Surely the phrases 'extremely wide exposure latitude of XP2' and 'No
matter which film speed is chosen, standard C41 processing is
recommended.' confirms that the exposure lattitude of the neg is wider
than paper so over or under exposing a single frame by a stop or two can
be corrected at the printing stage with no noticeable effect as the
final print will always be 18% grey by default.
The only effect would be the change in characteristic of the grain etc,
but this would be no different for a single frame to a whole film. This
is very different to slide film etc where the processing needs to be
different for different ratings.
I didnt believe in the idea at first, but you are confirming it, not
disproving it!
Rob Brigham
-----Original Message-----
From: Shel Belinkoff [mailto:[EMAIL PROTECTED]]
Sent: 21 May 2001 15:54
To: [EMAIL PROTECTED]
Subject: Re: Chromogenic B&W Film
[EMAIL PROTECTED] wrote:
>
> While I haven't shot chromogenic B&W since 1987, I distinctly remember
more
> than one review citing the frame-by-frame flexibility, at least for
Ilford
> XP-1. I can't recall "what happens" to the +2 or -2 ISO frames; they
> werern't rendered less usable, just different. I don't believe it was
about
> grain.Contrast, perhaps?
>
> What do the chromogenic filmmakers' websites say? Is this claim
currently > being made?
Excerpted from the Ilford site:
XP2 SUPER is a chromogenic film. This means that
the dyes which make up the image are formed
during development rather than being present in
the film or added later.
The extremely wide exposure latitude of XP2
SUPER is the result of the unique relationship
between exposure and grain in chromogenic films.
The best balance of sharpness and grain is
obtained when XP2 SUPER is exposed at
EI 400/27. However, down-rated or overexposed
XP2 SUPER negatives have finer grain, the
opposite of that expected and obtained with
conventional films. Up-rated or underexposed XP2
SUPER negatives have only a slight loss in quality.
EXPOSURE RATING
XP2 SUPER film has a speed rating of
ISO 400/27° (400ASA, 27DIN, EI 400/27) to
daylight. The ISO speed rating was measured
using standard C41 processing. Although rated at
ISO 400/27°, XP2 SUPER can be exposed over the
range EI 50/18-800/30. When higher speed is
needed, XP2 SUPER can be rated at up to
EI 800/30. For finer grain, when speed is less
important, rate the film at EI 200/24, although for
finest grain it can be rated as low as EI 50/18 if
required.
CHOOSING THE RIGHT FILM SPEED FOR
THE JOB
Best overall quality EI 400/27
Finer grain (with easy printing) EI 200/24
Finest grain (but with denser negatives) EI 50/18
Note
No matter which film speed is chosen, standard
C41 processing is recommended.
It should be noted that nowhere in the data sheet could i find
anything that said exposing a roll using different film speeds was
acceptable or good practice. Of course, you can go to the web site
and read the entire PDF file yourself.
http://www.ilford.com/html/us_english/bw.html
--
Shel Belinkoff
mailto:[EMAIL PROTECTED]
"... there is no point in pressing the shutter
unless you are making some caustic comment
on the incongruities of life" - Phillip Jones Griffiths
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