Breathing New Life into a 1954 Metraphot 2 as the lightmeter for Konica iiiA

The Classic Duo

I recently set out to find a period-correct, shoe-mounted light meter for my beloved Konica IIIA.

For those unfamiliar, the Konica IIIA (1958) is arguably one of the finest fixed-lens rangefinders ever crafted in Japan. Famous for its magnificent, ultra-bright "life-size" (1:1 scale) viewfinder with auto-parallax correction, shooting with it feels almost like floating through reality. Its 50mm f/1.8 Hexanon lens is razor-sharp, but since it's a fully mechanical body with zero built-in electronics, finding a compact, reliable external light meter is essential for quick street shooting.

I managed to source a vintage Metraphot 2 light meter (made in Germany around 1954) from a gentleman in Australia. Visually, its tiny, shoe-mounted form factor looks like it was custom-made for the Konica IIIA. However, upon arrival and testing, the needle barely budged—moving only about one-third of the way even when aimed directly at the intense midday sun. After over 70 years of light exposure, the original selenium cell had severely degraded, rendering it unusable.

The Hack: Calculator Solar Cell Swap

Instead of leaving the Metraphot 2 as a purely cosmetic ornament on top of my Konica, I decided to attempt a modern DIY cell replacement.

• Finding the Donor: I salvaged a tiny solar cell from an inexpensive mini calculator. Amazingly, the physical dimensions were nearly a drop-in fit for the Metraphot 2’s front light chamber. I only had to lightly polish/file down the glass edges by a fraction of a millimeter to get a snug, seamless fit.

• Voltage & Sensitivity Shift:

  • The degraded selenium cell was outputting a weak 0.1V under bright conditions.

  • The modern solar cell produces up to 1.5V under identical light.

• Rewiring & Calibration: The mod itself was straightforward—just a couple of quick soldering points to connect the new solar cell leads to the meter's galvanometer circuit. Because the output voltage curve of a solar cell differs from selenium, I had to reset and recalibrate the mechanical zero-adjust screw and test it against a trusted digital light meter across different EV levels.

The Result

It works shockingly well! The needle is snappy, highly responsive, and remarkably accurate across typical daylight exposure scenarios.

Not only does my Konica IIIA now look effortlessly stylish with its period-correct German accessory, but I also have a fully functional, battery-free meter attached right on top of the viewfinder.

If you have a dead shoe-mounted Metraphot, Leica Meter, or similar vintage selenium light meter sitting in a drawer, don't throw it out—grab a cheap solar cell and give it a second life!

A Note on Linearity & The Sunny 16 Reality

It is worth noting that while a modern solar cell successfully revives the needle, its voltage response curve isn't perfectly linear compared to the original selenium cell designed for this specific galvanometer circuit. As a result, readings in extreme low light or harsh highlights can deviate by a stop or two.

However, even with these slight measurement inaccuracies, the Metraphot 2 remains an indispensable piece of kit. At the very least, it sits atop the Konica IIIA as a stunning, period-correct vintage ornament that honors the camera’s 1950s aesthetic. And when accuracy truly matters in tricky lighting, it serves as a fun sanity check while I rely on the ultimate, time-tested tool: good old Sunny 16 rule intuition and film’s generous latitude.