Decent Exposure Part 1: Attachable external light meters and where they help

They seem like relics from a remote past. But an external light meter is more important than you might think. In “decent exposure”, a small series of three articles, we compare a total of 15 different light measuring solutions from the legendary Leicameter MR to the latest smartphone app. Let’s set off with Voigtländer, TTArtisan, KEKS, Hedeco and the good old Leicameter: A review of five attachable light meters.

It’s an accessory that was about to be forgotten by most photo amateurs. With the triumph of the digital camera, the challenge of precise light metering seemed to be over. When sheer quantity causes no extra cost, you can excessively use exposure bracketing and just keep the best version, can’t you? And on-the-spot control of the just-taken image spares you the nervous moments of looking at your processed images for the first time. Finally, all modern cameras offer precise histograms, many even in live view. So why should exposure metering be an issue at all? 

But hold on. Our review of five attachable light meters, five hand-held meters and five apps will show you why there are still quite a number of exposure meters being manufactured. They wouldn’t be if there were no demand, I believe. And indeed, there are situations when you still need a dedicated device for your correct exposure. Three articles in our mini-series will be about some of these use cases. And I will introduce you to fifteen different ways to work your way through the issue. 

This first article of the series comprises small reviews of five light meters that can be attached to your camera via its accessory shoe: Leicameter MR, Voigtländer VM Meter II, KEKS EM-01, TTArtisan Two Dials Exposure Meter and Hedeco Lime One.

Five more light meters that I will be covering in the second part of the series are hand-held devices from various generations: Gossen Lunasix F and Variosix F, Sekonic L-758D, L-398A Studio Deluxe III and L-208 Twinmate.

In the third part, I will look at five popular smartphone apps (iOS) that can serve as light meters, MyLightmeterPro, Photometer, Lghtmtr, Luxi and Lightmate; additionally, I will give a full concluding overview including a large comparison table in the third and final part.

As the attachable meters are only designed for object metering (measuring reflected light), I will give some basics about this method in the first part. The second part will add incident light metering because this is the true domain of the hand-held meters. If you are – and I expect this applies to some of you – familiar with all the basics, you might want to jump right to the review section in each of the three articles. In this first instalment, be ready for a review of five attachable light meters.

Why an external exposure meter?

The first reason to use an external exposure meter is quite obvious: Your camera has no built-in light meter or the built-in device is out of order. Many iconic cameras have no built-in light meter. A lot of the mechanical bodies from the 50s, 60s and even 70s are lacking this little electronic aid. Take for example the Leica M3, M2, M4 or the Hasselblad 500C. With the film renaissance, many of these cameras are seeing use again. But many of their users are not experienced or audacious enough to guesstimate correct exposure. 

Other cameras have a built-in meter for TTL measuring but it’s not working anymore. This can be due to electronic (ageing selenium cells) or mechanical (the notorious cable in the Plaubel Makina 67) failures, or it’s due to the fact that the required batteries for your camera are no longer available. The Leica CL, Leica M5, Olympus OM-1 and Minolta STR all need the V625PX button cell with a 1.35 Volt rating. These were mercury batteries that are no longer being made for ecological reasons. There are some workarounds, but a proper replacement does not exist. So you might well end up needing a light meter.

Attachable meters: A long legacy and finally a renaissance

An attachable exposure meter has been a solution for meter-less cameras for a long time. It is mounted to the accessory shoe of your cameras and points in the direction in which you are shooting. Thus, it will always measure the light that is actually reflected by your subject. In this respect, it works the same way as the built-in through-the-lens metering of a camera but with the disadvantage that you have no perfectly precise control over the area of measurement.

Any exposure setting based on reflected light has the inherent disadvantage that your meter can’t “know” if your subject has the standard distribution of bright and dark areas to which the device is adjusted. This is normally 18 per cent grey. Obviously, a sun-lit snowy winter scene is much brighter, and a matte black steam locomotive is much darker. This is where the knowledge of the photographer matters – especially if you can’t directly check your results because you are working on film.

Within these limitations, attachable meters are utterly practical and that’s why they once were very popular. Leica for example started offering this accessory from 1950 and thus before the M system was even introduced. From early insensitive and inaccurate selenium cells to more modern CdS (cadmium sulfide) there were several steps of improvement. The so-called Leicameters were, by the way, not produced by Leica themselves but by Metrawatt in Nürnberg.

After the discontinuation of the Leicameter (the M4-P went out of production in 1987, and the subsequent M6 had its light meter finally built in) there seemed to be just no need for attachable meters. But I think it was with the analogue renaissance that Voigtländer started to make the VC Meter. Later, other projects were launched, some of them following the rather classical style, others very modern with OLED displays. Unfortunately, I know of no modern product that offers the elegant mechanical coupling with the time setting wheel on an analogue Leica M. In this respect, the Leicameters remain unmatched.

Get the details – five solutions that might fit you

Here we go with the review part finally. Any of these items would deserve an in-depth article for sure, but I will confine myself to an overview. Additionally, I will link to some existing reviews that I found helpful. And please keep in mind that your user experience might be quite different from mine. I am sharing knowledge, experience and opinion here but I do not by any means claim to teach you the ultimate truth.

Most of my knowledge about the five meters that will be reviewed below comes from practical use. Sometimes, the original manuals were also very helpful. Furthermore, I want to recommend 35mm.com which is a great photography-related project and an excellent site to browse. Editor Hamish Gill also worked on the subject of shoe-mount light meters. Had I known earlier, I probably would not have started my writing at all. But now I can gladly recommend you this second opinion that I personally only discovered when my text was almost finished.

Read on for the review of five attachable light meters.

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Leicameter MR

For Leica, it was clear early on that if you wanted to sell a precision instrument, you could not rely on mechanical and optical excellence, but had to provide a solution for all parameters of photography. So as early as 1950, a few years before the introduction of the M system, the first attachable light meter came onto the market. And it came with a feature that was to remain the unique selling point of the Leicameter until the end. This smallish device couples mechanically to the shutter speed wheel of the camera. The measuring, reading and setting of the exposure time are thus combined in one action. This was a phenomenal idea at the time and it still is today, in its ingenious mechanical implementation.

Out of the several Leicameter generations, I am describing here a late model, the Leicameter MR. It already has a CdS measuring cell that works far more precisely and allows a much wider measuring range than the earlier selenium cells, but it needs a battery for that, and that’s where the problem begins. The 1.35 V mercury cells have been discontinued for a long time. Today’s Weincell batteries with the same nominal voltage unfortunately do not last long. But there is a solution: The small company Knoch Messgeräte in Schwarzenbruck near Nürnberg can repair these classics to this day and also converts them to 1.5 volts.

If you have managed to connect the Leicameter to the camera (if German is okay for you, you can download an instruction manual here or for an English version visit Mike Butkus – don’t forget to leave him a tip), you don’t have to think long about how to operate it. The measuring range roughly corresponds to the viewfinder section for the 90-mm lens, so we get a kind of moderate spot metering at the classic Leica focal lengths of 35 and 50 mm. 

Set the aperture you want to use, point the camera at the subject, store the exposure with the button on the Leicameter and read by means of the graphically shown channels which time you have to set. Or select the exposure time you want to use and read the aperture. That’s it. If you have to increase by, say, two EV steps due to the use of a yellow filter, set a correspondingly lower ISO number or keep the pointer in the plus range accordingly. 

With a well-calibrated Leicameter and some basic knowledge of exposure techniques, it is not difficult to get correctly exposed negatives. With more demanding slide film, the measuring and operating tolerances of my Leicameter would be a little too high for me. But apart from that, this little accessory, once manufactured by Metrawatt, is a superb device. Whether it gives the camera an even more classic look or makes the Leica M look a bit chunky is something everyone has to decide for themselves… 

Before we continue with the review of attachable light meters, here we go with some links related to the Leicameter:

https://www.youtube.com/watch?v=qIxnu0YKu-U – No comment about the video itself, but it shows how to attach the Leicameter and how to open the battery compartment

http://reinhardt-claus.de/LeicaMeter/Leicameter%20MR.pdf – Instruction manual in German, Claus Reinhardt has many more useful documents on his site

https://www.roter-punkt-kamera.de/leicameter/ – German, a good overview of the different types of the Leicameter

http://www.knoch-messgeraete.de/leicameter.htm – Here you can get your Leicameter repaired and serviced, including 1.5 Volt conversions

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Voigtländer VC Meter II

For a long time, after the Leicameter was discontinued, there was no attachable exposure meter to be bought new. Most M3s, M2s and M4s probably slumbered in drawers and showcases in the 90s and 00s. But once again Cosina/Voigtländer had the right instinct and brought the VC Meter Version I to the market: A beautifully crafted metal housing with one dial each for exposure time and aperture and an LED display.

Nothing much has changed with version II, except that the dials are no longer half on top of each other, but neatly arranged next to each other. In one dial you can preset the film speed, and there is exactly one orange (wouldn’t red have been much nicer?) button to activate the metering and then save it at the same time. 

On this basis, you take the camera from your eye and select a combination that illuminates the green LED in the middle. If one of the two red arrow LEDs on the side also illuminates, you are half a stop above or below the standard value. If only one of the red arrows is visible, the deviation is a full f-stop or more. The discs are conveniently arranged in such a way that you simply have to turn one or both of them in the direction of the arrow. If you want to measure continuously, simply keep the button pressed.

The aperture wheel is continuously adjustable (this makes sense since Leica and Voigtländer lenses have half aperture stops, Zeiss lenses even one-third aperture stops), while the shutter speed dial locks at full values. If you have a very old M with the early shutter speed sequence 1/5, 1/10, 1/50, 1/100, you have to correct a little with the aperture or rely on the exposure margin of the film.

All in all, the VC Meter is a beautiful device, also thanks to its simple and Leica-like design. It looks very well made and reliably delivers precise metering results. It is available in silver and matte black, and you can choose according to the camera you use (black is perhaps a little more universal). 

All well and good — if it weren’t for the price of almost 300 euros, for which there is hardly any other word than outrageous. Until a few years ago, you could get a Leica — not in collector’s condition, but in working order — for a little more than the current price of this small exposure meter.  I purchased the VC Meter II some years ago at the Leica Store Konstanz.

Before we continue with the review of attachable light meters, here we go with some links related to the VC Meter II:

https://www.35mmc.com/15/01/2015/the-voigtlander-vc-meter-ii-light-meter-review/ – A very competent review on a great site

https://richardhaw.com/2018/03/21/review-voigtlander-vc-meters/ – Good comparison between the first and the second version of the VC Meter

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TTArtisan Two Dials Exposure Meter

And perhaps it was precisely the more-than-hefty price tag of the VC Meter II that set the TTArtisan people in China off on a mission. Maybe there is also a connection with crowdfunding projects like Reveni. Maybe it all came about completely independently, and it just happened that the TTArtisan Two Dials Exposure Meter looks very, very similar to the one from Voigtländer. As the name suggests, it has two dials and also works with three LEDs.

The function of the TTArtisan is exactly the same as the Voigtländer. Here, too, there are f-stops from 1 to 22 and exposure times from 1 to 1/2000 second. Here, too, a button activates the exposure metering, which is then immediately saved. In a window, a green LED in the centre and two red ones on the sides indicate the exposure. The only difference is that there are no arrows on the left and right, but a plus and a minus. Unfortunately, as with the Voigtländer, the ISO setting easily misaligns itself because it does not lock in place and is very sluggish. 

The measurement results of the two light meters are very similar, they could be reproduced in different lighting scenarios with different light sources and they were close to the measured reference value. With the TTArtisan you will possibly get slightly stronger exposed negatives, but this is all within a tolerance of less than half an f-stop. 

So where are the differences? The Voigtländer exposure meter needs two SR44/LR44 batteries, the TTArtisan a single CR2032 lithium cell. The VC Meter uses easy-to-read, classic typography reminiscent of the standard Leica typeface of the 1950s to 1970s, the TTArtisan closely follows the current Leica typeface (LG 1050) and is not quite as easy to read (at least in black compared with the silver of the VC Meter). And the TTArtisan has a very unobtrusive round measuring button, while that of the Voigtländer is strikingly orange and square. 

Also, changing the battery on the TTArtsian is a fiddle with a tiny Phillips screw that half holds the battery cover. With the Voigtländer, no tools are needed to change the batteries, but the door of the battery compartment could wear out quickly. And another difference: while the VC Meter is wonderfully flush with the body of an M3 at the front, the TT Artisan protrudes a few millimetres over it. That does look a little inelegant.

All in all, however, there is not much to say against the TT Artisan light meter. Rather, the price — a quarter of what Voigtländer is asking — speaks very clearly in favour of the Chinese version. The light meter looks very well made; apart from silver and matt black, it is also available in black paint with pre-programmed wear. I got mine from Jo Geier Mint&Rare in Vienna for around 70 euros.

Before we continue with the review of attachable light meters, here we go with some links related to the TTArtisan light meter:

https://style.oversubstance.net/2021/12/review-of-the-2-dial-ttartisan-light-meter/ – Includes a comparison with the Voigtländer VC Meter

https://www.35mmc.com/18/04/2022/ttartisan-light-meter-review-the-cheapest-of-its-kind-by-frankie-bina/ – Another competent review

https://www.macfilos.com/2021/10/27/new-tt-artisans-lightmeter-comes-in-at-under-50/ – Announcement and technical data

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KEKS EM-01 Light Meter

Compared to the almost historical Leicameter and the retro Voigtländer and TTArtisan attachable light meters, the KEKS EM-01 follows a radically different and very modern approach. What it has in common with the other three exposure meters is the fact that it is also a small device. But instead of rotary dials with engraved labelling, there are only push buttons without any labels. And the result is not displayed via a LED light balance but on an OLED display.

The manufacturing leaves a very good impression. Even without labelling, the keys are very easy to operate. The rear button activates and saves the measurement. The pair of buttons at the top left is for setting the aperture in one-third steps (front button for larger aperture or more saturated exposure). The pair of buttons at the top right is for setting the exposure time according to exactly the same logic. All values of the historic Leica shutter speed sequence can also be set, which is a real plus.

All this is shown on a beautiful, high-contrast OLED display in bluish-white lettering on a black background. In addition to exposure time and aperture, the selected ISO value (set with the left buttons plus the metering button) is also displayed, as well as the exposure in EV values and in lux. You don’t really need the latter for photography, and filmmakers will hardly use the KEKS because it can only measure reflected light and not incident light.

You don’t have to replace a battery on the KEKS because it is charged via a USB-C cable and should then be ready for use for up to 20 hours. It is more likely that the shoe mount will have to be replaced because it is made of cheap plastic. There is probably a reason why a replacement part is included right away. You can order an aluminium plate for this purpose directly from the manufacturer. Given the price of the KEKS, they could have included it at no extra cost.

The metering results were consistently a little tighter than those of the other two modern attachable light meters, by about half an aperture. Those who shoot on slide film may be quite happy about this. On negative film, it could be that the film is minimally underexposed However, the tolerances in the lab will be wider anyway, and I could not find any problems in my tests on film.

The China-made KEKS is available in black and silver for just over 150 euros, thus ranking between the TTArtisan and the Voigtländer. This seems justifiable to me because the features, including the OLED display, are really good. By the way, I think it’s great that the display is built-in at the back, towards the photographer, and not at the top like on the Doomo light meter, for example. For those who don’t need a retro feeling when measuring exposure, the KEKS will be a real treat (pun intended: Keks means biscuit in German). I got my own one from Fotoimpex in Berlin.

Before we continue with the review of attachable light meters, here we go with some links related to the KEKS:

https://www.35mmc.com/19/04/2021/keks-em-01-shoe-mount-light-meter-review/ – Another very good review that shows why the site has such a good reputation

https://www.japancamerahunter.com/2021/10/review-keks-em-01-light-meter-2021/ – Very comprehensive and competent

https://www.bonnescape.info/test-erfahrungsbericht-aufsteck-belichtungsmesser-keks-em01/ – A good review in German

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Hedeco Lime One

This thing indeed gives a few vibes. The Hedeco Lime One is the result of a crowdfunding campaign on Kickstarter. Its inventor Johannes Heberlein is young enough to have newly discovered the world of analogue photography. The small attachable light meter comes in a beautiful retro Wirtschaftswunder[footnote]The period of the post-war German Economic Miracle[/footnote]packaging. But: it is much more than a chic accessory. The LIght MEter one of the HEberlein DEsign COmpany is a full-featured and very cleverly designed attachable light meter, in which a more classic handling concept and a modern OLED display complement each other wonderfully.

The Lime One is so small that you’re surprised that it both fits the 2032 battery and offers a display. It weighs only 16 grams, which perhaps contributes to the fact that the device appears somewhat delicate (not to say fragile). However, the manufacturing quality seems very good, and the accessories produced with the 3D printer are also impressive. In addition, the order and delivery went very quickly. So that’s all great.

The Lime One’s operation is convincing. Not only does it master time and f-stop preselection, but also allows the setting of both parameters and the use of a light balance that shows deviations of up to three f-stops in one-third steps. I have never seen this with any other attachable light meter. The direct EV display is also great, especially since some cameras require or allow exactly this setting (e.g. Zeiss CF lenses for the Hasselblad 500). Although the display is very small, it is bright and has a beautiful fine resolution, making it easy to read in any light.

The range of functions of the Lime One is much greater than one would expect given the only two operating elements (one wheel, one button). A lot of brainpower has gone into this, compliments to Johannes Heberlein! At the same time, you never really need the manual if you just remember that (a) the control wheel takes on a second function when the button is pressed and that (b) double-clicking the button calls up the menu. That’s all it takes. Impressive!

The measuring accuracy of the Hedeco Lime One seems to be very good. According to the manufacturer, the measuring range starts at a record-breaking EV -3, although full accuracy is only available from EV 0 (which is still very good). The Lime One can furthermore be switched between continuous measurement and memory mode, which is also very useful in practical use. 

This little gem is not cheap, and compared to the similarly priced KEKS, the Hedeco does not ooze quite as much solid quality. Nevertheless, it is definitely recommendable for all those who are looking for an exposure meter with OLED, who want a high range of functions and who appreciate the operation via a jog dial. And the Lime One also has a bit of a historical vibe – Johannes Heberlein is based and produces the product in Nuremberg, exactly where Metrawatt manufactured the Leicameter for decades. You can buy directly from him.

Before we finish the review of attachable light meters, here we go with some links related to the Hedeco Lime One:

https://www.35mmc.com/07/10/2020/hedeco-lime-one-light-meter-review/ – Again, a great review on this great site

https://austerityphoto.co.uk/light-engineering-hedeco-lime-one-review/ – Interesting comparison between the Reveni light meter and the Kickstarter phenomenon

https://www.apertureonepointfour.com/hedeco-lime-1 – With unboxing video if you like that kind of stuff, in German

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Conclusion and Outlook

For general photography, any of the five attachable light meters will do the job. In any case, you will have to use your knowledge and experience to retrieve and evaluate the meter readings – and to correct them if necessary. A grey card can be helpful for very bright or very dark subjects. As a side effect, you will pretty soon get a good feeling for exposure – especially if you get into the habit of predicting your exposure and comparing that to the measured values.

Which of the five meters is the most recommendable is hard to say. The Leicameter might fit the purist approach best, and if you have a well-kept one, my advice is to have it serviced and adapted to modern 1.5 Volt batteries. The KEKS and the Hedeco are the most modern offerings while the other two attachable light meters are simply good and very similar products albeit at two very different price points.

With these final thoughts, we are leaving the sector of the attachable light meters. Part two of our small series will cover some popular hand-held meters before we move to some interesting light meter apps for your iPhone in part three.

And one last word on where to buy. You know that my work for Macfilos is completely independent. I do not get any benefits from the manufacturers or dealers I mention. Most of the attachable light meters can be bought directly but keep in mind that direct sourcing from China can end in considerable taxes and duties. I, therefore, recommend Jo Geier Mint&Rare at Vienna with their wide selection of new and used exposure meters. I got the TTArtisan from there. 

What do you think? Do you actually use a light meter (hand-held or attachable) or a light meter app? Have you recently missed having one and in which situations? Or do you just work with the sunny sixteen rule for your work on film? Or are you fully digital, taking advantage of the refined metering option in current cameras plus the possibility of immediate checking your results?  Are light meters and incident light measuring something for nerds or is all this still important? Let’s discuss it here.

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Decent exposure: The Macfilos mini-series about light measuring solutions

Part 1: Why light meters are useful or necessary and which camera-attachable light meters are recommendable (with reviews of Leicameter MR, Voigtländer VC Meter II, KEKS EM-01, Hedeco Lime One and TTArtisan Two Dials exposure meter (you can read this article in German here on Messsucherwelt).

Part 2: Why incident light metering is better and what other advantages hand-held light meters have (with reviews of Gossen’s Lunasix F and Variosix 3 and Sekonic’s Twinmate L-208, Studio Deluxe L-398A, and L-758D (if you prefer this article in German, find it here on Messsucherwelt).

Part 3: How you can work with a light meter app for your smartphone and which chances and risks you have to know (with reviews of MyLightmeterPro, Lightmate, Lghtmtr, Luxi and Photometer). Plus: The complete overview of all 15 tested solutions (again, there is a German version on Messsucherwelt).

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