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Science Forum Index » Astro - Amateur Forum » An unlikely pairing.... and condensation problems!
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Message |
| Steve & Lizzie |
 Posted: Fri Feb 02, 2007 8:19 pm |
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Guest
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Hello to all
I've had my Explorer 130P since last May. Before this time I'd only ever
dreamed of owning a scope so as a rank amateur I've had a lot of really
valuable help from this group - thank you.
It has taken me time to learn that instant action and the short term "fixes"
that this brings is really second fiddle to results achieved with proper
preparation (cool down time, planning etc). I now feel I'm a bit more
structured in my approach.
I live in Liverpool UK and clear skies are something of a rarity at this
time of year, however today showed great promise so I prepared my kit - I
wasn't disappointed! As the moon is full I planned to do a lot of lunar
observing, I was also keen to view Saturn again and hoped to be able to see
these two together at the same time as they converged.
Obviously general viewing was marred somewhat by the moonlight, however I
still had a fine old time. Saturn looked great - I've just got a new 4mm EP
and found that not having to use my X3 Barlow/10mm combo gave a slightly
crisper image. My teenage daughter is visiting me at the moment and this was
the first time she had chance to share the views - she was blown away!
As the pair moved closer I fully expected to loose site of Saturn as it
became obscured by the moons brightness - how wrong I was. It was my turn to
be blown away when I found that I could get these two in the same field of
view with perfect clarity (at least for a rookie) using my 10mm EP.
I'm sure most of you are relatively familiar with such a sight, but I just
couldn't get enough of it! Brilliant!
Now that I've come back down to earth, it's time for me to beg your advice
again. I found tonight that my scope got really wet with condensation. My
EP's were constantly steaming up - this I managed by gentle wiping with a
lens cloth. But I also found that my secondary mirror steamed up quite a
bit! I'm sure its bad practice but the only way round this was to use the
cloth again very carefully on the mirror! Is this just something that I have
to learn to live with or is there another way round it?
I'd be very grateful if anyone can share their tips or rules of thumb with
regards to this.
Many thanks
Steve |
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| Ben |
| Posted: Sat Feb 03, 2007 7:17 am |
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Guest
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On Feb 2, 6:19 pm, "Steve & Lizzie" <steveandliz...@blueyonder.co.uk>
wrote:
Quote: Hello to all
I've had my Explorer 130P since last May. Before this time I'd only ever
dreamed of owning a scope so as a rank amateur I've had a lot of really
valuable help from this group - thank you.
It has taken me time to learn that instant action and the short term "fixes"
that this brings is really second fiddle to results achieved with proper
preparation (cool down time, planning etc). I now feel I'm a bit more
structured in my approach.
I live in Liverpool UK and clear skies are something of a rarity at this
time of year, however today showed great promise so I prepared my kit - I
wasn't disappointed! As the moon is full I planned to do a lot of lunar
observing, I was also keen to view Saturn again and hoped to be able to see
these two together at the same time as they converged.
Obviously general viewing was marred somewhat by the moonlight, however I
still had a fine old time. Saturn looked great - I've just got a new 4mm EP
and found that not having to use my X3 Barlow/10mm combo gave a slightly
crisper image. My teenage daughter is visiting me at the moment and this was
the first time she had chance to share the views - she was blown away!
As the pair moved closer I fully expected to loose site of Saturn as it
became obscured by the moons brightness - how wrong I was. It was my turn to
be blown away when I found that I could get these two in the same field of
view with perfect clarity (at least for a rookie) using my 10mm EP.
I'm sure most of you are relatively familiar with such a sight, but I just
couldn't get enough of it! Brilliant!
Now that I've come back down to earth, it's time for me to beg your advice
again. I found tonight that my scope got really wet with condensation. My
EP's were constantly steaming up - this I managed by gentle wiping with a
lens cloth. But I also found that my secondary mirror steamed up quite a
bit! I'm sure its bad practice but the only way round this was to use the
cloth again very carefully on the mirror! Is this just something that I have
to learn to live with or is there another way round it?
I'd be very grateful if anyone can share their tips or rules of thumb with
regards to this.
Many thanks
Steve
Steve & Lizzie
1. Never use a cloth on glass. A cloth will pick tiny pieces
of grit that will give you scratches.
2. Never ever use a cloth on an aluminum coated mirror. It will
give you "sleeks", which don't detract from you image very much
but I still don't like having them. Use a cotton wad or (better)
a camel hair artists brush. Wash the brush occasionally.
3. Any tinted or anodized in black will begin to collect dew first
because it gives up heat first. Pays to monitor the dark items.
As far as eyepieces go, you can keep them warmed up by
keeping them in your coat pocket. A screw type lens case is
handy because you can appropriate one case for two EP's. The
case will protect the oculars from lint in your pocket.
I bought a sporting vest to keep EP's and it works very well.
If your secondary is dewing consider fashioning an extension
dewshield or purchasing one. I bought a shield for a 12" SCT
for my 10" Newt and have never had a dewed secondary (yet).
Hope this helps,
Ben T
90.126 N 35.539 |
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| W. H. Greer |
| Posted: Sun Feb 04, 2007 4:19 pm |
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Guest
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On Sat, 03 Feb 2007 00:19:09 GMT, "Steve & Lizzie"
<steveandlizzie@blueyonder.co.uk> wrote:
Quote: Now that I've come back down to earth, it's time for me to beg your advice
again. I found tonight that my scope got really wet with condensation. My
EP's were constantly steaming up - this I managed by gentle wiping with a
lens cloth. But I also found that my secondary mirror steamed up quite a
bit! I'm sure its bad practice but the only way round this was to use the
cloth again very carefully on the mirror! Is this just something that I have
to learn to live with or is there another way round it?
Ben provided a good reply. Nevertheless, I'll provide a bit of
reinforcement, etc.
One of the best (and most expensive) solutions for the eyepiece
problem is to provide gentle heat around the eyepiece. A dew removal
(heater) system is an effective, but costly solution.
A far more cost effective approach would be to wave your hand over the
eyepiece. The air flow should eventually clear the eyepiece. This
approach is less effective than the first one; but it costs nothing!
Of at least equal importance are preventive measures: Take great care
of how you exhale and the direction in which your exhaled breath goes.
You want to avoid breathing on your optics. Your breath will most
likely be warmer than the surrounding air and have a much greater
concentration of moisture. The moisture in your breath will instantly
condense on your cold optical surfaces -- if you allow it to reach
those surfaces.
Wiping the eyepiece isn't too terribly bad assuming the eyepiece and
the cloth are completely free from abrasive particles; but it's still
a risky operation. I prefer the wave of the hand approach (or in
extreme situations a dew heater). Eyepieces cost money to replace;
and money is not always easily acquired.
Next on the agenda is your mirror: Telescope mirrors are
first-surface mirrors. They're *far* more susceptible to sleeks, etc.
than your typical bathroom mirror. You should *never* wipe dew or
frost from a telescope mirror. Damage is practically guaranteed to
occur!
If airflow fails to clear the mirror in the field, then your only
reasonable option is to end your observations with that telescope! I
would cover such a mirror prior to bringing it inside. After it has
warmed sufficiently (this can take half a day or so depending on
temperature differentials) I would uncover it and allow any lingering
moisture to *completely* evaporate prior to re-covering it until the
next observing session.
A tube extension, as suggested by Ben, is an effective preventive
measure against dewed telescope mirrors. In addition, be careful with
your breath. Don't allow it to enter your telescope tube!
Personally, I *far* prefer preventive measures over dealing with wet
optical surfaces and the inevitable water spots that will follow.
One final piece of advice: NEVER clean your telescope mirrors until
you've thoroughly researched the topic and know exactly what you're
doing! My own telescope optics get cleaned less frequently than once
a year. In same cases it's been far less frequently! I prefer to
take preventive measures that minimize the risk of getting the optics
dirty.
--
Bill
Celestial Journeys
http://cejour.blogspot.com |
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