Folks,
My prime focus shots from the October
new moon (using my usual rig, site, and
exposure times) are way past the sky-fog
limit. Was this enhanced sky glow
from the recent solar activity, or
enhanced film sensitivity because
the temperature dipped down to 25F
during the imaging session.
I've been doing prime focus astrophotography
for less than a year and so have no
experience with film in the cold, or
with significant sky glow. I've
settled on Elite Chrome 200 for most
of my shots, and routinely run 45-60 min
exposures through my f/4.5 refractor at
a site in the Oregon desert.
During the October new moon, I returned to
this desert site and ran some exposure of
targets fairly high in the sky (M31, M44,
IC1396), using my usual equipment, film,
and exposure times. The film came back
with far brighter sky background - perhaps
even unusable - than usual. I'm talking
about the sort of difference one would see
from 1-2 stop overexposure of slide film
in a daylight picture.
Two things were different from my usual
conditions: 1) There was intense recent
solar flare activity. 2) For the first
time, the temperature dipped below 32F
while using this film.
What's the experience with E-200 in the
cold? Does the sensitivity increase by
one to two f-stops going from 40F to 25F?
If weather permit I'll do the experiment
now that the cold weather is here and the solar
activity has subsided. But I'd like to
know other's experience with E-200 in the
cold, or with deep sky pictures during the
recent solar activity.
Oh - there was no aurora visible from
the site during the evening I was
imaging. My log notes say that the
sky was not "terribly dark" that night,
but my visual calibration of sky glow is
not accurate - I'm not in the habit of
recording the highest magnitude stars
visible. Does this practice, in fact,
give one a sufficient gauge to adjust
exposures by?
Thanks in advance.
Todd
My prime focus shots from the October
new moon (using my usual rig, site, and
exposure times) are way past the sky-fog
limit. Was this enhanced sky glow
from the recent solar activity, or
enhanced film sensitivity because
the temperature dipped down to 25F
during the imaging session.
I've been doing prime focus astrophotography
for less than a year and so have no
experience with film in the cold, or
with significant sky glow. I've
settled on Elite Chrome 200 for most
of my shots, and routinely run 45-60 min
exposures through my f/4.5 refractor at
a site in the Oregon desert.
During the October new moon, I returned to
this desert site and ran some exposure of
targets fairly high in the sky (M31, M44,
IC1396), using my usual equipment, film,
and exposure times. The film came back
with far brighter sky background - perhaps
even unusable - than usual. I'm talking
about the sort of difference one would see
from 1-2 stop overexposure of slide film
in a daylight picture.
Two things were different from my usual
conditions: 1) There was intense recent
solar flare activity. 2) For the first
time, the temperature dipped below 32F
while using this film.
What's the experience with E-200 in the
cold? Does the sensitivity increase by
one to two f-stops going from 40F to 25F?
If weather permit I'll do the experiment
now that the cold weather is here and the solar
activity has subsided. But I'd like to
know other's experience with E-200 in the
cold, or with deep sky pictures during the
recent solar activity.
Oh - there was no aurora visible from
the site during the evening I was
imaging. My log notes say that the
sky was not "terribly dark" that night,
but my visual calibration of sky glow is
not accurate - I'm not in the habit of
recording the highest magnitude stars
visible. Does this practice, in fact,
give one a sufficient gauge to adjust
exposures by?
Thanks in advance.
Todd
