[APML] Converting CCD Workflow to Film?

["Thomas W. Earle" <twade@bmi.net>]

As everyone is well aware of, we users film are at a big
disadvantage with longer focal length telescopes/lenses while trying
to capture comets along with their field of deep sky objects.  I'm
trying to determine if it would be worth trying some CCD techniques
in order to capture the deep sky objects in the field of view, along
with the detail in the comet tail (i.e. you must guide on the
comet).  The need for guiding on the comet is where the problem
lies.  For example, if by some miracle the sky clears tomorrow
(5/11), I'm going to try and capture it with my Pentax 67 300 mm
F/4.0 and my Takahashi FSQ-106N.  Unfortunately, with the comet
moving at 5.0"/minute, I'm only allowed 3 minutes 30 seconds and
around 2 minutes, respectively, before the stars start to elongate.
Even with fast film (i.e. NPZ 800 or Provia 400F pushed 1 stop),
there is no way to capture the deep sky object too, much less the
fainter tail of the comet.  In the following link, the author
describes how he takes several shorter exposures, maintaining
pinpoint stars, and combines them later:

http://www.ewellobservatory.com/ccd/comet.cfm

Would this even remotely work for film?  I understand that film is
not linear; however, could this technique still produce acceptable
results (i.e. adding frames to bring out the fainter deep sky
objects and tail).  Any thoughts would be greatly appreciated.

Wade


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