknob, PA. Unit
dewed up the first 10 minute exposure! SBIG manual says the desiccant
plug should last a year! I have recharged the desiccant, but SBIG
does not provide any extra o-rings - how cheap can they be. Between
the dew and the computer crashing the control program every third
attempt, I did not any good images.

Robert Price


What happened to the ring? Mine is now 6 years old and going strong.
When cooking the desiccant be sure to remove the ring. I forgot that
once but got lucky, it was still stuck to the side of the chamber so
hadn't seen the oven after all. After cooking it takes a good 24 hours
to dry the air. More if you didn't cover the opening while the plug was
removed. I use a piece of electrical tape but even masking tape should do.

New cameras can have the plug work loose and let in humidity but that's
rare. I'm wondering if the problem is due to frost inside or outside
the chamber. I have a problem in winter when the dew point is virtually
the same as ambient. I can't cool much or the outside of the window
frosts. It appears almost identical to yours. Heat tape around the
camera has solved that problem. Never had it in summer however, no
matter how high the humidity. Still I wonder which side of the window
had the problem. I've never had frost inside the window but then I
always bake it each fall during a full moon period. Other users I know
have gone as long as 3 years without a problem. I just consider it
preventive maintenance. Since it was still dry when I baked it, and I
keep the hole covered, it is ready to go once cooled enough to reinstall
without burning fingers or O ring.

I never checked but I'd expect the ring to be standard that a good
hardware store should stock if yours needs replacement.

One final thought, is yours a new or old camera? the first ones made
don't have the heaters to warm the window that new ones do. Those
prevent the outside condensation problem, at least in summer.

Also were you using water cooling? This can so cool the rest of the
camera to create this problem if you cool using too cold of water. I
don't use water as the camera works fine at -20C which I can reach in
summer any night. Even -15C works fine when I've accidently used it.
Haven't tried warmer but if darks are matched as to time and temperature
getting really cold isn't very important.

Looks like the scope can handle the large chip so you'll be set once you
get the frosting under control.

Rick

Rick,

Camera is new, images were taken at -20 degrees C. 10 mimutes each
LRGB. Darks but no flats. Nothing happened to the ring, but from my
work as an engineer, it is good practice to replace the o-ring with a
new one every change, at least other equipment I worked with
recommended this.

Robert

On Sun, 16 Aug 2009 20:30:19 -0500, Rick Johnson
wrote:

Robert Price wrote:
I put about 6 hours on the unit getting acquainted with its operation
before taking it to my dark site just south of Blueknob, PA. Unit
dewed up the first 10 minute exposure! SBIG manual says the desiccant
plug should last a year! I have recharged the desiccant, but SBIG
does not provide any extra o-rings - how cheap can they be. Between
the dew and the computer crashing the control program every third
attempt, I did not any good images.

Robert Price


What happened to the ring? Mine is now 6 years old and going strong.
When cooking the desiccant be sure to remove the ring. I forgot that
once but got lucky, it was still stuck to the side of the chamber so
hadn't seen the oven after all. After cooking it takes a good 24 hours
to dry the air. More if you didn't cover the opening while the plug was
removed. I use a piece of electrical tape but even masking tape should do.

New cameras can have the plug work loose and let in humidity but that's
rare. I'm wondering if the problem is due to frost inside or outside
the chamber. I have a problem in winter when the dew point is virtually
the same as ambient. I can't cool much or the outside of the window
frosts. It appears almost identical to yours. Heat tape around the
camera has solved that problem. Never had it in summer however, no
matter how high the humidity. Still I wonder which side of the window
had the problem. I've never had frost inside the window but then I
always bake it each fall during a full moon period. Other users I know
have gone as long as 3 years without a problem. I just consider it
preventive maintenance. Since it was still dry when I baked it, and I
keep the hole covered, it is ready to go once cooled enough to reinstall
without burning fingers or O ring.

I never checked but I'd expect the ring to be standard that a good
hardware store should stock if yours needs replacement.

One final thought, is yours a new or old camera? the first ones made
don't have the heaters to warm the window that new ones do. Those
prevent the outside condensation problem, at least in summer.

Also were you using water cooling? This can so cool the rest of the
camera to create this problem if you cool using too cold of water. I
don't use water as the camera works fine at -20C which I can reach in
summer any night. Even -15C works fine when I've accidently used it.
Haven't tried warmer but if darks are matched as to time and temperature
getting really cold isn't very important.

Looks like the scope can handle the large chip so you'll be set once you
get the frosting under control.

Rick

There's little pressure on the O-ring. I've never heard of one going
bad other than when one was melted in the oven.

If baking didn't solve the problem check the camera immediately after
seeing the problem to be sure which side of the window has the frost.
If inside your desiccant may be bad, though I never heard of this. If
ourside you may need to either warm the camera body or drop the cooling.
It's humid here since I'm on a lake but I've never had that problem in
summer, only winter. Know those using water cooling have when they used
ice water in high humidity as that cooled the camera body too much.
Never heard of that with air cooling however.

Those with the problem in summer with water cooling say if they cool the
camera in steps, starting well before they plan to observe the humidity
inside collects on places other than the window first and tends to stay
there rather than spread as cooling is increased.

SBIG is good about phone calls so if you can't solve it otherwise give
them a call.

Rick


Robert Price wrote:
Rick,

Camera is new, images were taken at -20 degrees C. 10 mimutes each
LRGB. Darks but no flats. Nothing happened to the ring, but from my
work as an engineer, it is good practice to replace the o-ring with a
new one every change, at least other equipment I worked with
recommended this.

Robert

On Sun, 16 Aug 2009 20:30:19 -0500, Rick Johnson
wrote:

Robert Price wrote:
I put about 6 hours on the unit getting acquainted with its operation
before taking it to my dark site just south of Blueknob, PA. Unit
dewed up the first 10 minute exposure! SBIG manual says the desiccant
plug should last a year! I have recharged the desiccant, but SBIG
does not provide any extra o-rings - how cheap can they be. Between
the dew and the computer crashing the control program every third
attempt, I did not any good images.

Robert Price


What happened to the ring? Mine is now 6 years old and going strong.
When cooking the desiccant be sure to remove the ring. I forgot that
once but got lucky, it was still stuck to the side of the chamber so
hadn't seen the oven after all. After cooking it takes a good 24 hours
to dry the air. More if you didn't cover the opening while the plug was
removed. I use a piece of electrical tape but even masking tape should do.

New cameras can have the plug work loose and let in humidity but that's
rare. I'm wondering if the problem is due to frost inside or outside
the chamber. I have a problem in winter when the dew point is virtually
the same as ambient. I can't cool much or the outside of the window
frosts. It appears almost identical to yours. Heat tape around the
camera has solved that problem. Never had it in summer however, no
matter how high the humidity. Still I wonder which side of the window
had the problem. I've never had frost inside the window but then I
always bake it each fall during a full moon period. Other users I know
have gone as long as 3 years without a problem. I just consider it
preventive maintenance. Since it was still dry when I baked it, and I
keep the hole covered, it is ready to go once cooled enough to reinstall
without burning fingers or O ring.

I never checked but I'd expect the ring to be standard that a good
hardware store should stock if yours needs replacement.

One final thought, is yours a new or old camera? the first ones made
don't have the heaters to warm the window that new ones do. Those
prevent the outside condensation problem, at least in summer.

Also were you using water cooling? This can so cool the rest of the
camera to create this problem if you cool using too cold of water. I
don't use water as the camera works fine at -20C which I can reach in
summer any night. Even -15C works fine when I've accidently used it.
Haven't tried warmer but if darks are matched as to time and temperature
getting really cold isn't very important.

Looks like the scope can handle the large chip so you'll be set once you
get the frosting under control.

Rick

"Robert Price" wrote in message
...
Rick,

Camera is new, images were taken at -20 degrees C. 10 mimutes each
LRGB. Darks but no flats. Nothing happened to the ring, but from my
work as an engineer, it is good practice to replace the o-ring with a
new one every change, at least other equipment I worked with
recommended this.



----I'm an engineer too Robert, electrical to be exact: microelectronics is
my field.

I've given up on SBIG except for guiding: they cost more typically and don't
work as well as their competition in my experience. I've tried the security
in numbers approach when I first got going, and that's why I bought their
products. But they kept falling short of what I considered to be normal
expectations and quite frankly I decided that someone else could enjoy that
experience instead of me so I sold everything except my two ST7s I use as
guiders. Cooling doesn't matter in my guider and so frosting is not a
problem

Among the problems besides frosting: dead camera, degrading cooling,
degrading read noise. poor cooling in all cases.

I got tired of lugging water pumps, chillers, hoses and so on to Fremont
Peak so I could maintain a -15C operating temperature in the summer. It just
became too burdensome. So I switched to FLI... Had great results with my
first product from them (Dream Machine) and I found later that they were
very interested in ideas I had for how to make a better mousetrap. It's been
a good relationship for all parties ever since from my perspective.

SBIG isn't bad, you can certainly do a lot worse, but I found what I liked
better and an outfit that was responsive to my concerns and could see the
value of my ideas.
rdc