Re: [APML] Push Processing (was Scanning slides)

["D. Kodama" <kodama@alumni.caltech.edu>]

If you look at the Kodak datasheet on E200:

  http://www.kodak.com/global/en/professional/support/techPubs/e28/e28.jhtml

you can see that the official "gain" of the film is:

   +1  =>  320
   +2  =>  640
   +3  =>  800

But as mentioned earlier, the main benefit to pushing is not so much the
speed as the lightness of the background for scanning.

It's true that push processing will increase the grain, but even at +3
push, I think it's far less grainy than an equivalent negative shot
because far less post scan contrast enhancement is necessary for the
already contrasty positive than the rather flat negative.  The contrasty
positive does make high contrast objects saturate, but in general, for
subtle nebulosity, it's a benefit.

My normal procedure is to go with a +2 push with E200.  In southern
California, I get a light background in 45 minutes at f/4.  In the dark
skies of Namibia, I went with 60 minutes

> Alan,
>
> When you get the E200 or Provia400 push processed with long exposures
> (many
> minutes to hours) you will probably see half the push effect.  That means
> ask for +2 and the film will be about +1 stop actual.  Ask for +1 and it
> will be about +1/2.  What I was trying to convey was th.at you can not
> expect
> that +1 processing will allow 1 stop less exposure for the same astro
> picture.  Both these slide films have significant reciprocity but are
> still
> picking up light with 4 hours exposure.
>
> See also Jerry Lodriguss' response that you don't want black sky.  The
> trick
> is to get your exposure to the point where the sky is not dark black, but
> rather some dark gray/blue so you can scan it.  Once the sky fog is
> reached,
> more sky light detracts from the range of light sensitivity (contrast) and
> begins to wash-out the picture.  Getting the right exposure of the sky
> with
> slide film is one of the secrets to getting good pictures out of the
> slide.
> Too dark and it won't scan, too light and it's washed out.
>
> Hope this helps,
> Don
>
>
>> I do have one question regarding your comments below. You say that your
>> tests indicate that +2 nets a +1 for AP purposes. If I was to ask for a
>> push with my film, does that mean I need to ask for a +2 to get a +1?
>> Or that it doesn't matter
>>
>> Thanks,
>> Alan
>
>
>
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>
>

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