Cole Images: film times & development
Some notes on film calibration and processes
Disclaimers
I am always hesitant to post times that I have arrived at through careful and often tedious calibration, experiment, and luck. Calibrations of lens and camera are equally eccentric and seldom do two photographers come up with the same results due to variances in cameras, materials, and techniques. The calibration process is at best personal and dependent on the total equipment chain: light source, light meter measurement technique, chemistry, temperature control, techniques too various to be discussed; and most importantly the film exposure. Please take these notes with this in mind. I have had many requests for times and I always point the inquirers to http://www.digitaltruth.com/ and their Massive Development Chart for beginning times.
Currently I use as a standard film in ULF large format a widely available and inexpensive EFKE PL 100 film. Alas my stash of old yeller Kodak's Tri X and Super XX and such are dwindling. Agfa 25 and Technical Pan 2415 recording film are being discontinued. There are several good films available today in the 2007 era and I will not argue the merits of this field
Kindly take these notes for what they are worth to you. You will be angry with yourself if you can not remember a critical step or the results of this time consuming process.
Equipment and materials used in this discussion:
A fine modified Saltzman 10X10 inch enlarger with an Aristo variable cold light head ~ 40X40 inch vacuum easel and a 96 X 72 inch auto advance seldom used aerial roll paper vacuum easel.
Durst 139 S one color and one with an Aristo cold light
Durst 1200 one color and one with a contrasty point light source.
Other miniature Leitz and Rollei enlargers for those using 35mm and medium format w/Schneider APO lenses
GrayLab 900 progressive timers with infrared remotes and foot switches.
Rodenstock and Schneider 300 and 360 APO lenses (plus some exotics)
A 360 degree rotating film carrier(Saltzman) and a fine custom Saltzman automated 10 inch roll carrier for our aerial films and a synced auto advance roll paper easel.
I usually recommend that anyone who wants to produce good black and white prints start in the field first with new film and familar equipment. Simply take a few test shots . I stress the KIS ( keep it simple) approach. Most panchromatic films I have teasted are best shot at half or so of their advertised asa. An example would be Kodak's Tri X 320asa is usually calibrated to 160asa in D76 or HC110. This will vary widely with developers, but this is a good start with D76 and similar developers.
Start with one good normal focal length lens, one view camera, one process, and learn to produce prints with these. Later lessons learned from this will help you deal with other combinations. We are looking for a print that shows adequate shadow detail initially. Kindly try not to add new variables as this will cloud if not confound your efforts.
Keep accurate and detailed notes.
Generally speaking a color head and a cold light head produce very similar results, but I feel that point light and condenser light sources are for highly specialized work. Cold light enlargers are easier to print on with fewer dust spot problems. but require a denser negative. I keep the Durst point light source head for technical work,copy printing, and for the occasional old negative developed for that source. My densitometer tells me that negatives for condenser light sources need to be cut back about 0.76 to 0.85 of the density of a good difussion or cold light negative. In our workshops we cover more detailed proceedures; and elaborate on on the scientific and boring mathematical aspects (if guests are interested), but here we are simply looking for a good film working speed for our own use.
You may want to try my calibrations. They may just work for you! If so you can skip this tedious process, and go out and make some images. Enjoy!
Overview
First we will determine a working film speed.
Secondly we will calibrate our system so as to produce a negative that will prints our highlights.
This is a simplified home or field approach without the need for laboratory tools such as densitometers.
Step I.
Determine a practical film speed. We will use four sheets of film.
Bracket your film in 25 asa increments. Example Kodak Tri-X 320 at 200, 175, 150, and 125 asas. One of these should be close to your calibatred negative. You can further refine this by cutting down the increments or do what most do -- guestimate. If you have access to a densitometer, contact me and I will send you another more precise method of calibration.
Light: mid morning or mid afternoon bright sun. Be consistant.
Use an accurate light meter, and a subject with plenty of shadow detail.
I use a nearby brilliant white house with a deep shadowed and a cluttered porch ( loads of detail with a large double black door).
If you have a spot meter take an average reading on the shadow and the light areas. If you have an incident meter use a simple reading of the porch shadow area facing the sun light source. On a Zone IV Pentax digital meter this will be usually from 9:++ to 10:++.
14.++ is a direct light reading of a gray card in bright sunlight.
For Ilford FP4 125 I used 64 calibrated asa in either ID11 or D76 1:1 dilution. This is a fine film to start with. It is readily available as are chemistries for it.
For Tri X 320 pro films or the 400asa I calibrated the film to 160 asa with D76. This is a fine combination if you can find the film.
One caution: Ektapan and several other popular films were created for studio lighting, and respond best to the makers recommendations. These will work in daylight, but why not use emulsions designed for that use?
EFKE 100 asa shot at a known calibration of 80 asa I use a shadow exposure is about a 1/4 to 1/2 second at f32 .
A a normal sunlight reading is usually 1/8th @ f32 . Please do your own metering as this is part of your finding an asa that works for you. One has to throw out traditional densitometer readings for 0.10 above film plus base plus fog with the combo of PMK pyro and EFKE 100. EFKE can be pushed well but not pulled. All manufacturer's data and their representatives caution about overexposing this film. Throw those Ansel Adams books away on this combination. You do not need to overexpose this film normally as it represents shadow detail well. The lower sped EFKE m 50 PL and the 25 have a curious almost orthochromatic curve(see their spec sheets and graphs). Both of these represent shadows well and see folage with detail. This film prints some spectrums of red as a zone six or above, and greens are darker. If you use filtration use the EFKE filter chart. Panchromatic filters can produce bizarre results with orthochromatic. Run your own tests.
Highlights such as mountain snow or hight contrast summer towering cumulus are delicately rendered as no other combination that I have tried.
Step II.
Develop the film at the recommended Normal time, Create a temperature control system as best you can. Evaluate the resulting print for shadow detail. I use a six foot stainless container for my 2.6 gallon stainless tanks and an accurate Calumet temperature recirculating bath to maintain a constant 20 degrees C. I use dip and dunk for most of my work. I do not use other methods and dislike tray gang ( several negatives stacked) development of negatives. I had to do this in the Marine Corps in Korea and the Phillipines in 1950, but ususlly suffered damaged negatives. Tube processing is popular and work well. Jobo systems are fine, but expensive. I have little experience with this other than Cibachrome drum processing for large prints -- 20X24 normally.
Below are some of the times I have used. Be cautious as these work for me in my darkroom, but you need to calibrate your own.
Step III.
Using our shadow determined asa (film speed) shoot an area with brilliant highlights and some shadow. Meter as before but note how far the brightest element you desire to have detailed highlights is above Zone V or a normal gray card reading in sunlight. Example: Zone V is 14:++ on a spot meter then count three zones above that. A bright white painted wall will meter on my meter 16.++ to 17+. You may want some detail in zones above that as in snow in bright sunlight. With the meter set at you corrected/calibrated asa take an average reading with a program incident meter such as the Minolta IV or on a spot meter you can simply move the highlight required number opposite the max highlight symbol or mark. The number of you move the meters scale down may be two to four stops. This number determines the under development or compensation effect we are seeking to produce a print with detailed shadow and printable highlight areas.
This may be from reducing process times, or by dilution of the developer. Agitation patterns can be used up to a point.
http://www.largeformatphotography.info/articles/ZoneDial.pdf This fine site has a good illustration.
I made a zone tape using the below layout for my Pentax Digital Spotmeter. I highly recommend this meter.
The numerals represent zones one through nine.
Zone I is approaching pure black and Zone X is paper white.
Zones 0 1 2 3 4 5 6 7 8 9 10
We are here classically over exposing for the shadow andunder developing the film for the highlight. This only works with conventional films and developers. More on this when we get to compensating developers and the some what Orthochromatic films like EFKE M 25 PL and M 50 PL films and true ortho emulsions.
See DigitalTruths site for technical data on these films.
My times for the venerable Kodak Tri-X Pro 320 asa at a calibrated film speed of 150 asa. HC110 dilution B see foot note number 3.
MINUTES
N + 3 20:20 ~ For better results try a stronger dilution or a more active developer.
N + 2 15:08
N + 1 11:40
Normal 9:00
N - 1 7:30
N - 2 6:12
N - 3 5:00 ~ Better results with compensating developers or with pre bleaching.
N - 4 & lower NOT RECOMMENDED Try a dilute compensating developer or pre bleaching for N - 5 to N - 10.
Large tank development in hangers
Agitation two eight seconds dips per thirty seconds. I set my Graylab 900 programable timers to beep every thirty seconds and time the dip and dunks to end on the bell. Of late I have begun to use two timers with the second as a backup. I experienced a timer malfunction and had to count for fifteen minutes. Bummer!
Never again. You may have a agitation system that works for you. If it works use it. Consistancy seems to be the most important factor. My agitation starts constant for thirty seconds then two cycles every thirty seconds.
Thus: 0 to 30 seconds constant
52 to 00 seconds two cycles
22 yo 30 seconds two cycles
and so on >
More agitation produces more contrast.
Less agitation less contrast.
Inconsistant agitation guarantees unpredictable results.
Step V:
Print on a good normal contrast paper and tone to your taste. If you use a color head or cold light source and VC paper start with your manufacturers recommended filtration.
Expose and develop the print in fresh developer and chemicals. Carefully examine the dry print. Simply adjust you asa(exposure) and developing times to produce the results you desire. Blocked highlights require less development or dilution. poor shadow suggests more exposure.
I look for good shadow detail, accurate mid tones, and brilliant but subtly defined highlights. I have worked in bright mountain snow and find that subject presents one of the most difficult highlights to control. PMK pyro and most classic films handle this with ease. More on mountain shooting and why it helps to have a good color meter.
Quote Try it -- you'll like it. from Mikey the cereal kid
Compaction notes: Creating negatives of high contrast subjects that will print well on normal papers,
Normal overexpose for shadows and under develop for the highlights produce some bizarre results in the accuracy of the mid scales in the final image. Sometimes this produces artistic and desirable results. but I much prefer the normal scale in my prints.
An excellent series of articles by David Kachel appeared in Darkroom Techniques in the May/June issue # 3 and in several following issues.
Contrast control using multiple exposures. Below is a double exposure scenario,
Example: Harsh sunlight on bright white marble surrounded with dark woods shadows.
Cloudy day.
One sheet double exposed. Camera firmly anchored. I use 25 pound bags of shot.
1. When the sun goes behind a cloud meter and expose for shadows. Say 1 second at 32.
2. When the sun comes out do a second expose for the bright highlights of say 1/30 at f32.
This method employs normal development, and yields negatives that print on Grade 2 paper.
Try a twilight shot of a building with normal exposure for the building, and a secong exposure after dark exposing for the interior lights. With color a color meter is required to balance daylight to the artificial interior light. You need to filter the second exposure according to the color of the mixed light.
Pre development image bleaching with dilute Potassium Ferricyanide
Pre image bleach with Potassium Ferricyanide for compactions of minus six or seven +.* This process may effect your asa calibration, but I have not had to change it.
Prebleached negatives are exposed for normal light and developed for normal times. This is true of every level of compaction using this process. The resulting negatives have an accurate mid tone scale as opposed to the overexposed under developed negatives which ofter produce wildly distorted mid tones.
I appreciate the delicate highlight separations and the true rendering of shadow to mid tone.
Pre bleaching was introduced to me by the Master David Kachel. I had tried several other reducers and bleaches, but failed miserably to achieve my goal of a printable negative. His articles in Darkroom Techniques in the 1989 era are well worth researching and will be classics. I greatly admire this fine man, his writing skills, and his brilliant work.
Another technique that David Kachel has pioneered is latent image bleaching. His investigations of historic image manipulation techniques led him to (re)discover that images can be bleached prior to development and that such bleaching has the opposite effect to bleaching developed images. The greatest reduction will be achieved in the area of film or paper that has received the greatest amount of exposure. With film, it is the highlights that will be reduced by pre-bleaching, whereas with paper the shadows will be reduced. Latent image bleaching provides a new level of control for creative photographers.
Use of pre bleach: example
My calibrated times are for Tri X 320 @ 150 asa.
Meter for normal light or if shadows predominate-- for an average shadow reading.
Pre bleach the negative for the below times:
To mix the Potassium Ferricyanide 1:1,000 H20.
To make a 10% solution of potassium ferricyanide, add 100 grams of
potassium ferricyanide to 800 milliliters of water at room temperature,
stir until dissolved, then add water to make 1 liter. For negative
bleaching, distilled water may be preferable. I installed an RO unit in my darkroom. I do not use this method, but it can be convienent.
Some
negatives require the addition of potassium bromide to the solution to
reduce fog. Kachel recommends 1 part potassium bromide to 3 parts
potassium ferricyanide. This would require the addition of 33.3 grams
of potassium bromide to the above stock solution.
I use 4 grams Potassium Ferricyanide and 1.33 grams of potassium bromide to three quarts and add water to make one gallon since my small tanks are of that volume. This is not a 1/1,000 dilution.
This solution will keep for months in my experience, but I usually only use it for the batch at hand. It is not an expensive brew.
Try Pre bleach the negative for the below start times.
Pre soak for at least two minutes. I do not like to use soap on my negatives, and use RO or distilled water.
Some starting times that should be in the ball park
20 degrees Celcius Times less than 5 minutes may produce uneven results. I usually use reduced development for N - 1.
N - 1 3:00 minutes I use a gentle constant agitation cycles for this short time.
N - 2 4:15 I use a gentle constant agitation cycles for this short time. N - 3 5:36 Normal agitation cycles through N - 8.
N - 4 7:30 N - 5 10:00 My most used compaction
I have begun using a more concetrated bleach for N - 6 and below. Try using 8.0 grams Potassium Ferricyanide and 2.66 grams of potassium bromide to three quarts of water and add water to make one gallon Strarting times;
N - 5 6:00 minutes My most used compaction -- works well.
N - 6 8:30
N - 7 12:00
N - 8 16:50
Rinse for four minutes or use constant agitation in a large tank to rid the negative of bleach. I do not use stop, but using it on most film processes does little if any harm to the negative. Since I use PMK pyro and redevelopment I can not use stop baths.
Develop normally!
Develop for the Normal time ( 9:00 minutes for Tri-X 320) and then treat the negative as any other. You are on your own below this. We created a N - 10 lighting setup and it worked well. That exercise was mere curiosity. Almost all of my work with the Kachel process
of pre bleaching has been in the area of N -3 to N -5.
This seems to work best with thick negatives like Berrger 200, Tri-X, Super XXX, and EFKE films. David Kachel used this with Tech Pan 2415 recording film (alas stolen from us by ole yeller Kodak) with normal exposure. AT 25 asa That produced dense highlights which he bleached down to a printable density. I do not beleive that we will see a similar film again.
It was magic with the now discontinued Agfa 25 pan and the old thick emulsion films.
I have seen some amazing compactions achieved with this method.
Have fun and let me know if these work for you.
Some links relating to the above:
http://www.zonesystem.com/
http://www.kodak.com/global/en/professional/support/techPubs/o3/O3wp4.jhtml
http://unblinkingeye.com/Articles/Mortensen/Mtnsn2/mtnsn2.html
http://photography.about.com/library/weekly/aa082800c.htm?terms=darkroom+print On mixing chemistry
http://chemistry.about.com/library/weekly/aa081003a.htm
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