Sensitometers...might want to get one soon...

I think many on this forum have experienced waxing and waning of interest in darkroom equipment. For example, my experience is the golden age of free and inexpensive darkroom equipment is already past. Just try to find a nice large format enlarger these days. It is getting harder and harder.

However, sensitometers are still available, but the availability is nearing the tail of availability. The availability is from the somewhat recent dump of analog equipment that occurred when Breast Mammography (the last radiographic holdout of FILM) finally went digital to join most of the other radiographic studies.

Why want one? In the past, analysis of film was time consuming, math intensive, and required expertise and information not commonly available to the average darkroom worker. However, today, forums like this and the internet in general, make all the research on film testing available from the comfort of one's home. Also, the availability of computers makes analysis of film data retrieved from the sensitometer almost trivial compared to the hours and years spent in the past.

For example I recently got some Shanghai 8x10 film. It only took a few moments to expose a strip in the sensitometert (hardest part was cutting an even strip to fit a 35mm film reel for processing), process the strip, dry with a blow dryer and read the values with a densitometer. The most challenging part was entering the data to my computer software with the goofy new keyboard that came with the new iMac I'm typing on now (no extra number keypad ) Almost instantly the software graphed the data and gave me a relative speed (compared to a fresh name-brand film) and gamma and almost as important, showed me the shape of the H&D curve. Way easier than trying to calibrate a monitor and color printer for the 'other system' of image reproduction.

By natural progression, other imaging modalities then adopted the digital technology. The transition from conventional mammography to its digital counterpart, however, was delayed due to the difficulty of producing a full-field digital detector

Biomed Imaging Interv J. 2008 Oct-Dec; 4(4): e31.
Published online 2008 Oct 1. doi: 10.2349/biij.4.4.e31
PMCID: PMC3097746
PMID: 21611016
Digital versus screen film mammography: a clinical comparison
Y Faridah, MBBS, MRad

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Worth thinking about, makes a lot sense for those of you that use 8X10, even 4X5, when I did a speed test with Forma 400 4X5 used 35mm for a ring around. but a sensitomerers or densitomer is more percise.

ic-racer said:

... It only took a few moments to expose a strip in the sensitometert (hardest part was cutting an even strip to fit a 35mm film reel for processing), process the strip, dry with a blow dryer and read the values with a densitometer. The most challenging part was entering the data to my computer software with the goofy new keyboard that came with the new iMac I'm typing on now (no extra number keypad ) Almost instantly the software graphed the data and gave me a relative speed (compared to a fresh name-brand film) and gamma and almost as important, showed me the shape of the H&D curve. Way easier than trying to calibrate a monitor and color printer for the 'other system' of image reproduction.

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+100

I looked on eBay and only see sensitometers designed for blue and/or green sensitive x-ray film. That doesn't seem useful for pan-chromatic film? Can you point me to any example device that has a daylight balanced light source?

mjork said:

I looked on eBay and only see sensitometers designed for blue and/or green sensitive x-ray film. That doesn't seem useful for pan-chromatic film? Can you point me to any example device that has a daylight balanced light source?

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Color of light source does not change the film's ability to respond to changes in development. Most panchromatic films for which spectral sensitivity is reported have similar same sensitivity to green, blue or red. You can see in the composite below.

Having reported that, I don't see why the LEDS in a Green or Blue sensitometer could not be swapped for white if it would make one sleep better. It may be an interesting project (though maybe not needed if only comparing films of similar spectral sensitivity)