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

["Steve Lindsey" <stevelindsey@earthlink.net>]

Thanks Jon for the explanations and beautiful examples as good reference
info for this film.  My M8M20 shot seems identical to yours if I stretch and
adjust the dark point some more.  I found that the infinity setting on the
lens I used (non-ED f4.5) seemed like tight focus already without backing
off though I didn't check it.  I almost check it but just got lazy and I
guess I lucked out!

Steve


> 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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