Re: Newt/Mak-Newt and body heat

I have noticed, during both the past two Mars oppositions, that with a
Maksutov-Cassegrain, when someone stands within 10 yards in front of the scope,
that the image does degrade noticeably. When I ask them to move, the image does
improve. But the only time I thought I saw the same effect with my own body was
when the telescope was pointed nearly straight overhead. This make sense. But
there should be no effect cause by body heat on calm night. If the wind is
blowing enough to carry body heat to the front of the telescope, then it's more
likely that wind currents around your body is causing the effect, not your body
heat. If you're radiating that much body heat, then you're not wearing enough
covering on these cold winter nights.

Sincerely,
--- Dave Nakamoto
--
----------------------------------------------------------------------
Pinprick holes in a colorless sky
Let inspired figures of light pass by
The Mighty Light of ten thousand suns
Challenges infinity, and is soon gone

david.nakamoto@xxxxxxxxxxx


"Mark D" <mmd49@xxxxxxxxx> wrote in message
news:7445-43FE6585-183@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I'd like to know what your experiences have been with body heat
affecting your newtonian or mak-newtonian telescopes. I have found that
during very cold nights heat radiating from my body to the front of a
MCT can degrade images. I repeatedly moved away from the scope and
always returned to find the image a little steadier, then turning
noticeably unsteady. This happens when observing at high powers. Was it
my imagination or have others experienced this? What have you done to
resolve the problem?
Dan
======================================

Hi Dan, Either you own a very small MCT for this to happen, or meant
to say MNT, or Newt?

I've never heard of this being an issue with a larger MCT, but I suppose
it isn't impossible, and certainly would be possible with a Newt-Mak
Newt due to the observer's proximity to the front of the scope.

The warm clothes you wear should offer a buffer, but naturally, the
hands, face-head can become objects that radiate heat into the optical
path. Just holding a hand beneath any Scope's objective, or the front
of a Newt Tube on any night will show this effect as scintillation.

I once read a story about a large professional Observatory's main mirror
needing some minor adjusting (Mt. Wilson, or?), and once they got in
there to adjust the large metal wedge blocks that support the massive
Primary mirror, body heat ruined the Scope's ability to come to
equilibrium for the entire evening.

I wouldn't suspect this being quite as much a long term detriment to a
smaller amateur instrument, but yes, rising heat can certainly ruin an
image in short order.

Other items which are commonly known to virtaully all amateurs, is not
viewing over houses, or vehicles during an obseerving-imaging session,
nor setting a Scope up on Concrete Patios. Even in the summer, these
objects store mucho heat from during the day, that can play havoc hours
after ole Sol has set.
mark



.

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