Fun shot. Best way to avoid star trails is planning. I have little comet
experience but plenty with astro-landscapes. You should use the maximum
shutter speed that still avoid star trails. How long depends on how picky you
are. Pertinent variables include focal length, latitude, focal length,
declination, sensor format size. I use the sharp star app within photo-pils.
Typically require an ISO of 3200 or so then. I usually take a test shot at
higher ISO to be sure is focused and I like the comp. Too noisy you say?
Stack about 16 ish images. I use Sequater as it is quite easy. That fixes the
stars but the comet will be a mess. You would have to experiment quickly to
get longest SS for the comet to look good and make a composite. If you want
is all done by software I know DSS (Deep Sky Stacker) has a comet mode but you
have to put a pointer at the center of the comet with each sub. That will
reduce noise about 4 stops and keep the stars aligned and the comet just
deliciously perfect. DSS is very powerful but has a steep learning curve.
Sequater processes much faster and it takes 15 minutes to learn. I think the
software for either are free.
Curiously HHHR (hand held high res) mode on Oly cams WILL stack stars on a
tripod if and only if the sky is dark enough (usually class II Bortle or so and
the sky predominates in the image---or will stack the foreground. That won't
fix the comet though. I can find a tutorial of HHHR use in astro if you like.
I don't know why Oly won't provide a firmware option to use with starry sky AF
to limit the stack to the sky. That would be a powerful feature.
I realize these suggestions will not fix your current image but might be useful
for the next.
Sharp stars or bust, Mike
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