The Perils of Lens Reviewing
Reviewing lenses is a perilous task. Unless one is using a full optical evaluation system and has the expertise to interpret the results, evaluations of the technical aspects of lens performance are anecdotal at best, and subject to the vagaries of the changing conditions of real world shooting.
I was a beta tester for, and for a while usedDxO Analyzer, the system that has since been adopted byChasseur DimageandPopular Photographymagazines. I stopped using it in my camera and lens reviews when I realized that the numbers and graphs generated only told me part of the story, and often not the part that I was most interested in.
So, what you get instead is my usual subjective, some would say biased, field evaluation. My testing is done by simply using lenses in the field, in this instance including with the 15mm Distagon inMarrakech, Morocco for a week in January, 2007. My evaluations were subsequently done through close evaluation of the image files on screen, but then primarily in prints. Most of my shooting was done with a Leica M8, and so the lens’ characteristics were evaluated within the context of that camera’s 1.3X frame reduction. I also tested the lenses on a Leica M6 and a Voigtlander R2A to evaluate the lens’ full-frame characteristics as well.
Nick Devlinassisted me in several of these reviews, and his comments and photographs are indicated separately.
Nick Devlinis a barrister and photographer in Toronto, Canada. He works as a Federal Prosecutor, specializing in major drug and extradition cases. With almost twenty years behind the lens, Nick worked extensively as a photojournalist and pro sports photographer before turning to the law. Presently, his main visual interests are urban landscape, portraiture and travel photography. He has been a passionate M Leica user for many years.
Nick’s Opening Observations
It’s no small irony that the digital age has brought such a previously unimaginable richnees of lens-choice for photographers using traditional Leica-mount rangefinders. I imagine this renaissance was largely born in reaction to the plasticization and automation which has swept mainstream camera design. It is wonderful that all these new lenses honour the silk-and-steel ethos which has always been a central feature of classic rangefinder cameras.
With its line of ZM lenses, Zeiss is attempting to occupy the middle-ground between Leica’s awesomely expensive optics and CV’s bargain-priced line-up. The challenge for Zeiss is that, while Leica’s pricing has left a lot of open real-estate in the market, the margin of quality between CV and Leica’s offerings is much more limited.
In the age of the M8, this gap narrows even further, since the M8’s 1.3 crop-factor discards the far edges of the image circle, which is where the men used to be separated from the boys, optically speaking.
My initial impression is that Zeiss has had mixed success in achieving the cost/quality balance that will make their line viable.
Similarly, the higher contrast and more saturated colours which the ZM’s produce on film is largely irrelevant with digital capture, as micro-contrast and saturation can effectively be increased in the processing phase, further leveling the playing-field between lenses.
In 2004 Carl Zeiss introduced the Zeiss Ikon ZM rangefinder camera and a range of lenses. These lenses, as with the ZM camera, use the Leica M series lens mount. These lenses started shipping in 2005. At first Zeiss used Hasselblad to distribute their ZM camera and lenses, in the USA at least, but this relationship came to an end, and since April 2006 Carl Zeiss is now distributing these themselves through a new sales organization which they have set up for this purpose.
The ZM camera is made for Zeiss by Cosina in Japan, as are most of the ZM lenses. The ZM camera is based on the Voigtlander Bessa body. (Cosina also makes Voigtlander branded rangefinder cameras and lenses, and is an OEM manufacturer to quite a few Japanese companies). Zeiss claims that though most of their ZM lens line is made in Japan, they are designed by Zeiss and made to their specifications and under their supervision. This is a similar situation to when Zeiss lenses used on Contax cameras were primarily made by Kyocera in Japan, with only a handful actually made by Zeiss in Germany, those being the most difficult to make, and therefore the most expensive.
Of the three lenses tested here, the 15mm Distagon is the only one made by Zeiss themselves in Germany.
Zeiss Distagon T* ZM 15mm f/2.8
Zeiss Distagon T* ZM 15mm f/2.8
Prior to theVoigtlander 15mm f/4.5 Aspherical Heliar, (reviewed here recently), the only 15mm lens this wide for an M Leica was the15mm f/8 Zeiss Hologonfrom 1972. It was sold by Leica, but only a few hundred of these very expensive and very slow lenses were ever made.
With the advent of the Leica M8, the need for what have till now been called ultra-wide-angle lenses has increased, because with a cropping factor of 1.3X, a 21mm lens, for example, is no longer effectively 21mm in terms of coverage. It’s a 28mm. But a 15mm, like the lens under discussion here, which on a film-based camera would be considered an ultra-wide, and thus of limited practicality and popularity, on an M8 becomes equivalent to a 21mm, a popular wide angle lenses for rangefinder shooting by some photojournalists.
Now that Zeiss is back in the game, selling M series lenses directly themselves, the 15mm Distagon becomes their flagship product, both in terms of price, design features, and attractiveness to M8 photographers. What’s it like?
This lens incorporates just about every high-end optical capability in Zeiss’ bag of trick, including 11 elements, with one aspherical surface, floating elements, and the use of several different exotic glasses. Of course at f/2.8 this is an extremely fast lens for its focal length, and the reason for this is seen when one takes the lens in hand.
Leica M8 with 15mm Zeiss Distagon
It’s big. Weighing in at some 500g, and with a 72mm front filter size, this is one of the largest M series lenses available, only exceeded by the Leica 50mm f/1.0 Noctilux, which in some ways it physically resembles. At a suggested retail price of $3,824 the 15mm Distagon also bears a price resemblance to the Noctilux. This makes it among the most expensive lenses one can buy for an M Leica.
Mechanically the lens befits the name Carl Zeiss. Fit and finish are absolutely flawless. The focusing ring turns with a buttery smoothness, and the aperture settings are in third stop increments that snick into place with a precision that one almost never sees any more, not even on Leica lenses. These third stop positions are so widely spaced apart that one could even set the lens to one sixth stop precision, (something that other reviews have noted as well).
There is a built-in petal-shaped lens shade, and the lens comes with a pressure-fit lens cap that fits over the permanent shade. A leather pouch and custom designed 72mm center filter to counter vignetting are also included.
After a few days of shooting with the 15mm Distagon in the souks and laneways of Marrakech I decided that though the additional stop of aperture was attractive over the f/4 Tri-Elmar wide angle, for example, the size of the lens on an M Leica was simply inappropriate – at least for the type of street shooting that is my main use for this type of camera. The whole thing is front heavy, it’s hand-holdability therefore is compromised, and the lens’ large front aperture makes it stand out, attracting unwanted attention.
My point of comparison is theVoigtlander 15mm Heliar, a lens costing a tenth as much, and dramatically smaller in size and weight (and maximum aperture). As good as the 15mm Heliar is, and it’s quite good, the Zeiss 15mm is clearly superior. It’s superiority can be seen even on-screen at small sizes, and with shots taken at an optimum aperture of f/8, let alone when each lens is at its widest aperture.
The Zeiss offers greater contrast and a subtle but clearly visible increase in saturation over the Heliar. It is also noticeably sharper, even when unsharpened raw files are viewed at normal screen sizes. It’s not that the 15mm Heliar is not good. It is. It’s just that the 15mm Distagon is simply superb.
When combined with the resolving power of the Leica M8 images seem to have an extra crispness, that while hard to quantify, is quite readily seen.
Leica M8 with 15mm Zeiss Distagon
The MTF charts below tells the performance story. (If you are not familiar with how to interpret an MTF chart you may wish to read my tutorial titledUnderstanding MTF).
MTF Charts for the Zeiss Distagon T* ZM 15mm f/2.8
For a lens this wide in full-frame the charts tell an outstanding tale. When you look at the left-most two thirds, which is what is captured on an M8, the performance becomes even more impressive. Note particularly how little things improve when stopped down from wide open to f/5.6. This tells us that the lens benefits little by stopping down, the sign of an extremely well designed lens to begin with, and certainly a characteristic that one wants when a significant premium is being paid for speed.
The 15mm Distagon is not rangefinder coupled, and because of its wide field of view requires an external viewfinder.
At a cost of about US $416, the accessory viewfinder for the 15mm Distagon is absurdly priced. It also is not the correct viewfinder if the lens is used on an M8. For this one needs a 21mm. TheVoigtlander 21mmviewfinder sells for $128 atCameraQuest, and to my eye is nearly as good.
Worth noting, in terms of viewfinder use, is that the bottom quarter of the view through the accessory viewfinder is blocked by the lens. One gets used to it, but there is a bonus. In addition to the detailed distance marking engraved on the focusing ring, in meters and feet, and with a depth of field scale and IR focus point, Zeiss has engraved a few additional focus distance marks on the lens at the forward end of the focusing ring, right up next to the aperture scale. What this means is that when looking though the accessory viewfinder one can see, and set, the focusing setting as well as the aperture ring. This turns the minus of the lens’ size, blocking some of the field of view, into a real plus. Both distance and aperture can be set with ones eye to the accessory viewfinder. Very cool.
To someone not familiar with accessory viewfinders, in these days of auto-everything-TTL-viewing-and-metering DSLRs, they may seen like an anachronism – a throwback to earlier times. Yup! They are. And it’s wonderful. Here’s why.
Using a rangefinder camera inherently allows one to see the scene without the restrictions of the view through a DSLR groundglass. This has been discussed here and elsewhere numerous times, so I won’t belabor the point. There are definite advantages when doing documentary style shooting.
Working with an accessory viewfinder moves this to an even more removed plane, because focusing is abstracted as well. With a very wide lens such as this, one zone focuses, sets the camera on a given exposure setting (or uses autoexposure if its appropriate and available), and then simply shoots. But the style of shooting usually means evaluating and anticipating the shot with the camera in ones hands, and usually away from the eye. Wait for the moment, anticipate it, and than quickly and as fluidly as possible bring the camera to ones eye, frame, and shoot. The camera comes away again and the shot is done. When done properly it’s remarkable how one can be part of a situation and yet be almost unnoticed as a photographer. An optical makes this work very efficiently.
If you don’tget it, that’s fine. But this is the style of working that photographers used for reportage, documentary, and street shooting for more than a half century, and it works exceedingly well.
Leica M8 with 15mm Zeiss Distagon
But – Why Not Rangefinder Coupled?
All of this begs the question – why isn’t the 15mm Distagon rangefinder coupled? As I wrote in my15mm Heliar review, which lens also isn’t coupled, it has to be either a matter of price or a technical limitation. Since the price of the Distagon, unlike the Heliar, can not be a factor, it would be interesting to know why the Zeiss lens isn’t coupled. This certainly will reduce the lens’ attractiveness for some potential users.
Subtle Blue Dots
No, not in the images – it’s on the lens mount. Whereas Leica lenses have red dots on the edge of the lens mount, to make mounting alignment easier, Zeiss’ ZM lens have blue dots. The problem is that in low light conditions, these are much less easy to see than Leica’s red ones. I’m glad they’re there, and they are better than Voigtlander’s markings, but Zeiss should consider making them a brighter blue. Subtle is good, but in this case diminishes practicality.
No Lens Coding
None of the Zeiss ZM lenses are coded, they way Leica lenses now are. The purpose of this 6 bit coding is to allow the M8, (and one would assume subsequent cameras) to make vignetting and other adjustments automatically.
If and when one does see vignetting this is easy to fix in either Lightroom, ACR or Photoshop (and hopefully future versions of Capture One as well). There is a an anti-vignetting filter provided with the lens as well. Hopefully though, Leica will see fit to update the firmware on M8’s to allow manual setting of focal length for vignetting correction, rather than replying solely on their 6 bit coding.
The Bottom Line
Is the Zeiss Distagon T* ZM 15mm f/2.8 the lens for you? Of course you’re the only one that can decide that. On the one hand, it’s physically large and very expensive. On the other, the image quality is simply superb. As good as I’ve ever seen form any wide angle lens, and right up there with Leica’s finest M series lenses. (Please Zeiss – make one in Canon EOS mount so more people can see what a great wide angle lens should be line).
Of course the f/2.8 maximum aperture will be important to some photographers, especially since my shooting experience corroborates the MTF charts. This lens is almost as good when used wide open as when stopped down – exceptional performance. Possibly as good as any ultra-wide angle lens ever made
How it will compare to the new Tri-Elmar with its16mm focal length remains to be seen, and will be discussed in my upcoming Tri-Elmar review.
Biogon T* 21mm f/2.8 ZM
Biogon T* 21mm f/2.8 ZM
The 21mm Biogon lists for about $1,324, while the 21mm f/2.8 Elmarit M Aspherical sells for about $3,500. I didn’t have the opportunity to compare the two. On the other hand the Voigtlander 21mm f/4 Skopar is about $350, including viewfinder (though the wrong one for M8 users). Quite a price differential all around.
In field use, as I did with the 15mm Distagon, I immediately saw similar characteristic differences between the Biogon and the Skopar. These included greater saturation, which one could also characterize as warmth, and in some ways a better colour fidelity. In terms of resolution the differences weren’t as pronounced but they were still visible on-screen, though only at 100% magnification.
This lens, like all of the ZM lenses except for the 15mm Distagon, is available in either black or chrome finish. There is a small focusing nub, which I find less appropriate than the well developed finger rest on all Leica lenses, but better than the screw-on lever which is provided with the 21mm Skopar.
Fit and finish of the Biogon was very nice, but it somehow felt a definite peg below the 15mm Distagon, which is right up there with any lens out of the Leica Wetzler factory. Maybe knowing that the Distagon is made by Zeiss in Germany, and the Biogon by Cosina in Japan has something to do with an unconscious bias.
In the end I wasn’t that attracted to the 21mm Biogon. I found its roughly thousand dollar premium over the 21mm Skopar hard to justify, especially since the Skopar provides 95% of the image quality for that saving. Of course the Biogon is an f/2.8 lens while the Skopar is an f/4. In the end, the Leica 21mm f/2.8 Elmarit is probably the one to have, even given its price premium.
The ZM21 performed very nicely for me. It is beautifully built and a pleasure to handle. It is, alas, rather large by rangefinder standards. Indeed, my only complaints are with the physical design of the lens. I found the ZM21 to be too long, being more than 25% longer than the Leica 21ASPH, and double the length of the CV 21. More problematic is the fact that this does not include any type of hood, which is a necessity given the wide angle of view and prominent front element. Also, with a lens this long, I would have preferred the focusing ring to be further forward, and less cramped into the body of the camera.
Leica M8 with 21mm Biogon
On the plus-side, I found the external CV 28mm viewfinder very easy to work with. (The Zeiss rangefinder was not available for this test, and in any event is too expensive). This was a pleasant surprise, as I had not used an external finder before and expected it to be a royal pain. To the contrary, I found myself preferring the eye-relief of the CV finders when using super-wides to squinting into the corner of an SLR viewfinder.
That said, Voigtlander has just launched the moderately revolutionary R4 camera, which features a built-in 21/35/28/35/50 finder. I’m sure that with the release of the 16-18-21 Tri-Elmar, and the profusion of wide-angle offerings from Zeiss, a similar wide-angle version of the M8 would find a large market.
Zeiss has obviously put some thought into differentiating its lenses from the competition. The blue mounting index dot on ZM lenses is one of the results, and I rather like it. While utterly unimportant, it gives the lenses their own character. The most obvious manifestation of Zeiss’ attempt to differentiate itself from the competition, however, is the choice to build the aperture ring with marked detents at 1/3 stop increments, rather than at the traditional 1/2 stops. This feature cuts both ways. On the positive side, it makes subtle exposure adjustments easier both when increasing or decreasing exposure manually, or when seeking to vary the shutter speed in Aperture-priority shooting. On the downside, it creates problems when one wants to vary the shutter speed or aperture manually, without changing the overall exposure, since the M8’s shutter control is marked in 1/2 stops. On balance, however, I like this feature, and would be happy to see other manufacturers adopt it.
The optical performance of the ZM21 was excellent. I shot with it wide-open much of the time, and was able to get pleasingly sharp results.
Leica M8 with 21mm Biogon
In my informal tests against the CV21, the lenses had matching center-resolution at all working apertures, though the ZM21 had perceptibly better resolution toward the edges and corners at f/4 and f/5.6. That said, the difference was small and only noticeable in a relatively close-up subject with very fine detail. By f/8 the two lenses were effectively identical in resolution. For daily use, I would take the CV21 over this lens on account of the size difference, notwithstanding the Biogon’s marginal quality advantage.
The attached photos – the cherub in front of the church, and the couple kissing by the steaming grate – show what a useful and versatile focal length 21mm is on the M8. This is no longer an exotic super-wide, but rather a core, everyday lens.
Many users will find the ZM21 an ideal comprise between the astronomically priced Leica 21ASPH and the slightly pedestrian CV21. Personally, the quality of this lens left me eager to try out its little brother, the ZM21mm f4.5 , which was announced at Photokina.
C Sonnar T* 50mm f/1.5 ZM
At a list price of about US $1,063 the 50mm f/1.5 Sonnar is a very interesting option. It’s direct competitor, the Leica 50mm f/1.4 Summilux M Aspherical, is regarded by many informed observers as possible the finest fast "normal" lens ever made. I’m fortunate enough to own one, and so it is my point of comparison for the Zeiss Sonnar. Voigtlander makes a 50mm f/1.5 ASPH Nokton which sells for about $350, so once again we have a large price spread. I have no personal experience with the Nokton.
Mechanically and in appearance the Sonnar is similar to the 21mm Biogon, and all ZM lenses except for the 15mm. It is available in both chrome and black finish. The "C" designation stands for "Compact" and indeed the lens is, being quite a bit smaller than the Summilux. The difference in aperture is less than a quarter stop, within manufacturing tolerances, so not really noticeable.
In my non-rigerous and highly subjective comparisons between the Sonnar and the Summilux I found the Leica lens to be superior wide open, but otherwise these lenses are both stellar performers. Just be aware that at f/1.4 and f/1.5 these lenses can be difficult to focus accurately. Even the tiniest focusing errors will be seen, because depth of field is very small indeed.
Leica M8 with 50mm f/1.5 Sonnar
I tried very hard to like this lens, because it is so nicely made. I shot with this lens wide-open much of the time, as the wide maximum aperture is itsraison-d’etre. Frankly, I don’t care how good it is at f5.6. Nowadays, anyone can build a 50mm lens that’s pin-sharp at f/5.6, and for far less money.
Unfortunately, in over a hundred frames I could only produce one sharp(ish) frame at f1.5. Fearing user-error, I went to the extreme of fixing my M8 on a tripod in broad daylight, focusing the lens with the absolute maximum precision I could muster on a subject 10’ away, and firing comparison frames on the self-timer. The results were still mushy.
My rangefinder is not miscalibrated, as frames shot at the same time on my sweet and tiny CV 40mm Nokton f/1.4 and trusty Leica 50 f2 were in focus. The real surprise was that the $349 CV lens simply blew the ZM50 away. (In fact, at f/2 it bested the 50 Summicron as well). (Nick and I confirmed this together on a second occasion. The sample of the Sonnar we had for testing lens is quite soft wide-open compared to the 50mm Summilux – MR).
From a design perspective, I really wish Zeiss had added a built-in hood similar to that on Leica 50mm lenses. Those hoods are the most elegant shade solution I have ever found, and could be easily copied.
Whenthe review of the 50mm Sonnar was first published there were some rather derogatory comments made on an online forum about our review, because of the concerns we had expressed about the sharpness (or lack thereof) of this lens when used wide open.
I had contact Zeiss about our finding and was told that the lens tested would be checked and also that the factory would be contacted for their feedback. Below is their response, confirming the appropriateness of our findings, and explaining why this is the case.
C-Sonnar T* 1,5/50 ZM
Information about special features for dealers and users
The C-SONNAR T* 1.5/50 ZM is a very special lens; based on a classical lens design concept from the 1930´s. The additional letter “C” in the name of the lens expresses this designation.
This lens design helps to achieve pictures with a special artistic touch. This lens ‘draws’ your subject in a fine, flattering manner and is therefore ideally suited for portraiture. It renders a sharpness that is slightly rounded, being less aggressive than in contemporary lens designs, but at the same time not soft in its rendition.
Many famous portraits of glamorous and prominent people during the 1930´s used this technique to great effect. These images are characterized by portraying the person in a shining, nearly celestial way. This effect is very well balanced and not exaggerated; therefore many viewers see it in a subconscious way. The trained observer, however, understands the underlining technique and enjoys the results.
This lens design exhibits some additional effects, which should be understood to achieve the maximum benefit from the C-Sonnar T* 1.5/50 ZM:
Because of the above mentioned classical characteristic of the lens the best focus position in the object space can not be kept exactly constant for all f-stop settings.
The passionate photographer might notice a slightly closer best focus in his pictures than expected. When stopping down the lens to f/2.8 or smaller this effect is minimized, so the focus position will be as expected.
In order to balance the performance at full speed and other f-stop settings the lens is adjusted with above described characteristic.
The special features of the C-SONNAR T* 1.5/50 ZM are best used in emotional, artistic, narrative images, portraits or atmospheric landscapes. For documentation or technical subjects CARL ZEISS recommends to stop down the lens at least to f/5.6 or to use the PLANAR T* 2/50 ZM lens.
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