This is my personal opinion ;)
Have you wondered what is the best pocket light meter, the one that does not slow you down?
A light meter that is accurate most of the time and modern enough to be selenium-free…
The answer: Sekonic L-136 Micro.
It is a small shoe mount CdS light meter, that is relatively inexpensive, but very accurate.
Of course, it uses the dreaded mercury PX625 battery. In my case, I have installed Stable625 voltage regulator in it and now it runs off a normal SR44.
What is more, I left the battery in for a year and there is no measurable voltage drop or change in performance.
As I mentioned, Stable625 is very small. You can see it here installed, held in place by the sheer thickness of wiring and covered in hot glue to prevent any electrical shorts. In this setup, you want to have a separate wire from the battery positive side to the voltage regulator, and ensure that battery + side is not touching the enclosure. Normally, the chassis is positive. Utilizing Stable625, the voltage regulator input is black that goes into the battery compartment and makes contact with battery positive terminal; output is yellow that is soldered into a common positive point on the light meter circuit; and blue is ground.
Following these connections, the meter still retains its function, drawing from voltage regulator only when the measurement button is depressed. Even battery check works, although it’s not accurate I believe.
How to solve the battery terminal issue? I 3D printed a PX625 to LR44 battery adapter and made a hole in the side for the wire. This way, the battery negative terminal touches the negative terminal in the battery compartment, while the battery positive terminal touches only the wire. The wire is the black wire depicted below, that goes into the “IN” side of Stable625 voltage regulator. This way, we have a stable 1.35V on the output.
This is the bottom of Sekonic Micro. You can see the white plastic battery adapter with a thin insulated wire. No battery was installed at the time of taking the picture.
Okay, where does Sekonic stand among other shoe mount meters?
Above you can see a comparison of 3 shoe mount light meters: Metraphot 3, Sekonic L-136 Micro and TTArtisan. One dime coin for scale.
Surprisingly, Metraphot is still accurate, but only in daylight. This will likely change over time. Sekonic is accurate in a wide range of light, while TTArtisan is most accurate of them all, being the most modern.
Having said that, I don’t like TTArtisan. With Sekonic, I press the button once, set the readout EV number on the wheel and I can appreciate all f-values and shutter speeds at once, making my choice easier. With TTArtisan, I have to scroll through either speeds or f-values until I get a green light, and then I am presented with only 3 speeds for immediate reading. On top of that, this light meter does not go past f/22, which may be an issue with medium and large format. Sekonic goes to f/32 .
Incident metering? Yes, there’s a small chain with light diffuser. I don’t use that since I have a real-deal incident meter, and still rarely use it. It’s less accurate in my opinon than reflective metering.
Accuracy? All three meters pictured above are spot on during daylight. Sekonic did not need any adjustment after installing Stable625 inside. The installation took about 30 minutes.
In my other Sekonic L-136, I had to drill out one of the set screws for the “High-Low” switch. The previous owner damaged the screw head and decided to superglue it in. I have rethreaded the plastic hole and installed a new set screw from Japanese company Del-Screw, which I highly recommend.
You can purchase Stable625 1.35V (or 2.7V) voltage regulators by emailing me at stable625px at gmail