Re: [APML] E200 and Provia 400F pushing

[Wei-Hao Wang <whwang@gmail.com>]

Hi Nicola,

In short, I would not suggest pushing 2 for Provia 400F.  It's too grainy.

I compared the S/N of E200 and Provia 400F, pushing 2 and no push.
In mid-tones, pushing 2 helps to improve S/N slightly on both slides. 
This is because the increase in density compensates the increase in 
grainuity.  On the other hand, it's a slightly different story in the 
shadow.  While pushing has no effect on the S/N of the shadows of 
E200, it decreases the S/N of 400F.  

When we process an image in computers, S/N of the image is the 
key factor that determines how much we can do.  Personally I pay
more attention to the shadow regions.  (The mid-tone has high S/N
anyway.)  From this point of view, not pushing 400F is better because 
it maintains the S/N in the shadow regions.  As long as we have 
good scanners, we can bring out the details in the shadows digitally
and we don't need to push it.  Pushing actually demages our ability
of processing 400F.

Although pushing 400F decreases its S/N, I still tend to push it.
This is because I hope to not only process the image digitally, but 
also to view the slides through a slide projector.  Pushing makes
the objects brighter and increases the contrast.  Usually I choose
to push 1 instead of 2.  This is a compromise between the S/N and
the contrast on the slide.

Hope this helps.

Wei-Hao

-- 
________________________________________________________________
Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

Address:                       
2680 Woodlawn Drive         Personal Website:
Honolulu, HI 96822             http://www.ifa.hawaii.edu/~wang
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