[rollei_list] Re: looks like ... Agfa Scala
- From: Carlos Manuel Freaza <cmfreaza@xxxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Mon, 30 May 2005 12:39:49 -0300 (ART)
Mark, the characteristic curves is linked to the
process used to develop the film. Kodaks says." A
characteristic curve is a graph of the relationship
between the amount of exposure given a film and it's
corresponding density after processing. (Kodak)".In
other words the difference that you can see between
the APX 100 and the Scala in the Agfa technical sheet
is originated because they were made considering two
processes different completely, negative process for
the APX 100 and positive process for the Scala, more
the push and pull process for the other curves in the
graphs for the Scala. The curve for the Scala would
change if processed like a negative film.
In the other hand, the Spectral Sensitivity shows the
film behavior without the development process
influence, and then it shows that the APX 100 and the
Scala are identical for the way they capture the light
reflected from the subject, it coincides with the
historic data saying the Scala is based on the APX
100, a different thing is the film processing and the
characteristic curve after the process.
It would be very interesting to compare the Scala and
APX 100 characteristic curve after to process both
film using Kodak D 76, in example.-
All the best
Carlos
--- Mark Rabiner <mark@xxxxxxxxxxxxxxxx> escribió:
> On 5/30/05 5:26 AM, "Carlos Manuel Freaza"
> <cmfreaza@xxxxxxxxxxxx> typed:
>
> > Ruben:
> > I'm afraid that your post has a serious
> > omission, you don't consider the process and the
> > chemicals used for the process, the secret for the
> > special Agfa Scala reversal process like for the
> > Rollei R3 pushed film process are the chemicals.
> > However, for the Scala film, its relationship with
> the
> > APX 100 is a historic data and is a technical
> data,
> > you can compare the spectral sensivity for the APX
> 100
> > and the Scala reading the Agfa film technical data
> > sheet, they are identical:
> >=20
> >
>
http://www.agfaphoto.com/en-GB/photography/professional-photography/films=
> /down
> > loads/F-PF-E4en.pdf
> >=20
> > (It's necessary to scroll the page)
> >=20
> > You can imagine the chemical process influence for
> the
> > grain if you consider that for "normal" films,
> there
> > are developers giving ultra fine grain, fine
> grain,
> > medium grain, etc., and in fact, the Scala film
> also
> > can be developed using a "normal" developer
> producing
> > excellent negs=A1
> >=20
> > All the best
> > Carlos=20
> >=20
> >=20
> >=20
> I don't know why they would show those spectral
> sensitively on the top of
> each report like it was a big deal. So your lips are
> more light with one
> film than the other I've never heard of anyone
> picking a film because of
> it's spectral sensitively.
> Look at the characteristic curve! That shows you
> more what a film is going
> to make images like. The scala is of course reversed
> and of course like a
> transparency film way more steep and vertical
> meaning much more gamma and
> contrasty, a shorter distance from left to right
> than a normally processed
> black and white film.
> We are comparing normally processed black and white
> film against
> transplanted film folks! Even if it's black and
> white slides instead of
> color it's still slides! Reversal processing! Scala
> film is going to
> resemble Kodachrome a lot more than it's going to
> resemble a black and whit=
> e
> negative. And I'm talking reversing the direction of
> the curve so they'd
> maybe match up.
> A negitive we of course don't look at.
> We don't look at normally processed black and white
> film.
> We look at the prints we make from that film.
> And that makes a whole different curve in the end.
> In Ansel's photo series he says a black and white
> glossy print has a 50 to
> one luminance ration. A matt print 20 to one. But a
> slide, projected I thin=
> k
> is 200 to one.
> Slides you expose for the highlights and you loose
> the shadows real fast.
> Negitives you can still expose for the highlights
> and your not going to
> loose your shadows anywhere near as fast. Your tonal
> range is much wider
> than slides.
> Saying Scala resembles Agfapan 100 seems real way
> off crazy to me. Maybe I'=
> m
> missing something.
>
>
> Mark Rabiner
> Photography
> Portland Oregon
> http://rabinergroup.com/
>
>
>
>
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