Maker: Director Products
Designer: Donald W. Norwood
US Patent #: 2,972,930
Price (new): $18
Cell type: Selenium
Measure type: 3D incident
But the M-3 was a meter unto itself.
This was Norwood's attempt at a direct-reading meter, one where you pre-set the exposure index and shutter speed, and the meter needle points to the ƒ/stop to use. It would compete with GE's Mascot, Weston's Cadet and DR, and others.
Direct readers all need some kind of gimmick to pull off this trick, and Norwood used their system of calibrated, perforated metal slides. You'd pick out a little metal slide with holes in it, and the slide had a film speed and shutter speed marked on it. Insert that into the top of the meter (just below the photosphere dome) and the meter was set. These are great for movie cameras, but not very good for cameras.
The meter originally came with two slides, both set for ASA 10 (Kodachrome); one was for movie cameras at 16fps (shutter speed would be around 1/25) and the other for still cameras at 1/50th. You could buy other slides from a photo dealer, or do the conversions in your head if you wanted to use different shutter speeds. I've never seen other slides for sale (not for the M-3). It would have been nice if the slides were compatible with the M-2 or the Spectras, but no such luck; it would have ruined the shape of the meter. If you really wanted to, you could make new slides out of a slim piece of sheet metal or wood, but I would think figuring out the number and size of the drill holes would be more trouble than it's worth.
About the size of the butt of a large cigar, it comes with a clip for your pocket or coat lapel (and one ad showed it on a shirt cuff for hands free operation). It's also very light. But I wonder if it would have been better with a neck string, like most other meters. I imagine a lot of these have been dropped. I got an email from someone who told me he never saw one which worked; both of mine actually do, though I never checked their accuracy. A lot of these old meters sit for years and the movements get sticky. Both of mine came back to life when the slide was removed, they were put under bright light and gently jiggled. My old General Electric PR meters have sluggish movements as well.
I also think it was a mistake that it was never named. Director Products did a lot of strange things, and they decided to make the Norwood Director a "name" and the latest version a Model M-2, so this became the M-3. I don't think there was ever an M4.
Nifty little meter. When Director Products / Brockway went out under, the Director and Super Director both had later lives with Japanese makers, but the M-3 disappeared entirely.
If you want to see the inside of this thing, it's on my disassembly page.