ReviewPosted March 2018

Zeiss ZM 50/1.5 C Sonnar


Everything is dim and subdued. Blue light shines from the tanks and the moving water makes it dance. Unmistakably fascinated she climbs up and gently touches that cool glass, separating our world from theirs.


There are plenty of reasons to like M-mount rangefinder cameras. Unobstructed viewfinders, compact size and high quality construction are traits that are shared by pretty much every M-mount camera.

But the biggest appeal might lie beyond the cameras themselves – the system also offers a wealth of prime lenses, a diversity unmatched by most other systems. Everything from uncoated, super-simple designs from the early days of photography, to highly corrected contemporary lenses are readily available and compatible with whichever M-mount camera camera you prefer to use.

Even in such diverse company the Zeiss ZM 50 Sonnar stands out as something unusual. Pretty much a straight reissue of a 1930’s design the ZM Sonnar also makes use of modern coatings and materials, giving the lens some unusual characteristics. The biggest oddity isn’t the age of the design, but instead that it’s not as balanced as most contemporary offerings, trading clear strengths against some equally apparent drawbacks.

It’s not a lens that’s quite as easy a recommendation as something more well behaved, but in many ways it’s more interesting. And for anyone enjoying its strengths, it’s also unique enough to be preferable to almost anything else.


The Sonnar is a fast, slightly long, normal that’s exceptionally compact for its specifications.

The Sonnar formula was originally developed to get around some of the challenges faced in lens design before the invention of lens coatings – flare in particular. The design uses six spherical elements with three of them in a cemented rear group. This leaves few air to glass surfaces, increasing transmission and reducing flare. In this modern iteration all surfaces are also multi coated using Zeiss’s highly regarded T* process leading to even better flare resistance.

There are no versions to keep track of – it’s remained unchanged since its launch in 2006 although some focus calibration tweaks and material changes have been made over the years, so a more recently made lens can be somewhat more desirable. The lens is produced by optical manufacturer Cosina in Japan, also the parent company of Voigtländer.

As all M-mount lenses it’s manual focus only. Unusually for a modern lens the Sonnar only focuses down to 0.9m, rather than the more common 0.7m.

Lens-mount Leica M bayonet
Length 38 mm
Weight 240g
Diaphragm 10 blades, f/1.5-f/16, third stops
Elements / groups 6 / 4
MFD 0.9m
Filter thread 46mm



A rain falls heavily against the leaves. As usual the island is emptying out after the weekend. Turning the corner we see our neighbours drive away to the main road, towards the ferry. We put the last bag in the car and head back to the city.


Appearance & construction

Even at a first glance the Sonnar stands out, at least when you consider its specifications. It’s exceptionally compact and smaller than many slower lenses of the same focal length. Its shorter but wider dimensions make it look a little stout next to its ZM siblings.

Size aside, the Sonnar is a nice looking lens with a refined exterior design. Not quite as understated and utilitarian as most of Leica’s lenses, it instead strives to look a bit more elegant, a matter of taste which approach is more appealing.

The entire ZM line is close to identical in appearance except for barrel length and sometimes diameter. As I’ve owned four different ZM lenses and shot a few more still I feel I can comment a bit more generally about the construction, finishes and quality than what I’d be able to do based on just the single lens that this review is centered on.

Materials & mechanics

The ZM lenses are manufactured to a very high standard, being made almost exclusively from metal and glass, with very good durability and feel. There are some minor quality issues to look out for however – something I’ll get back to in a bit.

The housing is made from aluminium. Most ZM lenses are available in both black and chrome finishes.

The black finish has changed a bit over the years with earlier lenses being lacquered and somewhat shiny and later ones anodized and more matte. The ZM Sonnar I’m reviewing here is a bit more matte compared to the 50 Planar and 35 Biogon I’ve reviewed previously. I prefer the more matte finish both from an aesthetic and functional perspective – the earlier, shinier lenses attract more fingerprints and grime and don’t feel quite as pleasant.

The chrome finish is matte and feels quite refined. Unlike the black lenses the process doesn’t seem to have changed much through the years.

Either finish is very durable, perhaps even more so than the Leica and Voigtländer counterparts with all my ZM lenses having only shown minimal marks of wear.

Front and rear of the ZM Sonnar. Samples from the Leica M4-P.

Most Zeiss ZM lenses are manufactured by Cosina in the same plant as Voigtländer lenses and a few similarities in build can be seen. For instance the front ring is identical to some of the Voigtländer M-mount lenses and some accessories can even be used interchangeably between them. The ring is made from chromed brass, a hard wearing material but also highly visible and can cause visible reflections when shooting through glass.

The aperture generously has ten blades resulting in highlight stars with ten points and potentially contributing to smoother bokeh stopped down.

An unusual characteristic of the aperture is that it doesn’t stay circular throughout the range, instead being somewhat star-shaped at mid range aperture settings. This is by design and serves to mitigate focus shift – one of the less desirable traits of a pure Sonnar design and a topic I’ll get back to in the Image quality section.


The lens at f/4, f/2 and f/8 respectively. Note the unusually shaped aperture at f/4.


Markings are engraved and painted in two variations of DIN (with a few bespoke characters). On a black lens the metric distance scale, aperture and depth of field scales are painted white and clearly visible in any light. The imperial scale, focal length identifier and IR index marker are painted red, in a shade that’s reasonably easy to read in most conditions*. On the chrome lenses the metric scale is in black and the imperial one blue.

* interestingly the shade seem to have shifted over the years with my older 35 Biogon and 50 Planar having a much more subdued red color that’s harder to read in low light.

Full aperture stops are marked with numbers. Unlike Leica and Voigtländer lenses the intermediate stops also have markings. As the ZM lenses have third stop settings on the aperture instead of the usual half stops the markings are motivated.

There are clear markings on the lens for focus range, depth of field and third stop aperture settings. Sample from the Leica M9.


There’s no hood included, but a vented metal one is available. It’s priced dearly and while it’s well made I don’t feel it’s worth getting as the lens is very flare resistant.

The front lens cap might seem pretty irrelevant to touch on, but the ones for the ZM lenses are by far the worst ones I’ve ever come across. It’s frankly pretty incredible how poor the cap is considering it’s a problem that’s been solved for decades by every other lens manufacturer. Somehow the ZM lens caps manage to be both fiddly to put on and incredibly loose once fitted. Because of this I prefer to use third party caps for my ZM lenses.

The lens cap for the ZM line of lenses are surprisingly awful.

Feel & durability

As for mechanical feel the aperture settings are very refined. Each stop has just the right amount of distinct resistance and feels reassuringly solid.

The focusing feel is great on my copy of the ZM Sonnar, smooth and with a low, well balanced resistance.

However the focus mechanics is a potential weak spot with the ZM line. While the majority of copies work well, some lenses develop signs of wear very quickly (in a matter of a few years, compared to decades for most other manual focus lenses). Binding and inconsistent focusing feel are the most common issues. Some ZM’s also develop a wobble where the optical cell becomes loose in relation to the focusing helicoid*.

* I’ve encountered all these issues myself, so it’s not a matter of hearsay. The worst problems was with a ZM 28, an optically magnificent lens that I shot over a few years. During that time the focusing feel went from pretty good to quite awful with binding and a pronounced wobble. Servicing brought it back to feeling fine though.

Lenses from more recent production batches seem to anecdotaly exhibit less issues than earlier ones* and copies that exhibit these problems seem to be in a clear minority. In my experience any problems are also remedied by a normal servicing.

* My guess is that these issues are probably due to the chosen lubrication or materials, or a combination of both. So it makes sense that adjustments to the production would reduce the problems.

Problems like these aren’t unique to the ZM line but what’s unusual is how quickly they develop in some of the lenses. While it’s no surprise that the cheaper Zeiss lenses aren’t quite on the same level of construction as Leica’s equivalents it’s notable that the Voigtländer lenses I’ve shot have been more consistent in feel, especially considering that they are made in the same factory and generally sell for less.

Now, that this potential issue exists isn’t really something that has dissuaded me from the ZM lenses. As more recent lenses seem unaffected and all the ones I currently own feel really good, even after years of use, I don’t worry much. Considering even a lens with severe issues (like my ZM 28) can be brought into good condition by a simple servicing these problems definitely don’t make me choose other marquees over Zeiss.

Still I do factor in that a ZM lens might need more frequent servicing when I buy them. So if they later do need it, I’m already prepared and if they don’t I’m pleasantly surprised.



We stroll aimlessly, waiting for our friends to meet us for dinner. On instinct we head down a narrow street and suddenly find ourself on pitch black sand and rocks, greeted by the sun setting behind the mountain peaks of the neighboring island.



The entire ZM line share practically identical ergonomics. The lenses are definitely sound in this department, the Sonnar included. There are no major issues, but depending on your preferences it might fall short of being best in class.

Focusing nub

A point of contention between rangefinder photographers is whether focusing is best done with a tab or a ring. Traditionally rangefinder lenses in the wide to normal range have been equipped with a lever or tab and longer lenses a ring. The tab offers more haptic feedback and with experience you can start to tell and set the focusing distance by feel. Some people prefer the ring despite losing that additional positioning information since it can be grabbed anywhere around the circumference of the lens and act the same way. A ring can also have a longer throw which makes it a better fit for longer lenses. Each solution has firm followers and to some a lens featuring the “wrong” alternative can mean that it won’t even be considered for purchase. With the ZM line Zeiss has aimed to come up with a solution that pleases both groups.

The focus ring is a finely ribbed, reasonably wide band around the entire lens circumference offering good grip regardless of conditions. At the position where the tab is generally placed is a small protrusion of the ring – this little nub aims to bridge the gap between a focusing tab and pure ring. It means handles like a normal ring, but that it’s also possible to set the focusing distance by feeling the position of the nub.

The focus nub is pleasant in use.

To me it’s a pretty good compromise. I’m firmly in preference of tabbed lenses, but in practice the ZM nub is a clear improvement over a plain ring. While not as quick or comfortable as a tab, the nub still makes it possible to set focus distance by feel.

The Sonnar is a little less straight forward in this regard though. As the starting point is 0.9m instead of the standard 0.7m close focus distance and the travel is similar to most other lenses the position of the nub is a little different throughout the focus range from where it would be on lenses with the more common minimum focus distance. This is only an issue if you switch frequently between lenses with tabs though and even then I’ve found it easy to adapt*.

* this little quirk has only really been particularly noticeable in my use when I’ve shot the Sonnar together with the Voigtländer 25 Skopar, a lens that has the same issue only in the opposite direction as it has a MFD of 0.5m. Switching between the two lenses definitely threw my muscle memory off for a few shots.

Another particularity of the Sonnar is that the focus throw is somewhat short, at least considering the focal length and speed of the lens. At just about 90° it can be a little more challenging to nail focus wide open than with a wider throw, especially since one of the rendering characteristics is a well defined plane of focus. On the other hand this makes the lens feel quick to focus and fast to work with so I’m not sure I’d want to have it differently.

An issue that can plague small lenses with focusing rings rather than tabs is that it becomes hard to separate the aperture and focusing rings by feel (the Summicron 50 V is a relevant example of this – since both rings are practically identical as well as placed close together I sometimes grab the wrong one). The ZM lenses do well here. While pretty close together the two rings have slightly different texture and shape making it easy to tell them apart.

The ZM Sonnar is quite compact for what it is.

Third stop aperture settings

Unlike most M-mount lenses the aperture is set in third stop increments instead of half stops. As I rarely even use half stops, third stops feel overkill for anything I shoot.

The only result is that the lens feel a bit slower to work with in this regard. However some people might enjoy the added control this offers.


As mentioned the Sonnar is small for its specifications. This makes for a very pleasant kit in use as there also aren’t any real ergonomic drawbacks to the small size. The lens feels well balanced on most cameras and it doesn’t intrude by any noticeable amount into the viewfinder on any of the rangefinders I’ve shot it on.

That it’s quite fast despite this being as small as it is makes it an interesting choice, especially combined with a few additional and appealing traits in the next section.



It wasn’t a great year for our trees. A cold and cloudy summer left us with no more than a handful of sort of ripe cherries and three sour apples. At least the plums were delicious.


Image quality

Assessing the performance of a lens can be tricky. Many different factors come into play, but the impact of them can differ significantly depending on how a lens is used.

Beyond that it’s also impossible to evaluate anything in isolation, but every comparison depends on your frame of reference. Pit any lens against the absolute benchmarks in the industry and there can be a lot to complain about even with very reasonable performers.

There are also a number of characteristics that are hard to quantify but have a bigger impact on how the actual output is perceived than easy to measure metrics such as lines resolved per millimeter or distortion.

The ZM Sonnar is affected by all these factors and it’s not surprising that it’s a lens with a mixed reputation in regards to its performance.

With things easily measured it’s somewhat unspectacular compared to contemporary benchmark lenses. It also suffers pronounced focus shift that makes its output something of a moving target.

Combine these traits and we end up with a lens that’s often simply described as a “character” lens to the point of it sounding like its almost unusable in general use.

Still in practice the performance is well ahead of adequate. Add to that some incredibly appealing traits that are hard to quantify in objective testing but very apparent in the resulting images and the Sonnar begins to feel like a bit of a bear to break down.

For those only interested in the broad strokes let me offer the briefest of summaries – in use the Sonnar has stunning output with one of the most appealing balance of characteristics I’ve come across. And despite falling short of being impressive at close scrutiny I’m frequently exceedingly happy with the overall output.

Still there are some interesting characteristics that also have practical implications, so a full breakdown still feels relevant. So let’s dive in to the nitty-gritty – down the rabbit hole we go.

While there are some shortcomings and caveats I still feel the ZM Sonnar has an incredibly appealing signature that shines through almost regardless of subject.

Resolution & contrast

The Sonnar has gentler contrast characteristics overall compered to its most well corrected peers.

At higher frequencies contrast is moderate and pronounced spherical aberration can be observed, giving a less distinct rendition of smaller detail and less resolution than benchmark lenses. This is especially true at farther distances.

The behavior is reproduced predictably across the frame with peak performance on axis and a gradual loss of definition towards the edges and corners, which are comparatively poor.

On the other hand global contrast is exceptionally high, already at wider apertures. This gives an overall impression of clarity and presence that can be lacking even in lenses that has stronger definition at higher frequencies.

The combination of subdued definition of fine detail and high contrast at lower frequencies gives images a rounded sharpness that might not look impressive at close scrutiny but still gives high apparent definition when examined at more reasonable magnifications.

These traits are evident already wide open and stays remarkably consistent even stopped down. This is positive in the way that the performance at wider aperture is already adequate but on the other hand you don’t really gain as much stopping down as you usually do. Still contrast is improved across the board and detail is more clearly defined as you reach smaller aperture settings, but in terms of pure resolution it never gets to quite the same impressive levels as can be seen elsewhere.


Pure resolving power isn’t really where the ZM Sonnar shines. This example demonstrates the lens at its weakest. As you can probably tell by the crops – detail can come across as subdued and lacking bite at wider apertures and farther distances in particular. Still stopping down brings the definition to very acceptable, if not necessarily impressive, overall levels.
– Leica M9



At close to medium distances the ZM Sonnar isn’t really too compromised though. Sure, the best lenses in its class offer slightly higher resolution that holds up better towards the frame periphery, but the ZM Sonnar can certainly hold its own under these circumstances and offers quite respectable definition in the central parts of the frame.
– Leica M9


So while parts of this might suggest that the ZM Sonnar is a poor performer, it’s only within the context of comparing to truly excellent lenses the Sonnar really falls behind. And even then it’s mostly with regards to the reproduction of finer details at farther distances. We’re splitting hairs here but for general use you’d be hard pressed to fault it. When it’s at its weakest it’s an average performer. However the high contrast at lower frequencies still leaves the overall output unusually satisfying when not simply scrutinizing the details.


The colour reproduction is a clear strength of the entire ZM line and the Sonnar is no exception. The palette is warm and clearly saturated. There’s a subtlety and distinction between close tones and the overall palette is exceptionally appealing. The lens is a definite benchmark in this regard.

Bokeh & transitions

The Sonnar has very appealing bokeh in general. The lower amount of correction of spherical aberration within the focal plane leaves out of focus highlights quite gentle and pleasant looking.

That’s not to say that it’s totally bulletproof however. Wide open there can be strong edges to bokeh balls and in challenging light out of focus areas can certainly come across as somewhat messy. Most of the time it does very well though.

Stopping down improves bokeh and reduces the likelihood of a messy impression. It really shines between f/2 and f/2.8 with pronounced separation, increased contrast and smooth bokeh. The star-shaped aperture between f/2.8 and f/5.6 can at times be visible as mirrored in the shape of the bokeh balls, though as it’s not generally apparent if you’re not looking for it specifically it ends up more of a curiousity.

So despite occasional issues the Sonnar is a better performer than most peers with regards to out of focus rendering.

A trait of the Sonnar is rapid transitions between planes of focus, with very pleasing transitions zones to boot. In focus subjects look unusually well separated against out of focus areas and the bokeh appears pronounced. This is obviously most apparent at wider apertures but even stopped down there’s surprisingly distinct and separated planes and with the increased definition in the focal plane this can lead to a very pleasant look at mid range apertures, even at a distance. To my eye these swift transitions contribute almost as much as the balanced bokeh to the overall look of the Sonnar in terms of depth of field.

The one wrinkle to this characteristic is that it means more careful focusing is required compared to a lens with gentler transitions. This can be especially tricky with one of the least desirable traits the Sonnar has to offer…


The ZM Sonnar offers better bokeh than many peers. In challenging situations strong edges and nervousness can be seen in out of focus highlights, especially wide open, as demonstrated in the example with the raspberry plant. But as can be observed in the other samples the ZM Sonnar tends to perform well, even in situations where other lenses often look messy, particularly if it’s shot stopped down slightly.

Focus shift

Focus shift is when the point of focus moves backwards and forwards depending on the aperture setting despite not moving the focus ring.

With most lenses there’s not a lot to say on focus shift. A sentence or two at most. Definitely not enough to warrant a separate section. But with the Sonnar this topic is a bit of a sticking point. Focus shift is an effect of under corrected spherical aberration, a characteristic I’ve already brought up and that influences bokeh positively but resolution and focus accuracy negatively.

Stopping the lens down gradually moves the focus backwards as the spherical aberration affects the focal plane to a lesser extent. The closer the distance the more noticeable the shift. While this isn’t unusual in its own right it’s the amount of shift that really starts to raise some eyebrows. Under controlled conditions the point of focus can be observed to move several centimeters backwards as you stop down.

This isn’t really an issue shooting with live view, but as a rangefinder can only be calibrated to provide accurate focus at one specific aperture setting this can obviously make it tricky to really nail focus at intermediate aperture settings. Even if you focus accurately the focal plane can be off simply because of the aperture you’ve selected.

So attaining adequate focus accuracy at as many aperture settings as possible instead becomes an exercise in compromise. Calibrating the Sonnar for accurate focus wide open will result in significant back focus at f/2-f/4. By f/5.6 and beyond depth of field covers the shift more or less completely, regardless of calibration. If one instead elects to calibrate for accurate focus slightly stopped down, at say f/2.8, you will get significant front focus at f/1.5-f/2 and very slight back focus at f/4.

Obviously doing your own recalibration of a lens not designed to be end user adjustable is not a straightforward procedure. And unless you know what you’re doing it’s probably best to leave it lest you do more harm than good.

Fortunately the default calibration represents a very reasonable tradeoff. When the Sonnar leaves the factory it’s calibrated to focus correctly at f/2*. The result is slight front focus at f/1.5 and slight back focus between f/2.8 and f/4**.

* Though reportedly this has changed somewhat through the years with older lenses being calibrated to f/2.8 – something that seems a much less preferable tradeoff.

** This obviously hinges on both your lens and rangefinder camera being in spec and consistent with each other. Something not guaranteed, though still a good deal more likely than what rangefinder detractors claim.

To illustrate the focus shift I made two exposures without changing anything but aperture (though handheld so the framing differs very slightly). The rangefinder is focused at the 50 cm mark of the folding rule, but as you can see below the focus is slightly off at both apertures demonstrated here. At f/2 the focus is spot on.


f/1.5 – Best focus is ahead of the focus point.

f/2.8 – Best focus is behind the focus point.

This calibration makes a lot of sense. Even without taking focus shift into account at all the accuracy is generally quite acceptable throughout the aperture range for general use. The shift is most visible at f/2.8 and f/4 but with many types of images it’s often not a problem. What you've focused on generally stays acceptably sharp both wide open and at f/2.8-f/4 as hopefully demonstrated in the crops above.

And if you’re somewhat aware of the behavior and shoot the lens sensibly the focus shift becomes a complete nonissue in practice.

So to expand a bit on what I mean by these last few statements I’ll give a bit of practical advice on how to get the most out of the Sonnar without jumping through all too many hoops.

Now just to reiterate that neither point is at all necessary to get pleasant results. I don’t really live as I learn in this instance. I’ve made a bunch of keepers both wide open as well as between f/2.8 and f/4. Sure if I scrutinise the images I can sometimes see the focus being very slightly off, but rarely, if ever, have I taken issue with the full frame because of the shift.

This is probably explained, at least in part, by the fact that the focus shift is uneven across the frame. It’s less pronounced in the mid-field compared to the center. So if you compose according to the rule of thirds, for instance, the focus shift will be even less problematic.

Then there are obviously also situations where focus accuracy isn’t quite as critical and then these points can also be completely disregarded.

Still in terms of very simple advice then sticking either to f/2 or shooting well stopped down makes sense from the perspective of minimizing any troubles from focus shift.

Just one example of a frame shot wide open. As the day was nearing an end the light coming from the nearby windows were actually quite dim and it would’ve been hard to get as nice an image at f/2. I don’t really worry about focus shift in situations like this, or many situations at all really.


Beyond the focus shift there’s mostly good news in terms of additional aberrations.

Vignetting is modest with around a stop wide open, reduced to less than a stop by f/4 and insignificant amounts by f/8.

There’s no distortion to speak of. There’s a fraction of a percent measurable in exacting tests, but that little distortion is not really visible under practical circumstances.

The Sonnar is also exceptionally resistant to flare, one of the original strengths inherent in the design and the use of Zeiss’s excellent coatings improves things even further. It’s not totally immune to ghosting but it really is close. I’ve seen some occasional traces of it, but rarely anything even close to what most other lenses end up with in challenging situations. Contrast and definition remain high even in tough light. Occasionally a veiling flare can be seen in areas surrounding bright light in high contrast scenes – a trait that actually ends up quite appealing. Under very specific conditions a very large portion of the frame can be afflicted by veiling flare, but this is something I’ve only seen in once or twice over thousands of frames. Overall it’s a very impressive performance, definitely among the best in its class.

Color fringing can be observed around high contrast detail such as tree branches. It’s not unusually prominent though, and generally easy to correct.

Coma is reasonably well controlled, though not perfect. Highlights distort slightly towards the edge of the frame at wider apertures which makes the lens less than ideal for e.g. astronomy use. Beyond that specific use case though it’s not visible or distracting in common use.

The lens also does well in terms of field flatness with a subtle curvature towards the camera visible at closer distances.

Occasional veiling flare in extremely high contrast areas is usually as bad as it gets in terms of flare. To my eye this characteristic generally looks far more appealing than how many other lenses handle situations like these.

Differences between mediums

The evaluation above is valid regardless of capture medium, but nuances exist and since digital is more revealing in many cases that’s the primary medium for analysis. The rendering of course carries over regardless of medium but the subtleties can be perceived slightly different.


The slightly gentle character of the Sonnar works really good on digital in my opinion. It takes away a bit of the hyper realistic bite that can make digital look almost too good at times, while still retaining a lot of definition. The color response seems well suited to digital capture and the resulting files feel very dense in terms of color detail. Some aberrations such as the focus shift and color fringes are more visible on digital than on film but when examining the files at moderate magnifications the overall impression is still exceptionally appealing.

Colour film

I’ve shot the ZM Sonnar on color film more than anything else. The strong color palette and high global contrast often makes for incredibly appealing negatives. That film is a bit more forgiving to for instance focus shift and color fringing means that there’s very little to take real issue with. Every positive trait also carries over with very pleasant looking output.

Black & White film

The Sonnar does really good for B&W to my tastes*. The rounded sharpness lets the output avoid looking harsh and the high overall contrast still leaves quite a bit of punch to the negatives.

* I feel it’s especially well matched to classic, cubic grained, emulsions which play well to the lenses strengths. Though this also depends a lot on the situation and context. I’ve been shooting mostly T-Max for B&W lately and the Sonnar really shines here too.

The ZM Sonnar does well regardless of medium. Here’s one frame from the digital Leica M9 and one made on Ilford HP5 Plus using the Leica M4-P.

Overall rendering

If there’s a reoccurring theme throughout this section it is that the performance of the Sonnar varies significantly depending on what magnification you examine it at.

Look closely and you’ll discover some clear and objective shortcomings. The resolution isn’t quite up to par with the best lenses in its class. And pronounced focus shift makes the output unpredictable and can further rob the output of fine detail at certain aperture settings.

Pull back your nose from the screen a little however, and start taking in the entire image, and you’re treated with pronounced strengths. The high contrast at lower frequencies gives an overall impression of high clarity and presence to subjects depicted. Balanced bokeh and rapid transitions lets you play with distinct focus points and adds a marked depth to the images. Low distortion, high resistance to flare and refined color palette is more or less icing on the already very tasty cake.

Based on this unusual dicthonomy many opine that the ZM Sonnar is a “character” lens, perhaps appealing for portraits but falling short for everything else. And while I can see where these opinions are coming from I simply don’t agree with the assessment. Sure the lens has traits that makes for appealing photos of people but these same traits also translate well for most any other type of photos I like to shoot. And at times its rendering comes across even more strongly in situations outside of the typical portrait settings. And beyond the appealing signature it’s certainly well behaved enough to make for a fine general use lens.

Most reservations towards the Sonnar seem to hinge on the focus shift. Something I worried about initially but to me proved a nonissue in use. Sure there are some workarounds to minimize any issues and I’ve occasionally picked a different aperture setting than I would’ve with another lens. But even in this regard I haven’t been very consistent with my approach. I’ve pretty much shot anything and everything I’ve felt like without worry. And I’ve rarely been able to make out significant effects of the focus shift, much less taken issue with them.

So then the only shortcoming I feel has a bit of bearing in practice is the slight lack of bite at longer distances, even when stopped down. Something that can make certain types of images look a little dull. On the other hand the gentler signature capture the mood and a sense of place even better than something sharper under some conditions. So while we’re mostly splitting hairs here, it’s a trait I’m not overly fond of, though one that I still don’t have any problem accepting and occasionally even enjoying.

As for a wrap up; on a purely academic level the ZM Sonnar falls a little short of being impressive, despite having quite a few impressive traits.

Subjectively though, it has a uniquely appealing signature and I’m quite smitten with it. To put it plainly, its output just looks exceptionally nice. It makes simple things look beautiful and beautiful things incredible. I’ve shot quite a few lenses objectively more impressive than this but few that have given me images I’m so happy with from an aesthetic perspective as frequently as the ZM Sonnar.

So in the end any minor flaws it has simply falls away and all I’m left with is image after image that really appeals to me.



As I’m heading home in the setting autumn sun Ivar brings food to his sheep. I enjoy having a chat whenever our paths cross. He’s lived here off and on since birth and is on a first name basis with every permanent resident on the island. He shares stories of past and present and before I know it half an hour has passed.


Specifics in use

I’ve had the ZM Sonnar for about two years as I write this and I’ve put it through its paces for sure. After the Summicron 35 ASPH the Sonnar is my second most used lens in the past few years. I’ve used the ZM Sonnar under almost any conditions imaginable and wide ranging situations so I feel I’ve got a good handle on how it behaves.

I’ve been a little torn to the 50mm focal length in the past, feeling it too be a little tight for a normal and a little short to feel like a proper tele. Still in the past few years I’ve come around to the focal length and now feel right at home, enjoying the slightly narrower frame and added compression compared to something like a 35. I especially enjoy the focal length as part of a two lens kit, paired with something wider. And shooting the ZM Sonnar together with the 28 Summicron has been one of my favourite outfits of recent memory. I could probably shoot that combination indefinitely if it wasn’t for my own restlessness.

Since coming around to the focal length I’ve been skipping around a little bit between a few different lenses, letting me get a better feel for some of the varying traits on offer. And while I’ve certainly been very happy with the alternatives I’ve been shooting, the ZM Sonnar simply feels like a better fit for me most of the time.

The beautiful and distinct rendering I’ve written about at length is the main reason for this. But a few additional aspects also contribute to my preference of the ZM Sonnar.

That it offers an pretty much a full stop of additional light gathering compered to an f/2 lens without any size penalty is really appealing for instance. With a 50/2 I run into situations where I find it a little limiting a bit more often than I’d like. Sure I can still get away with an f/2 most of the time but the f/1.5 Sonnar gives me a bit more leeway in marginal conditions. It allows me to shoot in pretty much any light I feel like even with film or on the M9 with its modest high ISO performance.

Good ergonomics and handling isn’t factors that necessarily sets it apart from the closer alternatives, but is obviously nice to have.

0.9m close focus

One of few traits I don’t like with the ZM Sonnar is the 0.9m close focus distance. This is long for a contemporary M-mount lens where 0.7m is commonplace.

While it’s not a huge hindrance most of the time, I do run into this limitation often enough that I find it a bit annoying. For shooting details and in closer quarters it’s an unfortunate restriction. Especially since many even smaller lenses don’t share this limitation.

For my personal tastes it might actually be my biggest reservation towards the ZM Sonnar compared to other options. Still, as it has so many other positives this is rather easy to look past.

Leica M4-P

Excellent. The appealing rendering and high speed of the lens makes it a very pleasant matching to a film camera and the combination stays usable in even exceptionally low light. The small size lets the lens balance and handle exceptionally well. The compact dimensions also means that it doesn’t intrude into the viewfinder by any meaningful amount – there’s minimal overlap even at closest focus distance.

Leica M9

Excellent. Balances and handles great. The rendering is beautiful and the color signature feels like a really good match to the sensor in the M9. Picking the lens profile for the Summilux 50 pre ASPH (11868…) gives pretty good correction of color shift and vignetting, though not quite perfect. With large areas of neutral color in the image some slight residual color shifts can be seen. It’s not generally noticeable but if very exacting results are required then correcting in post processing with custom profile could be a better approach. The lens doesn’t intrude into the viewfinder by any meaningful amount – there’s minimal overlap even at closest focus distance.

Leica M Typ 262 (240)

Fantastic. Wonderful handling and beautiful rendering. No viewfinder blockage to speak off. The solid high ISO performance combined with lens’s fast aperture means it’s possible to shoot even in exceptionally low light.

Sony A7

Excellent. The ZM Sonnar is actually one of my favourite lenses to shoot on the A7, and even one of the reasons I still have the camera. I wrote a short note on this a while back and won’t reiterate too much, but the lens and camera play to each others strengths really well. The handling is very pleasant and the rendering carries over very well with only minute ray angle induced issues. There’s a little bit of smearing towards the edges at wider aperture and farther distances, though already by f/2.8 the full frame looks just about acceptable even at infinity. Stopping down further makes for even less issues. There’s no color shift to speak of. Focus shift is a total nonissue as you focus through the lens and you can focus with absolute accuracy regardless of aperture. The color palette goes together beautifully with the color response of the Sony sensor. The high speed of the lens and good high ISO performance of the camera also lets you use the combination in really, really low light. The A7 is slower to shoot as you need to zoom in to focus accurately and it’s harder to time shots with the long viewfinder blackout and slight shutter lag which is why I still prefer to use the ZM Sonnar on a rangefinder, but other than that I’ve really been enjoying this combination.



Walking up the road to the house they pick whichever flowers have popped up since last we were here. The bouquet signal the coming summer as surely as the migrating birds that call above.


Alternatives to consider

As 50mm lenses is such a popular choice for rangefinder cameras there’s almost an infinite amount of options in terms of what lens to get. Cheap, fast, slow, expensive, exotic, old, compact, tab focus, close focus, LTM mount, you name it – it’s available. It’s almost impossible to cover all the alternatives, so I won’t even try. Instead I’ll break down some of the most important differences to the lenses I’ve been shooting recently as well as some of the more relevant and close alternatives available.

Leica Summicron 50/2 V

Between the Summicron and the Sonnar the choice seems pretty straightforward. Despite being a stop faster the Sonnar is the same weight and even slightly smaller than the Summicron, as well as significantly cheaper. End of story, right? Well not quite – while I hold the Sonnar as the 50 with the most pleasant rendering the Summicron is a very close second, and as it has a few other positive traits it could make for a more compelling option for some people. Beyond the beautiful signature the output is also more well corrected and it’s a higher performing lens in terms of resolution and micro-contrast. It’s better made, focuses down to 0.7m, doesn’t suffer from focus shift and has a very clever integrated hood. It’s more prone to flare though and the ergonomics is a little worse. To me it’s close enough to be a wash overall, but the slightly prettier rendering from the ZM Sonnar combined with the fact that it’s a bit faster makes me prefer the Zeiss to the Leica by a nose.

Read the full review


Zeiss ZM 50/2 Planar

The Planar is a great lens in pretty much every way. It’s similar to the Summicron in that as it’s a double-gauss design it’s more well behaved than the ZM Sonnar. It has higher contrast and resolution at higher frequencies, no focus shift and great resistance to flare. It really is an impressive performer by any standards, and considering the much lower price than either the Sonnar or Summicron it’s an easy lens to recommend. It also focuses down to 0.7m, has solid ergonomics and is noticeably lighter. Had I never shot the Summicron or Sonnar I would’ve held the Planar among my favourite ever. But comparing the sets of images I’ve made with the Planar to the ones from the Sonnar and Summicron I simply gravitate more towards the output from the other two lenses. The Planar has a very efficient signature, but both the Summicron and the Sonnar in particular renders beautifully. Now the differences mostly comes down to splitting hairs, and there’s not a bad lens between them. And for a lot of people it might make more sense to go with the Planar, but for me it has simply ended up the 50 that I enjoyed the least of the ones I’ve been shooting concurrently.

Read the full review


Three fantastic 50mm lenses I’ve been shooting concurrently.

Voigtländer 50/2.5 Color Skopar

A fairly recent favorite of mine that I find a great day to day choice. It’s a lot more limited in terms of speed compared to the ZM Sonnar, but it’s tiny, quite well behaved, focuses down to 0.75m and can be used on thread-mount cameras. The ZM Sonnar has a slightly more appealing signature though, and the faster speed is quite compelling.

Read the full review


Voigtländer 50/1.2 Nokton

A lens I’ve been shooting a lot recently and enjoyed immensely. It’s more competent and well behaved than the ZM Sonnar, but still with an incredibly appealing rendering. It’s faster, priced similarly and focuses down to 0.7m. The tradeoff is that it’s noticably larger than the ZM Sonnar. A review is coming.

Leica Summicron-C 40/2

The Leica Summicron-C 40/2 is a little bit wider, but still feels like it’s in the same ballpark. It’s a very pleasant performer and a bit of a bargain at the going rate. The character is a bit more neutral than the Sonnar, without becoming clinical. You loose a bit of light gathering but the Summicron-C is a lot more compact – one of the smallest Leica lenses ever. And despite the smaller size the ergonomics is equally good as with the Sonnar. Resolution is a bit better on the Leica, especially stopped down, but overall contrast lower. It’s also far more prone to flare and has much more nervous bokeh. Most rangefinders lack corresponding framelines, but that’s a minimal issue in practice. Overall I really like both lenses but for slightly different reasons.

Read the full review


Voigtländer 40/1.4 Nokton

The Sonnar and Nokton share a few traits that I feel makes it relevant to comment on in this context. Both are close to normal focal length lenses that are unusually small for their specifications. Both are fast and handle really well. Each also has a few traits that can make it seem temperamental before getting to know the lens. The Nokton is based on the double gauss design that’s traditionally more balanced, which affords it both negative and positive traits over the Sonnar. The performance is pretty much on par though the Nokton does have a bit more bite stopped down and less focus shift. The design is more under stress at wider apertures in this implementation however and there’s noticeable unevenness across the frame and the bokeh is generally a lot more nervous. The color palette is also slightly less refined than with the Zeiss lens. So the output from the Sonnar tends to look more appealing overall, especially at wider apertures. Most rangefinders lack 40mm framelines, but that’s not a huge issue in practice. Ergonomics is a bit better with the Nokton, it focuses closer and it’s smaller, lighter and cheaper too. So the overall decision isn’t easy. I’ve stated that the Nokton is among my favourite lenses on several occasions, but I might actually have to concede that I’ve come to prefer the Sonnar.

Read the full review


Other alternatives

So as I stated initially there’s plenty of choice in 50mm lenses. So I won’t go into much further detail than I’ve already done, except I want to very briefly touch on a few options I’ve not yet shot.

Leica Summilux 50

Both the earlier Leica Summilux 50 versions and more recent ASPH release look like great lenses and perhaps the most obvious points of comparisons to the Sonnar simply based on speed. However either version is quite a bit heavier and more expensive than the Sonnar. The performance of the earlier version looks to be pretty similar to the Sonnar and has a quite appealing signature to my eye, though out of focus areas look very nervous in many samples. The more recent ASPH version is more well corrected and has really impressive output, including appealing bokeh, though the price and weight difference is even more significant. I’ve not had a chance to shoot with either so far.

Voigtländer 50/1.5 II

The recent Voigtländer 50/1.5 has been brought it market since my initial review of the ZM Sonnar. It looks like a swell lens with an appealing signature (though not quite as appealing as the ZM Sonnar to my eye). It seems better behaved than the ZM Sonnar without looking too clinical. There’s quite a bit of bokeh swirl under some conditions however, something I personally find somewhat distracting. The price is fair and it’s almost exactly the same size as the ZM Sonnar. A really compelling option overall. (Note that the preceding version looks like a good choice overall too, but with much worse ergonomics, which to me makes it a lot less compelling).

An older Sonnar or Sonnar clone

The Sonnar design has been popular throughout the years since its introduction and there are plenty of lenses out there based on the design. A lot of them can be mounted on an M-mount camera though most require adapters. Depending on the lens in question there can also be some compatibility issues. The upside is mostly about getting a very pleasant performer at a real bargain price. The overall signature on display in the ZM Sonnar is generally present in these older lenses too, though in less refined form. The modern manufacturing techniques and coatings in the ZM iteration gives it advantages such as increased contrast and better resistance to flare. Still these older lenses offer quite amazing bang for your buck and can certainly be a good alternative for those on a budget.

7Artisans 50/1.1

This lens is an intriguing option from a new, up and coming Chinese manufacturer. Despite the ambitious specs the lens is priced exceptionally low and it’s one of the cheapest 50mm M-mount lenses available. The lens is based on the Sonnar design and replicates many of the positive traits of the ZM Sonnar in terms of output signature. The additional speed can obviously come in handy though comes at the cost of the lens being significantly larger and heavier – perhaps the most significant drawbacks of the lens. Still it’s a piece of kit I’d probably like to have a go with in the future, if only to get a feel for what an f/1.1 lens can do.



We drive up to our empty house late that night. Huddling together we try to keep warm as the radiators work. Waking up to a wonderful morning we finally feel like we’ve arrived.





Bottom line

It’s not too surprising that the ZM Sonnar stirred up some confusion when it was released a decade ago. It’s certainly not as balanced as the typical contemporary Zeiss lens and that seems to have taken people quite off guard. As a result the lens has a somewhat mixed reputation where reading reviews can leave you with the impression of a sort of special purpose, special effects sort of lens that’s only really suited for shooting portraits and a bit of a bear to use properly.

With a bit of perspective though that turns out to not really be the case.

Sure it doesn’t have quite the biting sharpness of a comparable double-gauss design. And there are some steps you can take to mitigate ill effects of focus shift. But in the grand scheme of things these aspects are a bit overplayed.

You can treat it pretty much like any other lens and still get great results. And while it’s true that it has some traits that makes it shine for portrait work, those traits don’t preclude the lens from making pleasant looking of landscapes, urban environments, objects, interiors, plants, animals, shoes, toasters or any other sort of subject you might enjoy shooting. In fact its signature is among the most appealing I’ve ever encountered and works well regardless of subject.


So while close scrutiny of the resulting images can sometimes reveal some minor objective shortcomings, to me that’s like missing the forrest for the trees in many ways. All the positive traits outweigh these small drawbacks and the overall output ends up unusually appealing much of the time. So what we have then is a lens that’s not just usable and practical, but even exceptional.

Beyond the appealing output there’s also plenty to like. The fact that it’s really quite fast despite being so compact makes for a wonderfully usable lens. The solid ergonomics and still pretty reasonable price only further sweetens the deal.

Overall it’s certainly become one of the standouts that I’ve reviewed since starting this site, as well as one of my all time favourites. It might not be perfect for everyones preferences, but it’s pretty damn close for mine.


Hamish Gills excellent review of the ZM Sonnar was what initially sold me on it and is pretty much required reading for anyone interested in the lens. Read the review on 35mmc



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All photos in this review were taken by me, using Leica M4-P, Leica M9, Leica M Typ 262 or Sony A7. All film was scanned on the Plustek 8200i. Exif-data is intact. Open any image in a new window for a closer look.

This review was updated in July 2021 to reflect some new findings (that there’s less pronounced focus shift across the frame), some reflections from shooting the lens on the Leica M Typ 262 as well as adding some more Alternatives.