When I took the helm at Photo Techniques magazine in 1994, the outgoing Editor, David Alan Jay, told me that the three things readers most needed to "fully participate in the life of the magazine" were a large format camera, a spot meter, and a densitometer. I subsequently became good friends with the late Phil Davis, the magazine's de facto Technical Editor (he didn't want the actual title because he felt it would make him responsible for what he considered other peoples' idiocy). Phil, a Professor Emeritus of Photography at the University of Michigan who had made his fortune as an advertising photographer of Detroit cars, was a devoted user of the densitometer; he loved nothing better than to test new films. He computerized his efforts with a wondrous program called the Plotter/Matcher, which unfortunately now only runs (as far as I know) on antiquated Mac operating systems [UPDATE: This is wrong—Don Bryant tells me there is a version for PCs sold by the View Camera Store, keeper of the BTZS flame —MJ]. I keep an old Mac around just for it. The P/M's usefulness was severely limited for most people because Phil refused to share his data (my privileged position earned me access)—he wanted people to do their own plotting. Being a degenerate populist, one of the things I'd do if I won the lottery would be to create an online version of the Plotter/Matcher with the data for every existing black-and-white material available to everyone at the click of a mouse. Information wants to be free, as they say.
Before I go on too long (and I do go on), I remain delighted by David Jay's incongruous apotheosizing of the transmission densitometer, which is probably the most arcane accessory in a still vibrant but admittedly small niche of photography. Even people who have multiple LF cameras and lust after things like lantern Petzvals don't have, and in some cases have never even used—or even seen—a densitometer. The devices therefore exist on a cloud-wrapped sphere of esoteric extremity, a sort of photo-mysterium, bathed in obscurity and familiar only to a closed priesthood of insider initiates. In reality, they are relatively simple, pleasing, and robust optical-mechanical devices, and almost laughably easy to use—you almost don't need to read the manual. Plotting Hurter & Driffield (a.k.a. characteristic) curves or film testing for the Zone System become easy-peezy.
Models that survive
With the recent cave-in of film, the product market for professional (real professional, I mean, not consumer-marketing professional) equipment related to film has imploded. Only a few transmission densitometers suitable for black-and-white film photography remain. Of the two I've selected here, one is made to special order, and the other is aimed at the X-ray industry—itself making the changeover to digital, albeit at a more deliberate pace. There are of course others as well—this isn't a comprehensive list. These are just the ones that appealed to me.
With the caveat that I have never used (nor seen!) the following specific models, an evening's research last night and some time on the telephone this morning have caused these to bubble to the surface as most likely being good ones for darkroom hobbyists. The first is the Fluke Biomedical 07-424 Digital Densitometer, previously known as the Nuclear Associates 07-424 or the Victoreen 07-424. These are now made to order, with a six-week lead time, at a cost of a little over two grand. Used ones often go for very little on eBay, but beware—they require three little insertable apertures, little aluminum disks that resemble washers. Most resellers of densitometers online aren't users of the devices, and commonly don't know how to test whether they are working properly or whether or not all the requisite parts are included. I believe Fluke may be able to sell you the apertures as replacement parts, however.
The other photo densitometer that looks promising to me for hobbyist use is the Eseco Speedmaster SM-10T. Made in Oklahoma by a going concern noted for good customer service, the SM-10T is a simple-to-use and robust little device that sells new for $1085, which is very reasonable as new densitometers go. It's only 11 inches long by 4.5 inches wide and high, and actually runs on two 9-volt batteries, although you can plug it in using a power supply if you'd rather.
I'm going to ask the folks at Eseco-Speedmaster and Fluke if they'd like to have these models reviewed. They might not care; we photographers can't be much of a market for them. If they do (and maybe even if they don't), I'll write more about how you use densitometers and what photographers use them for.
UPDATE #2: Mani Sitaraman informs me that the excellent Heiland TRD2 is still available from the very interesting John Bicht at Versalab. My web-rummaging last night failed to uncover that. The Heiland unit was reviewed by none other than Phil Davis at Photo Techniques during my tenure there. (By the way, I will say that the version that appeared in the magazine was better edited!)
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Original contents copyright 2011 by Michael C. Johnston and/or the bylined author. All Rights Reserved.
Featured Comment by Karl: "I once set up a small lab to service a really large customer, and bought processors from Eseco. They're really a great little company, with top-notch people."
Featured Comment by William Schneider: "Some commenters asked about calibration targets. They are still available from Stouffer Industries. Available are both transmission and reflection targets, and the items come calibrated and uncalibrated. I bought some reflection and transmission step wedges to calibrate both an Eseco Speedmaster, and to do some experiments to see if I could get a flatbed scanner to work as a densitometer. (Yes, I could.)"
Featured Comment by Ed Cornachio: "Ah, nostalgia! What next? Extinction light meters? I remember graduating from an "extinction" to my first Weston light meter (placed detailed shadows on Zone III and developed detailed highlights to Zone VIII.) Etching 4x5 negatives with bits of glass shards to reduce density in small, local areas. Making my personal 'palette' of Spot-tone (warm, neutral, and blue) on a sheet of clear glass sandwiched to white cardboard, and carefully swiping my #1 and #3 sable-haired spotting brush on the tip of my tongue for just the right amount of moisture. (Very distinct taste, Spot-tone.) Varigam paper: primary exposure with a five, but kiss it with a ten for a couple of seconds for extra zip. Ah, nostalgia indeed!
"Bring back the soothing, hypnotic light of red and amber, and the sea-like odor of sodium thiosulphate."
Mike replies: Ed, you laugh, but I actually have an extinction meter—a gift from Phil.
Featured Comment by g carvajal: "You lost me at 'When I took the helm....'"
Featured Comment by Hugh Crawford: "Freshman art school photo major: 'So what's this densitometer thing that the sign says I can't use until the second year?' Graduate art school photo TA: 'It's the thing we use to see if you are smart enough to stay in the Photo Department or if you are so dense that you will have to transfer to the [Drama, Music, Painting, Animation, Dance, Film, Critical Studies, pick the one most likely to offend] Department.'"