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

["Chris Cook" <ccjd@ix.netcom.com>]

I've only pushed 400F once at +2 and found that the film had a strong red
shift if exposed to the sky fog limit.  It was difficult to remove during
processing.
My recent M101 shot is a straight exposure on 400F, no push:

http://www.abmedia.com/astro/current/m101-fs102.html

My plan is to only shoot this film straight or with a +1 push.

Chris

----------------------------------
Chris Cook
Astronomical & Nightscape Photography
www.abmedia.com/astro

-----Original Message-----
From: Jon Kolb <jkolb@datawest.net>
To: 'Discussion of Film Astrophotography' <astro-photo@seds.org>
Date: Saturday, May 31, 2003 5:50 PM
Subject: [APML] Short Provia 400F Exposures (was: Rho & M8M20)


>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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