Film Test Procedure FT-1B

Record

• Date
• Test number
• Procedure
• Film (e.g., Kodak T-Max 400)
• Film roll number
• Film expiration date
• Developer
• Development time
• E_ref offset
• Exposure time

Check Setup

• Perform appropriate prep per FD-400TMY-XTOL-1.
• Paterson Proof Printer: positioned in portrait orientation with hinge at top
• Attach diffuser to iPhone front camera and start LM-3000 light meter app (screen brightness minimum)
• Enlarger:
  • Warm-up: leave enlarger on (focus mode on timer) for at least 2m
  • 35mm negative carrier installed (probably not necessary)
  • Height: 29.5cm
  • Lens: Rodenstock Rogonar-S f/2.8
  • Lens Filter: Kalt 80A (delta LogE=0.486)
  • Attenuator: -3 EV (actual delta LogE=0.85 or 2.826 stops)
  • Color Filter Bypass: on (white light)
  • Focus on foam of proof printer
  • Aperture:
    • Starting point is f/5.6
    • Position the light meter on top of the center of the glass of the proof printer.
    • Ensure configured per above steps
    • Lights off
    • Record illuminance on top of glass, record range (Note: illuminance at the film plane with glass over the film will be 0.1657 lx less)
    • Verify illuminance on top of glass is between 0.968 and 0.994 lx, if not check setup.
• Film roll: tape leader to enlarger base on right side of proof printer emulsion side up.
• Step tablet: position with emulsion side up somewhere where it can be found in the dark.
• Tank, reel, spool, lid: ready
• Scissors: ready
• Timer: set to 0.6s
• Safe light off
• Phone and any other light source outside of darkroom or covered, cover GraLab timer with cloth.
• CineStill TCS-1000 off
• Door/curtain secure
• Verify no light anywhere in the darkroom.

Expose

• Warm-up: ensure enlarger has been on >2m
• Open glass cover of proof printer
• Lights off
• Pull out film to cover proof printer width.
• Place step wedge emulsion side down centered over film.
• Lower glass
• Start timer
• Lift glass
• Put step wedge back in envelope.
• Pull out one extra frame to have an unexposed reference (base+fog).
• Cut (leave a little leader)
• Load exposed film into tank as normal.
• Lights on.
• Cinestill TCS-1000 on and set

Develop

Develop using normal procedure or adjusting times or temperatures depending on the goal the test. About one hour dry time is sufficient before moving on.

Measure

• Step wedge densities:
  • Only have to do this once, not every time.
  • Measure each step of the step wedge using a densitometer and record in a plain text file with one line per density starting with step 1 (31 lines total for 31 step wedge).
  • Save the file with a descriptive name, e.g., stouffer-31-step-wedge-densities-2025-10-03.txt.
• Film densities:
  • Measure each step on the film starting with step 1 using a densitometer and record one line for each measurement (31 lines total for 31 step wedge).
  • Measure the unexposed portion for base+fog density and record on the next line of the file.
  • Measure the fully exposed leader for D_max and record on the next line of the file.
  • Add another line with the best estimate of log of the max exposure, i.e., the log of the total lux seconds of light the step wedge was exposed to.
  • Save the file with a descriptive name, e.g., t-max-400-xtol-stock-2025-09-28-test3.txt.
  • For a 31 step wedge this file should have a total of 34 lines (31 for step measurements, 1 for base+fog, 1 for D_max, 1 for the log exposure).

Compute and Plot

Go to hdcurve and select the two files and click “Compute and Plot”. The H-D curve will be plotted and the contrast curve will be calculated.

Equipment and Supplies

• Omega C760 Enlarger with C760 Dichroic head
• Rodenstock Rogonar-S f/2.8 lens
• Unicolor Precision Darkroom Timer Model 760
• Omega -3 EV Attenuator (part of 429-330 kit)
• Omega C-700 Voltage Stabilizer
• Kalt 40.5mm 80A filter (to simulate 5000K daylight)
• Paterson Proof Printer (a very old version of this)
• LM-3000 Light Meter App with Diffuser and Cosine Corrector
• Stouffer T3110 31 step transmission step wedge
• Dektronics Printalyzer Densitometer
• Jobo 1520 UniTank with 1501 Reel
• Scissors
• Roll of T-Max 400 film
• Masking tape
• Blackout cloth to cover light leaks from enlarger
• Thermopen ONE
• Normal developing supplies (developer, fixer, stop bath, Photo-Flo, etc.)