[APML] Transit exposure help

["Jeff Ball" <jeffball@astro-photography.com>]

Hello,
I am looking for some help on exposure times for transit.  I will
attempt a couple of imaging approaches.  My plan is to first capture the
transit at sunrise over the ocean without filter with Traveler and 6x7
with Provia 100.  I know I am limiting my dynamic range with slide film,
but I have my rationale.  First reason is that I don't really have much
experience with many print films of late.  I also desire a very
grain-free image.  I have one exposure of the sun over the ocean that I
can use for a benchmark.  It is with the Canon 10D and 70-200mm f2.8 IS
lens.  The exposure on that shot was at f27 for 1/10 second at ISO 100.
The sun is just shy of being burnt out.  There were a few nice horizon
layers of thin clouds.  My f ratio on the Traveler is fixed at f6, and
my film is fixed at 100, so my only adjustment is exposure time.  I am
initially calculating that my digital exposure would translate into a 5
stop translation where I would use an exposure time of 1/500 to equal
the digital exposure settings.  I am limited to 1/1000 exposure time
with the Pentax 67.  I am guessing that I am probably wrong in my
calculations.  Any help would be greatly appreciated.  I realize that
the conditions could vary greatly on the morning of the transit.  I may
have to resort to some Velvia 50 or similar to avoid overexposure on the
solar disk.  It is my assumption that I will pick up Venus on the disk
at 600mm focal length without a filter if the exposure is properly
performed without overexposing.  I do have a Minolta spot meter and also
plan on setting up the Canon with 200mm and 2x extender as a metering
device.  I hope to do some pre-transit practice on Monday morning.
After the first few minutes of shooting on the horizon, I will then
resort to filtered exposures.  Thanks again for any help.

Best regards,
Jeff Ball
www.astro-photography.com
 

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