Phil,
Following is some info extracted from my manual on Pd/Pt printing.
Sensitometry
The apparent values in a photographic print or negative can be quite
different from the actual physical densities. Part of this is due to
the fact that any value will influence the appearance of another value
it is next to. Another consideration is that a particular value may
feel right for the context of a particular image.
Knowing the density of a spot on a negative or print is utterly
useless. So too is any line, curve, or number. These terms may be used
to talk tough, but that's not a photograph. A d-logE curve will provide
no information as to how the photograph is seen. A densitometer will
provide a useless number at great expense.
Getting an absolute black means nothing. Claims are made that
such-and-such is better because it provides a blacker black (or "it's
D-max is better"). Black is not black. Even the deepest shadow, even
in the middle of the night, is not as black as black, especially with
the platinum-palladium process. Let it be known right here that if a
blacker black is desired, then one should use the gelatine silver
process. Different papers, as well as variations in chemistry, will
provide different blacks. It would NOT be wise to select a paper (or
worse discard a paper) based only on its blackest value (or D-max).
And, surprise, the blackest black in the print will never be the
blackest possible. (Note: If not surprised, a good amount of printing
experience must be at hand.)
Zones like blacks are also misunderstood. A zone is a zone. Not a
particular value, a zone is a range of values. By definition a zone has
been set to the range of values between the relative end points of a one
stop range. The exact value is selected by the photographer for that
particular print. A zone may differ in the next print or with the next
subject. Zones become useful in understanding relative increments of
exposure and development.
Might as well continue with a description of whites. With the platinum
palladium process, many papers are available for selection. Each paper
will have its own white. Optical brightening agents may alter the paper
white. The platinum-palladium process will not produce a white as
brilliant as a gelatine silver print. If that's what is needed, print
in gelatine silver. It is thought that zone X is paper white. This is
not the case, especially with pure palladium. Zones IX,X, and XI may be
distinguished and still not be paper white. The upper values are
extremely important to a print. Finding and using the proper materials
can make all the difference.
All one needs to know about the sensitometric qualities of film and
materials can be had by making, fine tuning, and studying the Matrix
described in the next section. Notes of the original scene at hand, the
Matrix of negatives, and the Matrix of prints all laid out upon the
table provide a wealth of information. From these one can see the
smallest amount of density that will just separate a tone from the
darkest density in the print ("speed point", zone I). It can also be
seen at what density in the film the print will stop exhibiting texture
("contrast", zone VIII) or just remain as plain as paper base ("upper
limit"). If the print captures the quality that the photographer feels
then it must be right. So too, the negative may be read as to
containing such feeling.
To see a photograph, the photographer must know what the print looks
like, and what kind of negative produced that print, and what kind of
seeing lead to producing that negative. This only comes through
experience and with much practice.
Simultaneous Exposure and Development Control
To expand one's creative ability to the maximum, one must have a
disciplined mind and a disciplined procedure. Disciplining one's mind
takes much practice. A disciplined procedure for the simultaneous
control of density and contrast follows.
A matrix of exposure and development times will be made.
Each piece of photographic equipment has unique qualities and may
produce different results. So, use the equipment that is normally used
immutably. The rough version of the matrix will require 12 sheets of
film or three rolls (12 frames/roll) of film.
Note: These amounts are chosen to conserve film. I strongly suggest
starting with these amounts. More film may be used later to repeat and
fine tune the matrix.
Note: It is important that each sheet film holder is numbered. It will
also be helpful if each sheet has a corresponding number exposed onto
it.
Select a subject typical of one's work that satisfies all of the
following:
Neither the subject nor lighting moves.
Zones 0,I,II,VI,VII,VIII, & IX are represented in large areas.
Note: Zones III,IV,V, & X may be present.
Note: It may help to place some large panels of uniform value into the
scene.
Note: The best location for finding all these zones will be where the
subject is both in direct sun and deep shadow.
Note: If one's typical source of light is artificial, then use that
light instead of the sun.
The camera is fixed upon a tripod.
Carefully visualize how the print should look, and take notes.
Note: This is a very important step.
Carefully meter the subject:
Note: The light meter should be chromatically corrected for film
sensitivity, such as the one available from Zone VI Studios Inc. If
not, make sure that all readings are taken from neutral gray, white, or
black cards.
Spot-meter from as close to the film location as possible.
It is most important to find Zone VIII.
Make sure Zones 0,I,II,VI,VII,VIII, & XI are represented and
recorded.
Make a sketch and show all of the metered values. Calculate the
exposure:
Use one's presently known film speed.
Note: Do not worry if correct at this point; true film speed will be
found by evaluating the fine tuned matrix.
Use the Zone VIII reading to calculate the exposure.
Note: This is very important.
Note: Remember that meters read everything as ZONE V. Thus, the meter
reading of Zone VIII will provide an exposure setting three stops
different from the actual setting required. (Take the meter setting and
add three stops more exposure.)
Expose film for the calculated exposure and for one stop above and
below the metered exposure.
For sheet film:
Expose 3 sheets at the calculated setting
Expose 3 sheets at one stop over the calculated setting.
Expose 3 sheets at one stop under the calculated setting.
For roll film:
Expose frames 1-3 at the calculated setting
Expose frames 4-6 at one stop over the calculated setting.
Expose frames 7-9 at one stop under the calculated setting.
Do not expose frames 10-12.
Repeat the above for the other two rolls.
Note: Complete all the exposures as quickly as possible so that the
chance of any variation is minimized.
Note: It is important to note exposure data for each sheet or frame.
Note: Fine tuning will be based on previous results.
Develop film with developer normally used for the time normally used
and for times 25% shorter and 25% longer.
Note: If negatives are being produced for the platinum-palladium
process for the first time, normal development should be approximated at
about twice the time for silver printing.
Note: It is strongly suggested that, for platinum-palladium printing,
the film be developed in Kodak HC-110. This is the only developer that
will have enough strength for the plus developments.
Note: Always keep development times between 3 and 6 minutes (no less
than 3 to insure good uniform development, and no longer than 6 to
reduce base fog). Double or half the concentration of the developer
(and correspondently half or double the time of development) to stay
within this 3-6 minute range.
Note: For "normal" development of Kodak Tri-X 4164 film (using a film
speed index of ASA 200), try a concentration of 64 ml Kodak HC-110
developer with 936 ml water (64 ml/l) for 5¼ minutes. Kodak HC-110
works well at concentrations as high as 512 ml/l and as low as 16 ml/l.
Note: Agitation is continuous for the entire development. This insures
repeatable results.
Note: Development is affected by temperature. Temperature must be
constant and standardized. This means that the temperature not be
allowed to change during development. Also, the same temperature must
be used whenever developing. For all time! (and at any time of year.)
Or, one must re-calibrate the matrix. The best solution to the
temperature factor is to use a temperature compensating timer such as
the one Zone VI Studios Inc. manufactures.
For sheet film:
Develop one of each of the 3 exposures plus one of the unexposed (4
sheets) for the "normal" time.
Develop one of each of the 3 exposures plus one of the unexposed (4
sheets) for 25% more than the "normal" time.
Develop one of each of the 3 exposures plus one of the unexposed (4
sheets) for 25% less than the "normal" time.
For roll film:
Develop one roll for the "normal" time.
Develop one roll for 25% more than the "normal" time.
Develop one roll for 25% less than the "normal" time.
Note: Keep all other processing conditions constant.
Note: Fine tuning will be based on previous results.
For each development time, determine the exposure to print "maximum"
black with the unexposed film.
Note: Use the printing method and materials that are typical, because
results will vary for differing methods and materials.
Note: The "maximum" black is not the maximum density possible with the
materials. An exposure in which it is thought that there is a
distinction between "maximum" black and maximum black is close to the
proper exposure.
Note: Do not be surprised if printing times increase for the plus
developments. This is most likely due to an increase in base fog.
Print all of the exposed films, for each film development time, at the
exposures found by the above step.
Note: Be consistent.
Evaluate all prints when dry.
Make a decision as to which print best represents the subject as
visualized before exposure. Interpellate between selected exposures and
development times if necessary.
Zones 0,I, & II will provide information on film speed.
Zones VII,VIII, & IX will provide information on film development.
Note: This is a very important step.
Repeat the matrix to fine tune and add more information.
I have found that fine tuning of the Matrix is only necessary to half
stop increments. It is easy to interpolate quarter stop differences and
difficult to be more accurate than that with any equipment and
processing. I have found it useful to expand the development axis from
minus one to plus four (and again, ½ stop increments is fine.)
If one makes mature and honest decisions, then one will arrive at the
best possible statement of the original, objective interaction of
subject and photographer. But keep in mind that when creating each
photograph, one must make slight variations to the exposure,
development, and printing established above because each interaction
with a subject will differ.
Normalization of Matrix
Now that you have a Matrix, what if you change equipment, film type or
printing materials? Easy, if you have a Matrix. For any change or
combination of changes, do the following:
Select a subject typical of one's work that satisfies the following:
Zones I & VIII are represented in large areas.
Note: It may help to place some large panels of uniform value into the
scene.
Carefully visualize how the print should look, and take notes.
Note: This is a very important step.
Expose and develop and print for "normal" as defined by the Matrix.
Compare this print with the Matrix.
Find the Zone I that matches along the exposure axis.
Find the Zone VIII that matches along the development axis.
Calculate the adjustments need to bring this test to "normal".
Example: If Zone I matches the Matrix at "normal" plus half a stop
and Zone VIII matches the Matrix at "normal" minus 10%,
then, to compensate for the change of equipment, film, printing, or
whatever, decrease the exposure by half a stop
and increase the development by 10%.
To verify, re-photograph the subject with the corrected exposure and
development times. Zone I and VIII will now match the "normal" of the
Matrix.
This procedure is really handy whenever a new paper is used. All the
previous work of making the matrix is preserved and can be utilized.
Hope this will be helpful.
Jeff