X-Ray Film Exposure Test (Cranberries)
This article was updated on to include links to x-ray film online retailers.
This is a series of shots I made to work out the exposure characteristics of Kodak Ektascan B/RA film. Ektascan is an orthochromatic x-ray film sold in 8″×10″ sheets and larger. I cut it down to 4″×5″ for use in my Wista 45DX wooden field camera kitted with a Schneider Symmar-S 5,6/150 lens. I used a yellow-green (X0) filter but made no allowance for a filter factor, bellows draw, or reciprocity.
The 1st image is an unaltered scan1 made on a very old consumer-level flatbed scanner. The 2nd image was made by adjusting the curves in Adobe Lightroom® 5 for higher contrast. Because the film has a blue polyester base, whites appear as light grey to the scanner, so 1 of the adjustments involved resetting the white point in the curves.
Light Meter Readings
The scene was illuminated by natural light from a window under cloudy conditions in the early afternoon. My reflected reading was .7 seconds for ƒ/5.6 at ISO 80. Incident reading was 6 seconds for ƒ/5.6 at ISO 80. This works out to:
- 1 second at ISO 25
- ½ second at ISO 50
- 6 seconds at ISO 80
- 3 seconds at ISO 160
Starting from the left to right and top to bottom, the exposures were made at ½, 1, 3, and 6 seconds at ƒ/5.6.
I developed the film under a 7-watt red safe-light 1 sheet at a time to avoid scratches (x-ray film emulsion is very soft, so the “shuffle” method is inadvisable).2 I employed tray development to allow visual inspection while processing. Negatives #2, #3, and #4 were developed in 66½° F. (19.17° C.) Pyrocat HD diluted 1:1:200. Negative #2’s developer was just below 65° F. (18.33° C.); it was processed the next day when the ambient temperature was cooler.
I soaked each negative for 5 minutes in plain water, then employed semi-stand development. Except for negative #1, I developed for 15 minutes, with an initial “brush” agitation using a 3″ “Hake” brush. I brushed gently north to south and back for a total of 5 times in each direction, waited 5 – 10 seconds, and repeated for a total of 25 agitations per direction during the 1st 2 minutes in the developer. At the 7½ minute mark, I brushed 5 more times (5 north and 5 south). After 15 minutes total development, I transferred the negative to a plain water stop bath. I fixed for 8 minutes with Kodak Kodafix, turning on the room light halfway through, then washed in cold running water for 5 minutes. I used a drop of Form-a-Flo washing agent during the final rinse and then hung the negative to dry.
I disposed of the developer after each negative and started with fresh “soup” for each new negative.
Because negative #1 was badly underexposed, I repeated the 5 north-5 south agitation at 15 minutes and again at 22½ minutes. I left the negative in the Pyrocat for 37½ minutes more, with no further agitation (total time 60 minutes). This eventually brought out the shadows and revealed the highlights, but at the expense of a very low contrast image.
Negative #3 is, mysteriously, darker than negative #2, even though it was exposed for a shorter interval and processed exactly like #3 and #4. It also exhibits uneven development and mottling.
Scratches are visible on all of the negatives, but compared to my 1st attempt using the “shuffle” method, they are minor.
Darkroom Equipment and Chemicals
I used the following equipment and chemicals:
- 5 – 5″×7″ smooth-bottomed enamelware developer trays3, purchased from eBay
- 3″ hake brush
- Delta 1 brand 7-watt Junior safelight
- Metal clamp work light with reflector, for safelight
- GraLab Model 300 darkroom timer
- 1000ml graduated cylinder, for measuring developer
- 10cc syringe, for measuring developer
- 1000ml glass lab beaker, for mixing developer
- Chemical stirring paddle
- Exam gloves (pyro developers are toxic and can be absorved through the skin)
- Kodak Process Thermometer Type 3 (no longer manufactured, but available on eBay), for calibrating tray thermometer, see below
- Weston dual scale darkroom thermometer
- Photographers’ Formulary Pyrocat-HD in Glycol film developer
- Kodak Kodafix
- 16-ounce plastic funnel with built-in fine-mesh strainer, for returning working solutions to storage containers
- 8-ounce bottle, for storing photo fix working solution
- Photographers’ Formulary Form-a-Flo wetting agent
- Stainless steel film clips, for drying negatives (I attached them to these hangers and suspended them from the shower curtain rod — did I mention that my darkroom is the lavatory?)
I did not use a clearing agent, although I have some Kodak Hypo-Clear; it doesn’t seem worth the bother, especially for washing film — if I were making prints, that would be a different matter.
M-mount lenses do not provide aperture information to the camera body, either electronically or mechanically. Therefore, f-stop settings are approximate, and are probably wildly inaccurate. For what it’s worth, I usually shoot with my lenses wide open.