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"Print So Fine" paper developer



 
 
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Old February 13th 06, 02:31 AM posted to rec.photo.darkroom
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Default "Print So Fine" paper developer


"Digitaltruth" wrote in
message
oups.com...
Nicholas Lindan has written to me and will be posting the
response I
sent him, but the claim we make is supported by subjective
analysis of
the print. We strive to post accurate information on our
web site and
all product descriptions are designed to help people find
what they are
looking for. Unlike a lot of other companies in the
market,
Digitaltruth Photo is run by photographers.

Personally, I have used a lot of print developers and
based on my own
experience if I was looking for a warm-tone image with
excellent
gradation, then Print-So-Fine would be my choice. Its not
a fast
developer - typically taking a minute more than a standard
developer -
so its not for everyone, but I would recommend it to
anyone who wants
better contrast control. The image appears slowly so it is
easier to
pull the paper out of the developer before the highlights
lose their
sparkle.

I agree with Richard Knoppow's post, and given that
sensitometry is
complex I prefer to judge things with my own eye. A print
is usually
judged by people who look at it and not by scientific
analysis;
however, we do have people making sensitometric tests and
will publish
the data as soon as it can be properly assessed. I can
assure you that
there is no apparent visible loss of density reported by
the various
people who have made subjective analyses of the prints, so
even if the
sensitometry shows a technical reduction in density this
does not
invalidate the experience of actual users. I'd love to
publish jpegs on
our web site, but there is no way to show the subtlety of
the effect on
a monitor.

--Jon Mided

Digitaltruth Photo
http://www.digitaltruth.com


I did not mean to give the impression that sensitometry
is complex. The principles are fairly simple. Controlling
the variables so that the measurement is valid requires some
care but not beyond what a careful darkroom worker can do.
For serious work it is necessary to have a real
densitometer. They are rather expensive new but used ones
are available at rather low prices because they have been
displaced by the shift to digital imaging. The densitometer,
as its name implies, measures the density of the image after
development. There are two types of densitometer, one for
transmission, another type for reflection. Some
densitometers are equipped to make both kinds of
measurement.
To make the test exposures one needs some method of
controlling the relative exposures accurately. Simply
photogaphing a flat surface with a camera is usually not
good enough because neither shutters or f/stops are
sufficiently accurate. However, step wedges and reflection
step tablets are readily available. These are offered in
both calibrated and un-calibrated versions. The only
difference is that the calibrated ones are individually
measured with a NIST certified densitometer and correction
factors are supplied. These are necessary for very accurate
work but ane not required for simple experimental
measurements to find the curves of film or paper or
measuring approximate exposure index or the effect of
different developers or development time. Such wedges are
avaialable from Stouffer at
http://www.stouffer.net/Stoufferhome1.htm where they are
fully described. The wedges can be used by contact printing
or enlarging.
A reflection step wedge is useful for calibrating a
reflection densitometer but it can also be used for direct
visual comparison. The eye is very good at matching relative
brightness of adjacent areas. So, one can get a pretty good
measurement of print density by laying the step tablet on
the print and matching the visual density of the area of
interest.
In serious scientific sensitometery its necessary to
controll a lot of factors that are not so significant where
one simply wants to compare printing papers or developers or
films. "Real" sensitometery must take into account:
The color temperature of the exposing source
The diffusion of the source compared to the method of
illumination to be used for the actual results, that is, it
must take into account the Callier factor.
It must take into account the effect of reciprocity failure.
That is, there is a difference between step exposures made
by holding the time of exposure constant and varying the
intensity, and those made by constant intensity and variable
time of exposure.
Development methods must be such as to be highly
reproducible. For instance, in making film speed
measurements a special insulated tank (like a Thermos
bottle) is used and special methods of agitation are used.
Again, this degree of control in not necessary for the
kind of determination most of us want but one should be
aware of all the variables and try to contoll them the best
one can.
Now, as a minimum for experimentation I would suggest a
reflection step tablet. One can photograph this and print
the negative and then compare the tablet visually to the
print. This simple procedure can tell you a lot about the
tone rendition of the system.
Beware that in prints the paper surface or texture makes
a lot of difference. The highest contrast and widest range
of brightness is gotten from glossy paper. Surface textures
reduce Dmax and contrast because they scatter light. A
highly textured surface will also suppress image detail
(sometimes desirable) so textured papers should not be used
for overall testing. However, the method described above
will also tell you what the losses from the texturing are.


--
---
Richard Knoppow
Los Angeles, CA, USA




 




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