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You wrote:
>Thanks to Joe Cali, Gary Becker, and Veikko Makela for their kind
responses. I
>will forward a paraphrase of these answers to the original requester. I
did
>have one question, however: both Joe and Gary seemed to agree that
increasing
>the magnification (e.g., from unity to 7x) on an extended source like a
lunar
>halo should decrease its contrast. However, my experience in observing
faint,
>extended deep-sky objects is that increasing magnification (up to a
certain
>point) will generally actually INCREASE the contrast of the faint source
>against the dark-sky background. Do observers of bright light phenomena
(such
>as lunar halos and sundogs) generally find that this conventional
"deep-sky
>wisdom" is actually reversed?? Again, thanks for forwarding any comments
to me
>directly, as well as to the 'meteoptic' list!
Yes, I believed that "deep-sky wisdom" is reversed in case of halos. If
you
try to observe a faint halo (around sun or moon) and like to increase
contrast to get better picture of halo you have to decrease magnification.
One device to do that is convex mirror. Convex mirror is not very good
with
lunar halos (because those are often very faint) but works very well with
daytime halos.
>Clear skies (or hazy as you prefer... ;>),
>Lew Gramer
>owner-meteorobs_at_latrade.com
>
Jarmo Moilanen
jarmom_at_netppl.fi
http://www.netppl.fi/~jarmom/
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