After venturing back into a world of large format photography ten years ago, I had to step back and learn how to use a light meter with accuracy. I went through a few vintage spot meters before I settled on a Sekonic D-758, a modern and rather complex tool with a huge array of functions and shortcuts to memorise. Fast forward ten years, and just three film cameras out of the nine that I own have a built-in light meter.

One of those was sold to me as ‘working’ from a seller in Japan and you guessed it, it doesn’t work. For the modern digital photographer stepping back in time on a first nostalgic journey, this disarming predicament can feel rather uncomfortable. A separate light meter means more clobber and a creative disconnect from the romance of that first ‘decisive moment’. Something smaller and simpler is needed. Now thanks to modern battery technology, clever aluminium machining and circuit boards the size of your thumbnail, our dreams have come true.

Keep It Simple

So what functions could we do with? Aperture Priority please, that’s literally all I need. But let’s get a few things straight. These meters like the Keks KM02 and Doomo Meter S that I primarily use on my 35mm Canon rangefinders (and even a Mamiya 645 1000s) are very straightforward and really look the part.

The Keks KM02 measures roughly 42 × 27 × 15mm and the Doomo Meter S is similar in footprint, its anodised aluminium body matching the industrial lines of classic rangefinders. Both use bright OLED readouts that remain visible in daylight. This design makes them ideal companions for Leica Ms, Canon P‑series (or the Canon 7s / VT Deluxe in my case) and especially the popular Nikon F cameras. The main draw is that they add functionality without disturbing the profile of the camera. I like to think this extra brain was in the post from design stage, an intentional vintage firmware update, shall we say.

The Keks’ 30‑degree metering angle corresponds to a normal 50 mm lens on full frame. It employs the VEML7700 16‑bit sensor, allowing exposure accuracy even under strongly back‑lit or mixed‑light conditions. It operates across ISO 50–102 400, apertures or f/1 to f/128,  and shutter speeds from 1/8000 s to 30 seconds, all selectable via single‑ or continuous‑metering modes. Doomo’s OLED meter covers the same exposure span (EV 1–22 approx.) offering real‑time metering that instantly updates as you pan the camera. It’s a real joy and you feel ready to shoot.

I tested all of them against my Nikon F2AS with a DP12 meter, as well as a Gossen Lunasix F. The Doomo / Keks and the Nikon gave consistent accuracy and the Gossen I now realise is measuring everything one stop under. I now need to investigate why this is.

Ease of Use

For digital photographers transitioning to film, usability is paramount. Both meters adopt minimalist interfaces and the design is thoroughly well thought out. The Doomo Meter S has one dial and a single button: set your film’s ISO, choose an exposure mode, press to sample or lock an EV reading. Double press and switch between aperture or shutter priority. Its design reduces the learning curve yet demands a little muscle memory to recall which press‑and‑hold combination is needed. The Keks DM02 introduces two tactile buttons at the top, one for function, another for metering, whichallows faster recall once memorised. Both are easy to use once the path has been walked a few times.

Each meter’s OLED is a delight. The displays are small and well defined but under my testing this summer, the screens can appear a little faint until shaded by my hand. The Keks screen is facing the eyes, the Doomo is on the top, which I personally think makes the Keks faster to use. The Doomo’s dial feels smooth but lacks detents, which is understandable, but this means it’s not so easy to be precise.

Internally, both devices draw power from a tiny built‑in lithium‑ion cell (I am amazed at how these are built) and both come with the convenience of USB‑C charging. This morning it took just 20 minutes to charge from 10 to 100% using a power bank. From some online research, the Keks lasts around  21 hours of active metering per charge and the Doomo can go weeks between top‑ups due to low idle consumption. Taking that first shot only to find your mercury cell meter batteries are flat is now a thing of the past, as most of us carry portable power these days. Isn’t it amazing how far we have come?

Practical Training

Having a meter like this, that you can literally lose in your jeans pocket, means you can use it as a metering training aid. Set it up and walk around trying to guess the shutter speed. It’s a fun game that for some strange reason I just can’t get my wife Rachel to play.

The great thing about these tiny portable meters is that you can migrate them to any system you like, which means you’re encouraged to dig out dad’s dusty camera and take it for a Sunday drive. No need to pack yet another case, or an inaccurate vintage leather-cased relic and incident dome, with dangling cables and dubious results.

Final Thoughts

These convenient and accurate tools are not designed to compete with a 1º accurate spot meter like the Sekonic I mentioned. They are functional and dare I say it necessary accessories for the modern film enthusiast, especially the 35mm photographer with a 35mm or 50mm prime. They align with a subtle aesthetics when mounted on top of a mechanical classic. Both are small enough to lose (so watch out for that), so I have left both in place on my 1950’s Canon rangefinders for now.

The price is far less than many other modern digital meters (around $100 to $130 respectively) and also competes with a second-hand vintage meter like the Gossen, which as I found out may be less reliable. Although they initially appear rather small, the Keks or the Doomo are tactile, engaging and a relief to use.

Whether a seasoned film photographer or a digital photographer alike, they represent how our wonderful world of modern technology is supporting classic cameras for generations to come.

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