Cool down times in eyepieces...

Since getting my new Pentax XWs I believe I've started to notice a pattern.
They need cool down time much like my telescope does. If the scope is
cooled down enough, I can take my eyepieces warm out of the house outside
and put my ortho's in without a problem. They just work. However, when I
try this with my Pentax's I get that blurry feeling again, similar to mirror
cool down issues. If I wait about 10 or 20 minutes (depending on how big
the difference in temperature is) everything seems fine again. Have others
seen this? It's not a big deal as I now just put my eyepieces out to cool
with everything else. My scope seems to cool down in around a 1/2 hour and
that seems more than enough for the eyepieces too. Just curious.

Thanks,

Mike.

--
To reply, remove the "z" if one appears in my address
"Mike Fitterman" wrote in message
...
Since getting my new Pentax XWs I believe I've started to notice a
pattern.
They need cool down time much like my telescope does. If the scope is
cooled down enough, I can take my eyepieces warm out of the house
outside
and put my ortho's in without a problem. They just work. However, when
I
try this with my Pentax's I get that blurry feeling again, similar to
mirror
cool down issues. If I wait about 10 or 20 minutes (depending on how
big
the difference in temperature is) everything seems fine again. Have
others
seen this? It's not a big deal as I now just put my eyepieces out to
cool
with everything else. My scope seems to cool down in around a 1/2 hour
and
that seems more than enough for the eyepieces too. Just curious.

Thanks,

Mike.

Hi, Mike!

This has been my experience with (some of) my larger eyepieces. I never
really noticed it (because I always set everything outside at the same
time, and it all sits out there waiting while the scope is coming to
thermal equilibrium) until one evening when I was just testing a couple
eyepieces, and left my big eyepiece case inside the house. During the
test, I changed my original plan, and decided to try a few other
eyepieces, and went inside and brought out another and then another, etc.
And it took me a few minutes to figure out why the crappy performance of
each one I brought out, compared to the original ones. It was the
relatively large thermal mass of the eyepieces (Panoptics and Naglers),
and the fairly large delta between the inside and outside temperatures.
It didn't take them long to come to thermal equilibrium - quite a bit less
than most scopes - but the effects, were easily seen.

I'm not sure to what degree, or even if, this would be a problem with
simpler, smaller eyepiece designs, but it was noticeable with several of
my longer focal length Panoptics and Naglers... Because of the way I
normally set up, I haven't tried this with any of my shorter focal length,
smaller thermal mass eyepieces, so I can't say, based on experience, if
the same would be the case with them... But now I do bear in mind these
results, and make doubly sure my eyepieces go out at the same time as the
scope...

I'd be interested in the experiences of others, too...

Jan

--
To reply, remove the "z" if one appears in my address
"Mike Fitterman" wrote in message
...
Since getting my new Pentax XWs I believe I've started to notice a
pattern.
They need cool down time much like my telescope does. If the scope is
cooled down enough, I can take my eyepieces warm out of the house
outside
and put my ortho's in without a problem. They just work. However, when
I
try this with my Pentax's I get that blurry feeling again, similar to
mirror
cool down issues. If I wait about 10 or 20 minutes (depending on how
big
the difference in temperature is) everything seems fine again. Have
others
seen this? It's not a big deal as I now just put my eyepieces out to
cool
with everything else. My scope seems to cool down in around a 1/2 hour
and
that seems more than enough for the eyepieces too. Just curious.

Thanks,

Mike.

Hi, Mike!

This has been my experience with (some of) my larger eyepieces. I never
really noticed it (because I always set everything outside at the same
time, and it all sits out there waiting while the scope is coming to
thermal equilibrium) until one evening when I was just testing a couple
eyepieces, and left my big eyepiece case inside the house. During the
test, I changed my original plan, and decided to try a few other
eyepieces, and went inside and brought out another and then another, etc.
And it took me a few minutes to figure out why the crappy performance of
each one I brought out, compared to the original ones. It was the
relatively large thermal mass of the eyepieces (Panoptics and Naglers),
and the fairly large delta between the inside and outside temperatures.
It didn't take them long to come to thermal equilibrium - quite a bit less
than most scopes - but the effects, were easily seen.

I'm not sure to what degree, or even if, this would be a problem with
simpler, smaller eyepiece designs, but it was noticeable with several of
my longer focal length Panoptics and Naglers... Because of the way I
normally set up, I haven't tried this with any of my shorter focal length,
smaller thermal mass eyepieces, so I can't say, based on experience, if
the same would be the case with them... But now I do bear in mind these
results, and make doubly sure my eyepieces go out at the same time as the
scope...

I'd be interested in the experiences of others, too...

Jan

"Mike Fitterman" wrote in message .. .
Since getting my new Pentax XWs I believe I've started to notice a pattern.
They need cool down time much like my telescope does. If the scope is
cooled down enough, I can take my eyepieces warm out of the house outside
and put my ortho's in without a problem. They just work. However, when I
try this with my Pentax's I get that blurry feeling again, similar to mirror
cool down issues. If I wait about 10 or 20 minutes (depending on how big
the difference in temperature is) everything seems fine again. Have others
seen this? It's not a big deal as I now just put my eyepieces out to cool
with everything else. My scope seems to cool down in around a 1/2 hour and
that seems more than enough for the eyepieces too. Just curious.

Thanks,

Mike.

I've seen people put a warm 2" diagonal on a cold scope and think the
scope had yet to cool down. I guess any glass optic of sufficient mass
needs some kind of noticeable cool-down time.
-Rich

"Mike Fitterman" wrote in message .. .
Since getting my new Pentax XWs I believe I've started to notice a pattern.
They need cool down time much like my telescope does. If the scope is
cooled down enough, I can take my eyepieces warm out of the house outside
and put my ortho's in without a problem. They just work. However, when I
try this with my Pentax's I get that blurry feeling again, similar to mirror
cool down issues. If I wait about 10 or 20 minutes (depending on how big
the difference in temperature is) everything seems fine again. Have others
seen this? It's not a big deal as I now just put my eyepieces out to cool
with everything else. My scope seems to cool down in around a 1/2 hour and
that seems more than enough for the eyepieces too. Just curious.

Thanks,

Mike.

I've seen people put a warm 2" diagonal on a cold scope and think the
scope had yet to cool down. I guess any glass optic of sufficient mass
needs some kind of noticeable cool-down time.
-Rich