Nailer follows this list and is evidently a graduate
chemist with an excellent knowledge of photo chemistry.
  The term low contrast developer generally means that it
takes that developer longer to obtain the same contrast as a
more active developer. There are specialized developers for
extreme contrast conditions. For instance lighographic
developers. These are extremely active developers with large
amounts of restrainer in them. They tend to go from not
developing a halide crystal to full development over a very
short range of exposure. There are also very low contrast
developers, for instance POTA or Technidol, which are
designed to produce low contrast from inherently high
contrast materials. They are slow, and will not achieve
"normal" contrast even with extended time, but are produce a
"normal" curve shape and are more like "normal" developers
than a lith developer. D-76 and D-23 have both been called
low contrast developers but are simply slow to build
contrast in comparison to developers like Kodak D-60a, or
D-61, once commonly used for photo-finishing and press work.
  I have no idea of what Adam's experience was with
specific developers but some of them don't seem to make
sense. D-23 can be a "compensating" developer when used at
high dilutions. Compensating means that a developer creates
a shoulder on the characteristic curve, or, in other words,
lowers the contrast of highlights. At normal strength D-23
should not do this.
  Blocking of highlights means that there is no detail in
them. That can happen because there is no detail in the
negative or because the negative contains highlights which
are beyond the ability of the printing paper to reproduce
them. The latter problem can be solved by burning in because
the detail is there. Blocking on negatives was a problem in
the distant past but modern films have very great
overexposure latitude and can record highlights much beyond
what can be printed simutaneously with normal mid-tones.
  Kodak has published curves for a few films done with
different developers. It seem to me that HC-110 does produce
a slight shoulder when compared to developers like T-Max. I
don't think this accounts for your experience.
  I don't have Grant Haist's book at hand so I can't look
up the authentic D-76H. However, A Borax developer with
characteristics very similar to D-76 can be made up without
the Hydroquinone. At the relatively low pH of D-76 the
Hydroquinone is virtually inactive as a developing agent. It
probably has a regenerating effect on the Metol. The
so-called superadditive effect is not present because the
Metol only version produces just about the same densitys in
about the same time as the M-H version. The amount of Metol
is increased for reasons I don't fully understand.
  I rather think that extreme dilutions of any developer
will produce distorted tone rendition. Over a wide range its
possible to vary the overall contrast of negatives by
varying the development time. The exposure must be varied
also to maintain a constant range of density, but in
general, the shape of the curve will not be much affected.
To a great degree varying negative contrast and varying
paper contrast, by choice of grade or filter, will produce
identical results although the _shape_ of the paper
characteristic tends to change more than film.
  Remember that the range of brightness which can be
reproduced on a reflection print is only a fraction of what
can be recorded on film or what is in many original scenes.
Another important factor when deciding on contrast is the
perception of the eye. The eye expects to see approximately
normal contrast in mid-tones and is not too sensitive to
clipping of shadows or highlights. Bright highlights,
generally from specular reflections, don't have much detail
to begin with. Unless they are presented as large areas of
no detail, most viewers will not be disturbed. If contrast
is compressed so that a wide brightness range scene can be
reproduced on paper the resulting image will look flat and
unnatural to the eye. About the only way around this is
burning and dodging, which, if done carefully, will result
in greater detail in selected shadows and highlights while
maintaning a relatively normal gray scale.
  I will add only that there are no magic developers. There
are only a few developing agents in common use and those are
the ones that have survived a century of competition.
Excellent developers for most B&W uses can be made with
Metol and Hydroquinone or the more modern Phenidone and
Ascorbic acid. Color developers must react with the color
couplers to produce dye so other developing agents are found
in them.
  My standard developer is D-76 mostly diluted 1:1. It has
been reliable and long lived and works with most films.

  By compensating do you mean a developer which will
favor a more full development in less exposed and a less
full development in more exposed areas of the film?
  D23 I suppose could be thought of as compensating.
Most consider it a low contrast developer. FX-1, Beutler's,
Ethol TEC, and Rodinal are more thought of as being
compensating. Characteristic of those three is their
high ph and very dilute nature.
  D23 may make a good low contrast compensating
developer. Now and then I mix up an 8 - 80 grams D23,
1 - 10 grams at a time. That goes into 500 ml of solution.
The result is 1/2 liter of an 8 - 80 D23 1:3. That developes
one 120 roll of film.
  I've recently decided I should give 1:7 and 1:15 dilutions
a try. At those dilutions, in 500 ml of solution, there would be
0.5 - 5 and 0.25 - 2.5 grams respectively. A  metol - sulfite
developer with low contrast and compensating charater
should result.

  Back to that sulfite ph matter. The range of ph given
by manufacturers and other sources is quite great. Many
give a range within a ph of 9 to 10.5. IIRC, at least three give
a specific ph AND range for photo grade sulfite.
  My point is this. As users of sulfite we should not assume
from purchase to purchase we have the same stuff in
hand. We all know how shifts in ph will affect the
activity of a developer. Dan

 
   
 
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