When I first put this Canonet 28 rangefinder camera on my test bench I was disappointed. It was out of spec, overexposing at all light levels. But the error was curiously consistent. I decided to try with a different voltage battery and lo and behold: it worked perfectly with a (cheap and easy-to-find) 357 silver oxide cell.
The exposure accuracy was excellent for its entire metering range of ISO 25 to ISO 400. Clearly, at some point this camera was modified to work with 357 batteries. And it was done very well. More on this mod later if you're interested in film camera electronics.
The Canonet 28 is designated the 'New Canonet 28' in The Canon Museum to avoid confusion with the less successful or capable zone-focus camera of the same name from 1968. This 'New' Canonet 28 was a hit for Canon, remaining in production from 1971 to 1976. Often overlooked in favour of its more feature-rich (and expensive) sibling, the G-III QL17, we find the 'New' Canonet 28 is quite close in terms of image quality and is a bit easier to use. We'll drop the 'New' from here on.
It's a pleasant experience using an unmodified-but-working Canonet 28. The camera is beginner-friendly and has a sharp 40mm f/2.8 coated lens. Though the original PX625 batteries are no longer available, 675 zinc air cells are inexpensive and do the job. But this mod takes the camera up a notch in terms of convenience: silver oxide batteries have a much longer life than zinc-air (two years or more vs. one to three months).
We've generally found the Canonet 28 to be very well-designed and dependable with one major exception: Canon used brittle plastic rivets to hold the negative battery contact in place. These rivets break and the battery contacts lose tension causing intermittent operation. Almost every Canonet 28 (and Canonet G-III QL17) we find has this issue. Attaching the contact with quality, slow-setting epoxy (as we did with this camera) is a reliable and permanent fix.
The camera above is the subject of this post, available for sale here.
A better point-and-shoot?
We've always loved small rangefinder cameras with auto-exposure (AE) like the Canonet 28, the Konica C35, and the Minolta Hi-Matic F. They match point-and-shoots in terms of ease-of-use but, at least in our experience, yield a higher "keeper" photo percentage since the photographer is in charge of the focus. No autofocus system yet devised is truly perfect. The circa-2021 Nikon Z5 mirrorless (and charmless) camera we use for product photos does a terrible job at autofocusing on anything darkly coloured.
With an AE rangefinder like the Canonet 28, you're in charge of focus and composition but the camera handles the shutter speed and aperture.
Tricky conditions can still fool the light meter but moderate underexposure (and especially) overexposure is usually pretty recoverable in the darkroom or in software. But there's not much you can do with an out-of-focus photo.
The camera doesn't have a built-in flash (a feature to be introduced with 1977's A35 Datelux 'Nighter') but it works with any ordinary flash. Like the Konica and Minolta mentioned above, it's designed to make flash photography very easy. Check pages 14-17 in the manual for more on flash photography.
Film testing and processing
We loaded the Canonet 28 with a roll of Kodak Tri-X 400 on a spring day for testing. We soon realized this was maybe a poor choice as the light was very bright and harsh that day in Montreal (ISO 100 or 200 film is better in full sun). As a plan B, we could have brought a neutral density filter (this camera accepts 48mm threaded filters and the light meter automatically adjusts). But we didn't think of this in time so we just shot the roll.
We were at the very edge of overexposure most of the day (the shutter locks if the Canonet's light meter detects overexposure). Ideally, you don't want to be taking photos at the edge of the exposure range due to a phenomenon called diffraction where you lose a bit of sharpness. Nevertheless, we were pretty happy with the photos we got.
We developed the film using Flic Film Classic MQ developer (1+1 dilution) in a UniRoller rotary processor (note: it says "D76" on the clapperboard image below; Classic MQ uses the D-76 recipe). The other chemistry used was Kodak Indicator Stop Bath and Flic Film Quick Fixer. We scanned the negatives with a Nikon Coolscan V ED.
The developed negatives on a light table
Canonet 28 test photos
Taken on a (too) sunny Montreal afternoon in the spring.
The Canonet 28's Light meter (and how this one was modified)
Warning: This gets a bit technical and is probably only of interest to people curious about vintage film camera design.
As mentioned earlier, the Canonet 28 was designed to use a PX625 mercury battery. The PX625 delivered a very stable 1.35 volt output for the duration of its long life. It was banned in most countries by the 1990s due to mercury content.
Typically you'll see type 675 zinc-air hearing-aid batteries used as a substitute; the voltage is correct under load and they're cheap. But the downside of zinc-air batteries is their short lifespan (usually a few months max). Also, zinc-air batteries prefer moderate weather: they die quickly in very hot weather and lose their voltage stability in very cold conditions. Silver-oxide 357 (also called SR44) cells can last two years or more and they perform better and more accurately in very cold weather.
The modification is a bit tricky. It must have been done by a competent technician with access to the service manual.
The camera has a relatively simple schematic (shown below), but it only allows you to electronically adjust the light meter's response to very bright light levels (the variable resistor X64 in the schematic).
It might be possible to modify the circuit with what's called a 'shunt resistor' connected to one end of the galvanometer and also to ground. But this would require a lot of experimentation and might not work since the characteristics of the CdS cell (the light-sensitive element) and the galvanometer (the movement that drives the needle) aren't given.
It's also possible to solder a Schottky or germanium diode in series with the battery to drop the voltage. We don't love this approach as it introduces an exposure error at the extremes of the light meter's range (and this error gets worse in very cold or hot temperatures).
I took the camera apart to clean its viewfinder and adjust its rangefinder and I could see no evidence of electronic modifications. Instead, the technician must have done the more involved total response calibration shown below. This mechanical adjustment requires extensive disassembly and access to an (expensive) luminance meter and a variable light source (the cd/m² values are non-standard).
Figure 2. The mechanical exposure accuracy adjustment from the Canonet 28 service manual. "EE" meaning 'electronic eye' is an old term that was formerly used similarly to how we now use 'automatic exposure' or 'AE'.