[APML] Short Provia 400F Exposures (was: Rho & M8M20)

["Jon Kolb" <jkolb@datawest.net>]

In a previous post, I mentioned that only 15 minutes at f/4 will record
quite a bit on 400F with a one stop push.  Here's a manually guided
sample shot to show what can be done.  I was doing some example shots
with this lens because I was considering selling it, but now that I
finally focused it with a KEF and I see what it can do, I think I'll
keep it around.  This shot is actually blown out a bit and is clipped
very slightly at the high end, but as an example of the film's ability
on a short exposure I think it's OK.
http://home.datawest.net/jkolb/m8-m20_300mm.htm

The 400F also is good at recording star fields.  Here's one I did at
f/7.9 for only 15 minutes just to see how tight I could get the stars
(since we know that chrome films will tend to blow out stars on long
exposures), and it's also a one stop push.  I think the star colors look
more natural in this shot than in longer exposures I've done in the
past, and M11 obviously has better resolution than it would with blown
out stars.
http://home.datawest.net/jkolb/m11_tmb152.htm

For comparison, here's a much longer shot, 90 minutes, with a one stop
push again.  The stars are somewhat bloated, but it's also cropped and
enlarged from the original.
http://home.datawest.net/jkolb/m45_tmb152.htm

I have never tried pushing this (or any) film 2 stops, but I might do
another round of test shots just to see what happens.  Right now it's
just nice to get a clear night for a change.  For a one stop push, I'm
using the following exposure times for nebulous targets...
f/4: 15 - 30 minutes
f/6.4: 45 - 60 minutes
f/7.9: 60 - 90 minutes

Sincerely,
Jon Kolb
Adventures in Astrophotography
http://home.datawest.net/jkolb/
jkolb@datawest.net



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