Leica Lens Saga
Erwin Puts’ latest volume explores the progression of Leica 50mm lens design from the original Anastigmat/ Elmax/Elmar lenses of the Leica I to the most recent optical masterpiece from Leica, the APO-Summicron-M 1:2/50 mm ASPH. Erwin presents a thorough view of the entire process. He explains optical theory, methods of lens design, ray tracing, aberrations, how to evaluate lens performance and its relationship to image quality, etc. to name a few of the topics addressed in this book. To say Erwin’s explanations are quite thorough would be an understatement. This is a complex subject which demands equally complex explanations to fully understand the given subject matter. The reader needs to devote the proper amount of time to this book to fully benefit from the insights it has to offer. Not exactly the kind of book to be described as light reading.
I have only had the book for a few weeks, so I will look at some of the highlights contained in the book. To read the book cover to cover would require quite a bit more time than that I have available to write my review! If you are an optical designer, I’m sure most of the information on optical theory and design will be second nature. However, to us mere mortals, there is some real heavy going here.
Max Berek’s name is not quite as well-known as that of Oskar Barnack in the story of the Leica, but he certainly played a critical role in the Leica’s success. Berek was primarily concerned with the design of microscope optics at Leitz, working extensively with the new field of polarized microscopy. In the world of optics, camera lenses are considered to be less of a challenge to design than microscope objectives, due to the smaller size of the microscope objective and higher levels of precision required in their manufacture. Puts gives some valuable insight into the task faced by Berek to design the first lens for the new Leica camera. He explains how Berek arrived at the focal length of 51.9mm and an angle of view of 45 degrees were chosen for the new camera’s lens. This was done for some very pragmatic reasons according to Puts. The aperture of f/3.5 was considered to be the fastest practical aperture to use on the new camera. This was considered a relatively fast lens at the turn of the 20th century, given the very slow film speed of the emulsions in use at that time. The angle of view most likely had to do with Berek’s choice of panchromatic correction for his lens in a time when most lenses were corrected for orthochromatic emulsions. The panchromatic correction also had the bonus of being able to work well with the color film emulsions which would be introduced many years later. The narrower angle of view helped limit aberrations and cropped out the relatively soft edges of the Elmar design, a shortcoming Berek was well aware of. The choice of an f/3.5 aperture also provided an extended depth of field and an essential safety factor for the relatively inexperienced photographers of that time in dealing with the new miniature format. Today we take the integrated viewfinder/rangefinder for granted, but with the Leica I, the user had no such luxury. The camera was scale focused, either by guesstimating the distance to subject and setting it on the lens, or using an auxiliary focusing device mounted in the accessory shoe such as the FOFER and transferring the indicated distance onto the lens. Even if the user misjudged the correct distance, he was assured of high quality images. As a new product, it was essential that the Leica succeed in the marketplace, and the new user should not be disappointed with the results while he was experimenting and learning. These are typical of the insights Erwin provides throughout the book, which gives the reader a real appreciation of Berek’s talent as a designer and ability to overcome many formidable obstacles to make the Leica a success.
Puts takes us through the design process used at Leitz by Berek and his successors for the subsequent development of interchangeable lenses for the Leica. New glasses and technology such as lens coating, the advances made in mechanical precision and the insight into optical design gained over many years’ experience helped make each new design perform better, work in lower available light, etc. over the course of the past ninety years. The maximum aperture milestones of f/2.5, f/2, f/1.4, f/1.2, f/1 and f/0.95 were all achieved over these years. In Berek’s day, lens designs were done with the use of the slide rule and logarithmic tables. The thousands of calculations were performed by human “calculators”, usually women, after the chief designer came up with his initial design. The design was then verified or changed depending upon the result of these calculations. This method lasted well into the Thirties with the advent of electrical and mechanical desk calculators. This was the first generation of lens designs at Leitz, with the Elmar and Hektor designs by Berek and the Summicron I and Summilux I by Zimmermann and Kleinberg. The second generation came with the introduction of the first digital computer at Leitz with the Zuse 5 in 1952. At this time, the new version of the Elmar 2.8/50, second generation Summicron (Rigid) and Summilux II were designed. Mandler and Marx were some of the wellknown names associated with these designs. In 1958, the Zusewas succeeded by the more powerful Elliott 402 computer, which was used in the design of the Noctilux 1.2/50 designed in 1966 by Helmut Marx and Paul Sindel. In 1968, the IBM 1130 computer with its POSD optical design program came into use at Leitz, and Dr. Marx improved upon the IBM program with his COMO design program. This was used by Mandler to design the Summicron III 50 and the Noctulux 1/50 mm lenses. The third design generation under Lothar Kölsch and Peter Karbe are characterized by the Tri-Elmar-M, 50 Summilux ASPH and the Apo-Summicron 2/50 ASPH FLE. Coupled with improvements in manufacturing at Leica through such innovations as CNC machining, molded aspherics and much tighter manufacturing tolerances and quality control has allowed these cutting edge optical designs become a reality. The fourth generation of lens design is just dawning at Leica, with what Puts calls the “mechatronic” (mechanical and electronic hybrids) age. These designs are those for the S-lenses and the T, Q and SL designs recently introduced by Leica.
Overall, I would recommend this book to the serious Leica photographer or anyone interested in the history of lens design at a leading optical house such as Leitz/Leica. There are diagrams showing the internal details and ray paths of the lenses being discussed, as well as MTF Graphs, Seidel Listings and Spot Diagrams. These are all welcome and help to understand the comparative performance of these lenses. I cannot recall any other author making all of these analytical illustrations available in one place, and Erwin is to be congratulated on this. I cannot argue with the inclusion of Erwin’s very thorough explanation of optical theory and design. After all, if one is to truly understand the subject, one must understand the science and theory behind it. But, as I stated in the beginning of this review, it is slow going and for many readers it will prove to be very difficult reading as well. Having a background in the subject would certainly benefit the reader. This book is not a casual read by any means, but if you take the time to understand the subject through Erwin’s tutorials, you will be rewarded. The minimal captioning and lack of any figure numbers for the illustrations to refer to from the text is not helpful to the reader. Erwin has included a twenty-eight page section of images to illustrate Leica lens quality with the cryptic introductory paragraph stating that they were made with the current 50mm lenses made by Leica. Unfortunately, no further information is given for each image, so we are left to guess which lens made which image. A little more information here would have made a lot of sense, and it is puzzling why this data was omitted. There are several minor typos in the text, but given that English is Erwin’s third language, I think he does quite well with this difficult subject. I would say that the insights into the design process employed by Berek and his successors at Leica for their landmark lenses are well worth the price of admission. The Annex section with brief descriptions of the highlights of each 50mm lens design in chronological order is highly enlightening and useful for quick reference.
The Vulcan bombers, a cold war era aircraft, were built at a factory not far from my home. Some years after the Vulcans were retired from service XH558 was restored to flying condition for a while but this particular flight was its last. As part of a farewell air showtour a flypast over the factory was arranged. The image is from around half the full frame.
Spitfire MkIIa P7350 took part in the Battle of Britain and is believed to be the oldest Spitfire still flying. It was only at the last minute that I discovered between Air Show appearances that it was doing a fly past at an RAF base that we were visiting. This image is from a 9MP portion of the full frame.
MTF curves for f/3.4
MTF curves for f/5.6
Erwin’s book is available for purchase directly from him through his website www.imx.nl don’t suppose that I am the only committed Leica M user to admit that the 135mm focal length has never been the most frequently used of my M lenses. The direct vision rangefinder camera has many strengths but of course, there are genre’s for which the M will never be as convenient to use as an SLR and for some subjects it is not very practical at all. Nevertheless, I’ve always considered a 135 to be an important part of my ‘M’ outfit. It has become even more necessary now that my photography is concentrated primarily around the M rangefinder system.
Following the demise of the R system, the live view facility that came with the M240 has given new life to some of my favorite R lenses. However whilst I have become comfortable using my 100 Apo-Macro–R with the EVF for relatively static macro and studio subjects the shutter lag has inhibited the use of my other favorite, the 180 f/2.8 Apo-Elmarit-R, that I always liked for action photography.
Fortunately, since the advent of an 18 megapixel, full frame sensor with the M9 and now 24 megapixels with the M240, I have realized that it is possible to quite severely crop the frame and still obtain high quality images. With my 135mm, Apo-Telyt-M, I reckon that the equivalent of a 200mm lens is available in rangefinder mode on my M-P. In this mode, there is never any loss of the subject in the viewfinder and no shutter lag so that I can precisely time my moment of exposure and continue tracking during a ‘panned’ shot. This is a great help and works well for most of the aircraft photography that is an interest of mine. It is very convenient that I can now carry just one Billingham bag with a compact M outfit that effectively ranges from 18mm to 200mm.
The optical construction of the 135 Apo-Telyt–M.
LOOKING BACK
There were good reasons why Leica even from the very early days, limited the application of rangefinder focusing to a maximum focal length of 135mm. The comparative accuracy of rangefinder focusing system- unsurpassed with wider angle lenses begins to decline significantly as you reach 90mm and beyond,-just when you really need greater accuracy. The demands on the mechanical precision of both the camera and lens focusing systems are compounded by the need for a good standard of eyesight and by rapidly reducing the depth of field. The relatively small viewfinder frame for this focal length can sometimes make good composition more difficult too. In all respects good results from a 135 need care and practice.
Following the M3 Leica redesigned the rangefinder for the M2 and it has been this M2 design that has been the basis for all subsequent M models. Unfortunately in order to accommodate the 35mm frame in the M2 the rangefinder magnification was reduced from 0.92 times to 0.72 times (and later to 0.64 times in the digital M cameras). At the time of the M2 this was not considered accurate enough for a 135 lens and the 135mm frame was eliminated for that camera. It was reinstated however for the M4 and later bodies other than the M8. An option introduced for the M2 was the 135mm f/2.8 Elmarit that had ‘goggles’ that magnified the viewfinder and rangefinder image 1.5x so that the 90mm frame was suitable for a 135mm lens. It was a neat solution that increased both focusing and framing accuracy. I used an Elmarit extensively on my first Leica an M2 and found it to be a very good lens.
Despite its advantages, the f/2.8 Elmarit is heavy and bulky and when the M4 came along with its 135 frame, I swapped the Elmarit for the much more compact f/4 Tele-Elmar. This is a truly excellent lens and mine served me well until I changed it for an Apo-Telyt-M when this lens was introduced in 1998.
There is a viewpoint from a hill above the town of Cochem on
the Mosel river in Germany. I had to wait some time for a brief patch of
sunlight to illuminate the castle. The M-P together with the 135 APO Telyt is compact, easy to handle and still reasonably light
THE APO-TELYT-M
The 135 APO-Telyt is a superb lens, one of Leica’s very best M lenses to date. The MTF graphs demonstrate just how exceptional the performance is. Performance at full aperture of f/3.4 is remarkable and very even across the full field of view. There is a slight increase in the contrast of fine detail when stopped down to f4/f5.6. Distortion (pincushion) is minimal and for practical purposes non-existent. Vignetting at full aperture is just over half a stop but this is all but eliminated by f/5.6. The optical construction is 5 elements in 4 groups with no aspherical elements and no floating elements are needed to achieve the exceptional performance.
The lens’s technical specification is fully supported by practical results. Clear crisp images of the highest quality with clean subtly nuanced color rendition are the trademark of Leica Apo lenses. The 135 Apo-Telyt-M is no exception. Performance in the near range is very good and there is notable freedom from flare.
With a Leica M it is quite a compact unit and the handling is comfortable. The only proviso is that to get the best from this lens good photographic technique is especially necessary. Depth of field is minimal, so accurate focusing is essential. Careful exposure in order to avoid ‘blown’ highlights and avoidance of camera shake and subject movement are prerequisites.
This owl is one of the birds at a wildlife nature reserve. It has quite a large cage and I needed the 135 to get a reasonable shot. Focus was on the eyes notice that with the limited depth of field the beak and claws are out of focus.
TECHNIQUE
Given good technique, I have been surprised at just how high the quality is even when an image is cropped to use only 12mp of the 24mp on my M-P. For practical purposes, I really do have a 200mm lens available. For many action shots of sports activities, aircraft, motor racing, etc this is adequate for my needs. I do not miss carrying around a bulky, heavy SLR. My lens is a fairly early version and not 6-bit coded so I have one of my profiles set-up for it. I also have this profile set to ISO 400. Camera shake can be a real problem with longer lenses so I like to use a minimum shutter speed of at least 1/500 second with a 135. The camera is also usually set to ‘A’ and the lens at f/5.6 or f/8. In reasonable light, this provides a shutter speed at least as fast as this. For aircraft shots and motor racing, I like to set an aperture that ensures a minimum shutter speed of 1/1000th second so the lens is often set at f/4 or f/3.4 which in reasonable light will give a speed of 1/1500th or even 1/2000th sec. Of course focusing a moving target is not easy without autofocus so, whenever it is possible, I prefer to pre-focus on the spot where the main subject interest is expected to take place.
For landscape and other relatively static subjects perfectionists would argue that a tripod (used with live view if available) is the answer. This is true, but for me this approach can defeat the many advantages that the M’s compact easy portability offers. Today’s higher ISO speeds are well capable of good quality images and in many situations can negate the need for a tripod. Another option to improve focusing and framing accuracy is to use a 1.25X or 1.4X magnifier.
CONCLUSION
At the start of this article I indicated that the 135 APO is probably the least frequently used lens in my kit but I would not want to be without it. There are subjects for which a 135 is the best answer. In these instances the Apo-Telyt–M will deliver outstanding images. A certain degree of practice is needed to get the best results but the image quality it is capable of is exceptional. I have the same confidence in its performance that I have with my 50mm Apo-Summicron and the 35mm Summilux FLE. With this lens included my M outfit satisfies almost the complete range of my photographic requirements.
Finally, I would mention that if the cost of an Apo-Telyt-M is not justified for infrequent use, you should be able to find a good second hand Tele-Elmar at a modest price. It’s not quite an Apo-Telyt but you will be impressed by just how well it does perform!
The M is an ideal camera for panned images; you never lose the image in the viewfinder as you follow the subject.
Touchdown shots at our local airport require a day with one of our infrequent easterly winds. I wanted to capture the puff of smoke as the tyres touch the runway. The M with direct vision helped to get the timing right
Again the M in direct vision rangefinder mode helped me to get the timing right- just as the competitors were clearing the last line of hurdles for the sprint to the finish line.