[APML] To push Provia 400F or not (again!)

[Alen Koebel <akoebel@rogers.com>]

I know this has been talked to death here in the last
couple of years, but in all I've read I can't seem to
find what I need to help me make a decision. 

Last new moon I shot about half a roll of 400F through
a 6" f/5 Schmidt-Newtonian OTA (LXD55). Because I was
manually guiding I limited most of my exposures to 30
minutes. I also wanted to limit the sky fog density.
The last roll of 400F I shot at the same physical
site, through a 300-mm F/4.5 telephoto at f/5.6,
showed a lot of sky fog at 45-minutes. (Although
straight up I could shoot for nearly an hour to get a
similar sky density.) I figured 30 minutes at f/5
would show just a little less sky fog than 45-minutes
at f/5.6. Since sky brightness varies night to night,
I realize this may not be a valid calculation. 

So I'm wondering if I should push this latest roll
(e.g., by one stop). Will I get a "usable" image (for
scanning) of objects like NGC 6992, M31, M45 and NGC
1499 without pushing? (I also shot M8/M20 and M22 one
night, both also 30 minutes.) Would pushing hurt or
help my one and only concern, which is to get the
maximum data from the slide when I scan it (Minolta
Dimage Scan Dual III)? 
 
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