The Leica M is one of the most recognisable camera systems ever made. From the original Leica M3 of the 1950s through to cameras such as the M6, M10 and M11, that single letter has represented Leica’s approach to photography for more than 70 years.
But what does the M actually stand for?
The answer is wonderfully German: Messsucher.
M stands for Messsucher
Messsucher is a German word describing a combined rangefinder and viewfinder.
Breaking the German down helps explain it:
- Mess relates to measuring.
- Sucher means finder or viewfinder.
- Messsucher therefore describes a viewfinder that also measures distance.
And that’s exactly what happens when you focus a traditional Leica M.
Rather than looking through the camera’s taking lens or relying on autofocus, you’re looking through a separate optical viewfinder containing a mechanical rangefinder.
It’s such a fundamental part of the camera that it gave the entire system its name.
So, what exactly is a rangefinder?
If you’ve grown up using SLRs, DSLRs or modern mirrorless cameras, a Leica M can initially seem slightly strange.
With an SLR, light travels through the lens and is reflected by a mirror into the viewfinder. With a modern mirrorless camera, the sensor effectively shows you what the lens sees through an electronic display.
A traditional Leica M does neither.
Look through the viewfinder and you’re essentially looking straight through the camera through a dedicated optical window.
The lens isn’t providing the image you’re seeing.
Instead, bright lines – known as framelines – appear inside the viewfinder to indicate approximately what your attached lens will capture. Leica’s current rangefinder M cameras display these in pairs for 28/90mm, 35/135mm and 50/75mm lenses.
This is also why you can see outside your photograph when using a Leica M.
With a 35mm or 50mm lens, for example, your framelines sit within a larger optical view. You can see what’s happening beyond the edges of your photograph.
For street and documentary photography, that’s incredibly useful.
You don’t simply see someone once they’ve entered your composition. You can see them approaching the frame, anticipate where they’re going and release the shutter at precisely the right moment.
It’s one of those characteristics of a Leica M that sounds relatively insignificant until you actually start using one.
Sometimes the rangefinder needs adjustment.
But if you’re not looking through the lens, how do you focus?
This is where the Messsucher part comes in.
Look through the viewfinder of a Leica M and you’ll notice a small, bright rectangular area in the centre.
That’s the rangefinder patch.
When your subject isn’t in focus, you’ll effectively see two slightly displaced versions of it inside that patch.
Rotate the focusing ring on your lens and one image moves across the other.
When the two images perfectly overlap and become one:
You’re focused.
There is no green confirmation box.
No autofocus beep.
No focus points to move around the screen.
You simply align the two images.
Leica calls this the superimposed image or double-image method. The system can also be used as a split-image rangefinder by lining up a clearly defined vertical edge.
Once you understand what you’re looking for, focusing becomes surprisingly intuitive.
How does the Leica rangefinder actually work?
The clever part is that your Leica is effectively looking at the subject from two slightly different positions.
One image comes through the main viewfinder.
A second image enters through the smaller rangefinder window on the front of the camera.
Inside the camera, that second image travels through a mechanical optical system containing lenses, prisms and mirrors before being superimposed over the main viewfinder image in that little central rangefinder patch.
This creates the double image you see when the lens isn’t correctly focused.
Now rotate the focusing ring.
The M lens mechanically communicates its focusing distance to the camera through a cam on the back of the lens. That cam interacts with the camera’s rangefinder mechanism, changing the angle of the rangefinder optics as you focus.
The two images consequently move relative to one another.
When they coincide, the geometry of the rangefinder mechanism corresponds with the distance at which the lens is focused.
In other words:
Two images = out of focus.
One perfectly aligned image = in focus.
It’s an elegant piece of mechanical engineering.
And unlike autofocus, the basic principle doesn’t require the camera to electronically analyse the scene and decide what should be sharp.
You make that decision.
How to focus a Leica M
Using it is considerably easier than explaining the engineering behind it.
Imagine you’re taking a portrait with a 50mm lens.
First, bring the camera to your eye and compose roughly using the 50mm framelines.
Now look at your subject’s eye.
Move the camera slightly so their eye sits inside the rectangular rangefinder patch in the centre of the viewfinder.
If the lens isn’t focused on their eye, you’ll see something resembling a ghost image – two eyes or two outlines slightly offset from one another.
Turn the focusing ring.
You’ll see those two images moving towards or away from each other.
Keep turning until:
eye + ghost eye → one eye
That’s your focus point.
You can then hold that focus distance, recompose the photograph if necessary and press the shutter.
Leica specifically recommends using contours such as the eyes when focusing portraits with the double-image method.
The split-image technique
There’s another useful way to use the rangefinder.
Instead of looking for two complete images, find a strong vertical line.
That might be:
- the edge of a building
- a door frame
- a lamp post
- the edge of someone’s clothing
- another clearly defined vertical feature
Place that line through the rangefinder patch.
When you’re out of focus, the line will appear broken or offset within the patch.
Rotate the focusing ring until both sections line up perfectly and appear as one continuous line.
You’re focused.
Leica’s own M11 instructions recommend precisely this technique for subjects such as architecture.
You don’t move the focus point
This is another major difference between a Leica M and a modern autofocus camera.
The rangefinder patch stays in the centre.
You can’t move it around the viewfinder with a joystick.
If you want to focus on someone’s eye positioned on the left side of your composition, you generally:
Point centre at eye → focus → recompose → shoot.
It can initially feel primitive compared with a mirrorless camera offering hundreds of autofocus points and automatic eye detection.
But after a while, it becomes extremely fast.
Your left hand controls the focus ring while your right hand controls the camera. You’re watching the subject rather than watching autofocus boxes move around a screen.
What happens inside the lens when you focus?
There are actually two things happening simultaneously.
When you rotate the focusing ring:
1. The lens elements move to change the optical focus.
2. The lens mechanically tells the camera’s rangefinder what distance you’ve selected.
That second part is important.
The rangefinder isn’t looking through the lens to determine whether the resulting photograph is sharp. Instead, the mechanical coupling between the lens and camera allows the rangefinder mechanism to correspond with the distance at which the lens has been set.
It’s why calibration matters so much with rangefinder cameras.
The camera, lens and rangefinder mechanism all need to agree.
Why rangefinder focusing can be incredibly fast
Manual focus sounds inherently slower than autofocus.
Sometimes it is.
But a skilled Leica M photographer can focus extraordinarily quickly because you don’t necessarily need to start from scratch for every photograph.
Look at many Leica M lenses and you’ll find a focusing tab underneath the lens.
With experience, the position of that tab can tell your fingers roughly where the lens is focused without even looking at the distance scale.
You begin developing muscle memory.
You can also pre-focus.
If you know someone is about to walk past a particular doorway, for example, focus on the doorway before they arrive.
Wait.
They enter your frame.
Click.
There may be no need to focus at the decisive moment at all.
Zone focusing takes this even further
Rangefinder photography also lends itself beautifully to zone focusing.
Instead of focusing on one exact subject, you deliberately choose a distance and aperture that gives you an acceptable range of sharpness.
Suppose you’re photographing on the street.
You might set the lens to approximately three metres and choose a smaller aperture such as f/8.
Using the depth-of-field markings on many M lenses, you can estimate the range of distances that will appear acceptably sharp.
Now you don’t necessarily have to use the rangefinder for every photograph.
When something happens within your predetermined zone:
Raise camera → compose → shoot.
This was particularly valuable for generations of documentary and street photographers working before autofocus, and it remains useful today.
What about parallax?
There’s another interesting consequence of the Leica M’s design.
Because the viewfinder and taking lens are physically in different positions, they don’t see the scene from exactly the same angle.
This difference is called parallax.
At long distances it makes very little practical difference, but it becomes increasingly noticeable as you move closer to your subject.
Leica compensates for this mechanically. As you change focusing distance, the bright-line frame shifts within the viewfinder to compensate for the difference between the position of the viewfinder and lens. Modern M cameras therefore provide automatic parallax compensation linked to focusing distance.
Again, it’s happening largely without you having to think about it.
Why not just use autofocus?
From a purely technological perspective, autofocus is easier.
A modern mirrorless camera can detect a person’s face, find their eye, track them as they move and continuously adjust focus faster than a human photographer could reasonably hope to.
The Leica M doesn’t try to compete with that.
The appeal is different.
Rangefinder focusing makes distance part of the photographic process.
You begin thinking about whether your subject is one metre away, three metres away or ten metres away. You learn the movement of your lens. You learn how depth of field changes with aperture and distance.
Eventually, you can find yourself adjusting focus before you’ve even brought the camera to your eye.
The camera becomes less something that makes focusing decisions for you and more a mechanical tool responding directly to your hands.
Why can you see outside the photograph?
This remains one of the great advantages of the rangefinder.
Because you’re not looking through the taking lens, the viewfinder can show an area larger than the photograph itself.
Leica specifically identifies this as one of the advantages of the system: photographers can observe what’s happening immediately outside the framelines and anticipate something entering the composition.
It’s particularly suited to street photography.
Instead of chasing the subject with the camera, you can compose first and wait for the photograph to happen inside your frame.
The Leica M began with the M3
The Leica M story began in 1954 with the Leica M3.
The M3 brought together the M bayonet mount and Leica’s combined viewfinder/rangefinder concept in a form that established the basic architecture of the M system.
What is remarkable isn’t simply that Leica invented this system.
It’s that the fundamental idea has survived.
An M3 from 1954 and a modern digital Leica M are obviously vastly different cameras. One exposes film mechanically; another contains a high-resolution digital sensor and sophisticated electronics.
But put either to your eye and the fundamental process is immediately recognisable.
Look through the optical finder.
Find the rangefinder patch.
Rotate the lens.
Bring two images together.
Compose.
Press the shutter.
More than just a letter
So if you’ve ever wondered what the M in Leica M stands for, the short answer is:
M = Messsucher = rangefinder.
But knowing what Messsucher means tells you considerably more about the Leica M than simply explaining its name.
It explains the entire philosophy behind the camera.
A Leica M doesn’t automatically decide where you should focus. It doesn’t normally hide the world outside your composition. It doesn’t require you to navigate focusing modes or select from hundreds of autofocus points.
Instead, you’re given a window onto the scene, a frame showing where your photograph will be, and two images that you bring together with your own hand.
It’s mechanical, remarkably precise and almost completely unchanged in concept since the 1950s.
And perhaps that’s why the M still means something more than 70 years later.
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