MFHult_at_nothydrologistnot.com wrote:
>
> On Fri, 30 Jan 2004 12:55:30 -0500, Jean-David Beyer <j_at_d.b> wrote in
> message <401A9A92.6000704_at_d.b>:
>
> >MFHult_at_nothydrologistnot.com wrote:
> > > On Fri, 30 Jan 2004 08:03:56 -0500, Jean-David Beyer <j_at_d.b> wrote in
> > > message <401A563C.7020702_at_d.b>:
> > >
> > >
> > >> David Nebenzahl wrote:
> > >
> > > exposure and film latitude, prompting the question:
> > >
> > >
> > >>> Why do color reversal films have less latitude than negative
> > >>> films?
> > >>
> > >
> > >> So one might say that reversal films have the same latitude as
> > >> negative films (possibly more), but the effects of incorrect
> > >> exposure are
> > >
> > > different.
> > >
> > >
> > > Are you saying that Dmax-Dmin is the same for reversal and negative
> > > films?
> > >
> >It depends on what you mean. If you mean for measuring with a
> >densitometer, using the exposures usually used, the Dmax - Dmin of
> >slides is considerably higher (2.4 perhaps) than for negatives (1.6 to
> >1.8 perhaps). But negatives _can_ go much higher in density than that if
> >you like (mostly you would not like, because they are too difficult to
> >print).
> >
> >But if you go to heroic measures, you can use a greater density range in
> >the negatives. What you do is print darker than usual, and arrange the
> >lighting so that the illumination on the print (but not the surrounding
> >mat, frame, and wall) is much higher than customarily used. This will
> >permit you to see detail in the shadows that you would not see in normal
> >conditions. And the highlights are pleasingly bright. But no one, and no
> >gallery that I know of do this (I am not an expert in galleries, only a
> >couple of local ones and the Museum of Modern Art in NYC, the
> >Metropolitain Museum of Art also in NYC, The Weston Gallery in Carmel,
> >and The Art Institute of Chicago.)
> >
> >You can read all this in "The Theory Of The Photographic Process", third
> >edition, by Mees and James, Chapter 22 (chapter by C.N.Nelson).
>
> Good suggestion. I re-read most of those 35 pages and refreshed my
> understanding of the topics.
>
> But am still struck by my long-standing notion shared by others that
> negative films in general can record a greater Dmax-Dmin than reversal
> films and that this range can be usefully exploited in making photographs.
Dmax/Dmin actually refers to density. What you seem to be referring to
is not density range (Dmax-Dmin), but the tolerance for exposure (log
exposure or subject luminance ranges.) This is where b&w film shines,
since you not only have greater latitude to begin with, but can adjust
development to record a greater subject luminance range than "normal."
But your Dmin/Dmax is going to remain the same.
> I realize now that I have never actually measured shadow density on slide
> films with a densitometer -- indeed essentially all my densitometry has
> been on negative films because the intended purpose for slides is/was for
> viewing and their suitability for that purposes is best accomplished by
> viewing, not measurement.
Well, transparency film is somewhat more versatile than that. Just about
all color reproductions in magazines, advertising, books, calendars,
etc, are from transparency films. That's what professionals shoot. And
while a good drum scan can pretty much capture all the highlight and
shadow detail (Dynamic Range = 4.0), scans need to be matched to the
reproduction requirements -- in other words measurement comes in handy there.
