What makes Leica images so different?

Back in those days of film and when my older daughter was little, we used to play this game: I would through a stack of 35mm slides on a light table and asked her to choose which ones she liked the best.  Except for very rare instances, she would invariably choose pictures shot with either Leica M, or Carl Zeiss lenses. Clearly it was something about them that a nine-year-old child would notice, and so did I. Moreover, I could see a difference between Leica and Zeiss images, yet was not able to give a preference to either. It took me more than ten years, however, to figure out what it was exactly that sets Leica pictures apart from those taken with other lenses.

The reason why I found this phenomenon important is that, incidentally, a statistically unusually high number of the most famous images of the 20th century were taken with Leica M cameras. Another thing to keep in mind is that all those images (and many others, equally great Leica-generated pictures that simply were not lucky enough to appear on the “the best of the best” billboard) ended up being so great despite the seemingly not-so-user-friendly ergonomics of the rangefinder design. By that I mean that, unlike cameras that offer a through-the-lens viewing experience, the Leica M viewfinder does not offer a WSWG (what you see is what you get) capability. Not to mention lack of the autofocus, zoom lenses and fully automatic exposure modes.

Of course, thinking that Leica cameras had a magic “masterpiece” button, or trying to allege something like that would be nonsensical. Hence it must have been a more scientific, or at least logical explanation to that. I believe that this explanation does exist, or at least I have one that seems plausible to me. However, for those who are looking for one and only answer, I have bad news: there is none. Moreover, if a picture is taken with a Leica it does not automatically mean that it is going to have the Leica look. It can happen only in two instances: either when a photographer knows how to capitalize on unique Leica properties (yes, there are some), or when stars align (i.e., because of sheer luck). The reason is that Leica pictures look distinctly different from and, for the most part, superior to other images due to a combination of factors. Some of them, namely the notorious “Leica Glow”, distinctive rendering of out-of-focus areas at wide apertures and “popping” colors are easy to pinpoint. Others are not. Some are not even associated with optical properties of the lenses. We will explore them one by one, but before dissecting the Leica look, let us see what it is, what it is not, and what sets it apart.

First of all, the way Leica (and some Carl Zeiss) optics renders an image is not realistic. Why are they so pleasant to the eye? Because they are better than life. Let me explain. Do you remember your first experience with polarizing glasses? First you look at the blindingly bright sky with barely noticeable clouds, and then you put those RayBans on, and one of a sudden the sky is blue, and the three-dimensional clouds are full of intricate tonal variations, and you do not have to squint to see it all! Does it look realistic? Nope. Does it look believable? You betcha. It does, because it looks like you want it to look. We people are suckers for beauty. We want things to look nice, because it makes us feel nice. But what does “nice” mean in this instance? Just like with polarizing glasses we see more with less effort. Another, perhaps even more dramatic example is when you are through with a denial about not needing reading glasses. You put them on, and an avalanche of tiny detail nearly knocks you off your feet. Looking at a picture that possesses the Leica look is not dissimilar to a combined effect of polarizing and reading glasses: high contrast, an amazing level of detail where it is needed, pleasant softness in areas that do not require much attention and an ability to see the whole tonal range effortlessly. All these things make the picture look like it is three-dimensional, almost tactile. All you need to do is to reach inside and pick up an object that you like the most.

By the way, the difference between Leica and Zeiss images is that even though they all may look three-dimensional, the former seem deep, yet the latter are more like a flat surface with 3D objects on it.

So, what are those factors that make an image look in such a special way?

I will start with the obvious and progress to the nebulous.

Bokeh, Leica way

A fancy Japanese word “Bokeh” means nothing more than “an out-of-focus area behind the point of sharp focus”. Leica lenses feature very smooth and eye-pleasing bokeh with specular highlights rendered as round or close to round blobs of roughly uniform tone (look at the image below) when the lens is wide open. This type of bokeh is called neutral. Some lenses turn specular highlights into round shapes that are brighter in the middle and darker closer to the outside of the shape. This type of bokeh is called positive and looks pretty nice. It is actually a matter of personal preference, so disputing whether the neutral bokeh is better than positive is pointless. However, if blobs are brighter on the circumference than in the middle, it is called negative. Most non-Leica zooms and low-quality prime lenses are that way. An extreme case of negative bokeh is produced by mirror lenses known for their donut-shaped rendering of specular highlights. I have yet to meet a person who would find negative bokeh pleasant.

When the lens is slightly stopped down, another factor comes into play: the number of aperture blades and, consequently, the shape of an aperture opening. Leica lenses have at least nine aperture blades, which makes the iris nearly circular (although some lenses have purposefully curved blades that result in a round opening with sprocket-looking notches). The opening of the aperture with a lesser number of blades is of a polygonal shape. It does not necessarily make the bokeh bad: a famous Hasselblad Carl Zeiss Planar 80mm f/2.8 CF lens has only five aperture blades, yet its bokeh is one of the most beautiful ever.

The way out-of focus areas in front of the sharp object look differs greatly from bokeh and usually does not look nearly as pleasant. The reason is, the lens can be corrected for smooth out-of-focus rendering only on one side. With camera lenses it is traditionally done aft of the focused area, because usually the first plane is more important than further layers of composition. Projection and enlarger lenses are corrected in an opposite way. There are some notable exceptions, however. For example Carl Zeiss Distagon 55mm f/3.5 for Contax 645AF has equally beautiful OOF both in front and in the back of a focus point.

Another important distinction of Leica and Zeiss lenses is that they are capable of preserving tonal values of objects in the bokeh, especially in the higher tones. Lenses of lower quality usually blow out-of-focus highlights much more easily. The reason for that is higher dynamic range of German optics resulted from use of special glass formulations

A mystery of the micro-contrast

Leica optics, at least the current one, is very contrasty. What it means in simple terms is: on a picture of an object with a wide tonal spectrum, blacks look black and whites look white.  However, there are many other lenses from other manufacturers that do the same thing at a significantly lower expense. What makes Leica lenses so different is their exceptionally high micro-contrast, i.e., an ability to register a nearly full variety of tonal variations between slightly darker and slightly brighter areas of very similar colors. It is the high micro contrast that is responsible for rich colors and smooth tonal transitions that all amount to the three-dimensional “feel”.

Importantly, micro-contrast has nothing to do with edge sharpness. That is why lenses with high micro-contrast do not have to be focused perfectly to get an image that looks acceptably sharp to the eye. That is also why a good portrait lens is forgiving to the skin structure by virtue of not being critically sharp, and at the same time renders a three-dimensional lifelike face with eyes  and lips that look alive. For instance, Summicron 90mm f/2 Pre-ASPH (it means, the last version before the current aspheric type) and Noctilux 50mm f/1 have this very property.

A magnitude of micro-contrast is inversely proportionate to the number of optical elements in the lens. The reason is that each optical element has two surfaces, and each surface is a source of internal reflections. Less reflections means more contrast, just that simple! That is why very complex optical systems (a.k.a zooms) almost never deliver high micro-contrast. Leica M lenses, on the other hand, are of relatively simple formulas. In fact, even compared to the best SLR primes, corresponding rangefinder lens formulas are simpler because they lack two extra elements that make the working distance longer. The working distance is the distance between a rear element and a sensor. It is mandatorily longer in SLR designs to be able to accommodate a mirror box. Leica M mirrorless design does not have this constraint, which makes it possible to create lenses that are smaller, lighter and on top of that, they seem to produce images of distinctly better quality.

It should be noted, however, that Leica and especially Carl Zeiss SLR optics, both primes and zooms, have high micro-contrast despite more complex lens formulas due to superior proprietary multilayer lens coating. Even though all modern lenses are multicoated, German lens manufacturers figured out how to do it better and keep it secret even from each other.

At this point I should correct myself, as a statement “a lens has high micro contrast” is not entirely correct. Leica lenses are capable of high micro-contrast , provided all possible sources of parasitic internal reflections should be eliminated. It means the following:

1. Always have a lens hood on: it will protect the front element from light rays falling at steep angles that are the most prone to reflecting.
2. It also means that filters should not be used indiscriminately. The filter introduces two additional surfaces into the optical system, and each of this surfaces can reflect on both sizes. Never wear a UV filter “for protection”, unless you actually do need protection: in the mountains and close to sources of UV radiation; on the water; when teasing a camel and documenting his reaction.

Even then you are not guaranteed to attain high micro-contrast. It is only under a certain type of lighting that things look stereoscopic: the best light is soft, contrasty and directional (note how much more of a 3D-look a ballerina on the image above has compared to the photo of a Barbie peddler).

Micro-contrast capabilities (or how some people call it “plasticity”) of a lens can be effectively revealed with soft and contrasty side lighting while reducing internal lens reflections to a minimum. Micro-contrast has nothing to do with measurable sharpness (which is the same thing as resolving power). In a sense, lenses with high micro-contrast mimic human visual perception: we see the whole image, not tiny elements of it. We think of an image as being realistic when it  has the color harmony and visual depth. This is, by the way, the reason why Leica never leads the world in the number of megapixels in its camera sensors. It simply does not need to: Leica images are perceived as more realistic not due to showing every single detail, but because it renders tonal gradations the same way the human eye does.

Leica Glow

One of the most misunderstood features of Leica lenses is the “glow”. Leica glow, which is a localized haze around highlights, is actually not something that Leica optical engineers were particularly proud of for a simple reason that it is nothing but residual spherical aberrations formerly unavoidable, especially in fast lenses and, to some degree, wide-angle optics. This glow gave older Leica lenses a special character, which, with some experience, could have been useful. What made Leica lenses different from other “glowing” optics like Canon 50mm f/0.95 is somehow Leica and some Zeiss lenses managed to maintain a decent level of micro-contrast while glowing. Optics from other manufacturers, while glowing, had very low contrast, sometimes to the point of making an image unusable.

Not all Leica lenses have the glow. Current ASPH lenses are so well-corrected that they show no aberrations of any kind. Older lenses of the Summilux Summicron (except 50mm f/2) series do exhibit this behavior. Combined with the good plasticity (a.k.a. micro-contrast), the glow can result in very beautiful images, and it is this combination of plasticity and glow that sets classic Leica lenses apart.

Usually the glow is the most pronounced wide open and completely subsides with stopping down to f/4. There are some exceptions, though. Among current lenses that still glow are, interestingly enough, Vario-Elmarit-SL 24-90mm f/2.8~4 and Vario-Elmar-T 18-56mm f/4.5~5.6. Older Leica-R zooms also show this tendency. Most recent (yet, not current) prime M lenses famous for this property are the following:

The classic example is Summilux 35mm f/1.4 Pre-ASPH: a tiny lens with remarkable characteristics. It showed virtually no distortions, was very sharp and had pretty high by those standards dynamic range. The glow can be very pronounced at f/1.4 to f/2, and it completely disappears when stopped down to f/2.8, and the contrast increases dramatically. Essentially, it is like having two lenses in one.

The glow is visible on the image above in two areas: more pronounced on a bend of the right hand and less so on the shoulder. The glow makes skin look smoother and creates a dream-like effect similar to the one of the Zeiss Softar I filter, but somewhat subtler. This lens was great for Leica M8, as due to 1.33x crop factor it had a field of view of a normal lens, and very thin anti-aliasing filter had no effect of its sharpness.

Glow of the Noctilux 50mm f/1 is different: it is less diffused around areas in focus and gets more similar to the one of Summilux 35mm f/1.4 in slightly defocused zones. With right lighting it makes the skin look like it is glowing from within.

Summilux 75mm f/1.4 has an unusual and beautiful feature: in addition to haze around highlights typical of other fast Leica lenses, it renders the glow around sharp edges between areas of moderate contrast. This effect is evident even at apertures as small as f/5.6 when highlights do not glow anymore.

Summicron 90mm f/2 Pre-ASPH is the most subtle, and it glows only wide-open. The glow is complemented by a beautiful bokeh and high micro-contrast. Arguably, this lens has the most iconic “Leica look” signature.

Viewfinder design

A somewhat obscure, yet very important factor contributing to the Leica look has nothing to do with lenses, but everything to do with a viewfinder design. Unlike the TTL view, the viewfinder of Leica M is always bright, regardless of the speed of a lens used. While this property can be seen as just a matter of convenience, combined with a coincidental rangefinder it makes manual focusing an effortless experience. Aside from constant viewfinder brightness, rangefinder design has several distinct features:

1. Firstly, it does not show DOF and perspective distortion of the lens used. It may seem inconvenient, but most rangefinder users do not see it as a disadvantage. Moreover, they maintain that not being distracted by optical effects of a particular optics they can concentrate on composition and importance of the content. As, an experienced shooter understands what effect wide or small aperture will have on DOF, or how the lens will affect perspective, he or she subconsciously puts more emphasis on the content and visual harmony.
2. The Leica M viewfinder has a constant field of view. Therefore, with lenses longer than 28mm, frame lines appear well within the viewfinder. This makes it possible to see things before they enter a frame, hence better anticipate their arrival. This is especially important in candid photography, where anticipation and serendipity are to major factors of success.
3. In most rangefinder cameras magnification factor is near 0.75x-1x, and it does not change when a different lens is attached.It allows keeping both eyes open, which makes the photographer more aware of the surroundings. No wonder that so many candid photographers convert to rangefinders even if they started out with much more popular and frequently more affordable SLR. Interestingly, even portraits and landscapes shot with rangefinders have a very characteristic and recognizable nuance of fugacity and spontaneity inherent to impressionism.
4. As the viewfinder is not coupled with the shutter mechanism, there is no blackout during the exposure. It enables a photographer see the scene at the moment of exposure. An SLR shooter, however, is effectively rendered blind when the shutter is open, and ends up not being able to visually control the very moment of taking a picture. That is why a Leica M photo is much less of a “lucky shot” than the photographer’s ability to take a picture at exactly the right moment.

Manual Focusing

It may sound like a heresy for some, but rangefinder manual focusing is faster than AF and , importantly, more reliable in low light. Focusing with an optical coincidental rangefinder, there is no guesswork whatsoever whether the object is in focus, or not, even when there is the only thing to see is a pair of catchlights in the eyes. When manually focusing through the lens with modern SLR that has a matte focusing screen, you spend time on figuring out whether you are in focus or not by defocusing slightly and then going back. It works reasonably well with fast lenses, but not as much with slower ones that make a viewfinder darker. With the rangefinder, it is always bright, regardless of the lens used, and there us no guesswork: if you see two images, it is out of focus, if only one, you are in business.

There is no such thing, however, as the “continuous manual focus”, at least not in still photography where there is no such luxury as a dedicated focus puller: a person standing beside a director of photography on a movie set. This is a constraint that requires a Leica M shooter to use a special approach to photographing moving objects. Instead of shooting a series of frames hoping that at least a few will be in focus and then choosing the best one, you need to  estimate an object trajectory, forecast its behavior across the trajectory, pre-focus the lens at where you expect the most interesting thing will happen and release the shutter when the object is there. As unbelievable as it sounds, this technique is not very hard to master, and, once mastered, it gives more reliable results than AF tracking, and the pictures come out less randomly looking.

Epilogue

So, to sum up everything discussed above, “The Leica look” does indeed exist. Even though there is no single magic ingredient that unequivocally makes Leica pictures look so special, it is a real phenomenon resulted from a combination various factors ranging from physical properties of glass to laws of optics to psychology of human visual perception. Leica images look different in part because of unique properties of lenses and because they are taken differently. The Leica look is a synthesis of vibrant colors, subtle inter-tonal transitions  and the visual story, which makes the image emotionally engaging in addition to its appeal of perceived visual realism. With an existing computer technology it is entirely possible to emulate the Leica look in post-production, yet, getting it in-camera takes no time, while the alternative requires serious Photoshop skills, sizable amounts of time and, in the first place, knowing what you are trying to emulate.

Irakly Shanidze © 2017