There are many ways to get the right exposure settings for the camera that does not have a light meter like Leica M2: the sunny 16 rule, the original Leica light meters, a phone light meter app, a traditional external light meter device, etc. Recently a new type of devices appeared: tiny set top boxes on the camera body itself that use a hotshoe slot.
Update: before jumping into the latest electronic light meters, let me remind you what Leica originally produced for cameras like M3 and M2 – Leica Meter MC.
My Leica MC came with M2, and it was not functional. This one is selenium-based. There is another type that is battery-based.
Back to the new shiny things. I got interested in such devices, and got one from eBay, just to try. It has one button and one joystick, and can be recharged via a USB connection.
This particular device uses continuous sampling mode. I don’t need to press a button to see the settings for the specific situation. I do need to turn it on.
The first thing I need to do is to set the ISO of the film that I have in the camera at the time. Then I can change the aperture and watch the shutter speed (aperture-priority mode) or I can change the shutter speed and watch the aperture (shutter speed-priority mode). When I turn the device off, it does remember the last settings.
The simple test of the device is to mount it on the digital camera, and compare the two. In my case, I used Leica Q. For some reason, given all the settings set to the same, the Leica Q meter was more sensitive. I assume the device was specifically designed to overexpose the film. This is actually a good thing since I prefer film stocks that are very forgiving and prefer to be overexposed – like Kodak Portra 400.
I had to change the mounting part to raise the device from the camera body, since it was blocking access to the shutter speed dial.
The whole setup looks funny, but it is functional and compact. I don’t need to use my iPhone app every time before taking a picture anymore. But I do miss the opportunity to take a snapshot of the app’s settings together with the frame and geospatial information. It seems like sometimes I will still use the phone app for that.
Update: there is a new light meter that fits better by color and by size to Leica M film cameras: KEKS EM-01 Light Meter.