Peter Karbe

Peter Karbe & el Leica APO-Summicron-M 50 mm f/2 ASPH.

Peter Karbe es el actual responsable del departamento de óptica de Leica Camera AG desde el año 2000

La lista de objetivos que llevan su firma es impresionante:
Vario-Elmar-R 21mm 35 mm f:3,5 f:4,0 ASPH (2002)
Vario-Elmarit-R 28mm-90 mm f:2,8-4,5 ASPH (2004)
Summicron-M 28 mm f:2,0 ASPH (2000)
Elmarit-M 90 mm f:2,8 (2000)
Tri-Elmar-M 28-35-50 mm f:4,0 ASPH (II) (2000)
Elmarit-M 24 mm f:2,8 ASPH (2001)
Macro Elmar-M 90 mm f:4,0 (2002)
Apo-Telyt-R 1600 f:5,6 (2003)
Apo-Summicron 75 mm f:2,0 ASPH (2004)
Elmarit-M 28 mm f:2,8 ASPH (2006)

Peter Karbe, head of Leica optics design, has worked on the 50mm Summilux-M ASPH f/1.4 (according to roumor, he worked the lens design for ten years, and in his spare time), 75mm Summicron-M ASPH f/2.0 . As the head optics designer at Leica he has also had a great deal to do with the new Leica S lenses.

Here's an excert from a talk David Farkas of Dale Photography in Hollywood had with Mr. Peter Karbe at Photokine in 2008:

"Sitting with Peter you really get the feeling that these lenses are his children. Talk of certain lenses puts a small smile on his face and a glint in his eye.

Then, he’ll go on about why it is special and unique. For instance, many know of his many years of work on the 50mm Summilux ASPH. He is extremely proud of this lens, pointing to the MTF-chart and exclaiming that wide open at f/1.4 it resolves 40lp at above 50%. He went into how he came up with the modified special double gauss design and how the back half of the lens is identical to the 35mm Summilux ASPH, while the front half is identical to the 50 Summicron. This was the secret to achieving such performance in a fast 50.

Then, he said that one Saturday morning over his first cup of coffee in his kitchen he thought about [Dr. Walter] Mandler. Apparently, after Mandler designed the Noctilux, he used the same design to build the 75 Summiux. And while Peter doesn’t like the 75 Lux , he decided that he needed to design a 75 based on the 50 ASPH design. Shortly thereafter, keeping everything the same, except for removing one lens element in the first doublet behind the central ASPH element used to correct for aberrations caused at 1.4, he minted the design for the 75 APO Summicron ASPH.
I asked if the design was the same why the 75 was an APO lens and the 50 wasn’t. Here is a bit of a shocker… the 50 lux ASPH is an APO lens, containing an APO correction element. But, he thought the idea of an APO 50 was a bit silly so they never put it on the lens or in any marketing materials.

He really believes in revisiting the past for inspirations on the future. Peter said that he often thinks about what his predecessors from decades ago would do with today’s technology. This was his inspiration with the Summarits. Classic designs with a modern twist. He studies and claims (who would doubt him) that he is familiar with the designs of almost all of the Leica lenses made to date. He has his favorites as well as examples that were not so successful.

According to Peter, the great leaps in lens design were brought about by technological advances. The first was with new types of glass, then with coatings, followed by computer modeling, and now just recently, advances in mechanical design and manufacturing. This is why the S lenses and the new 21 Lux are as lightweight as they are. A lot of attention is now being paid by the design team to the manufacturing process. Karbe has organized small design teams in his fast-growing department to be more efficient and productive. An optics designer is paired with a mechanical designer and a production manager to develop the entire product, not just the optical path. Handling, feel, ease of manufacture, and consistency in quality control are equally important to imaging performance. Also, by using more shared designs and more common components, more lenses can be brought to market faster. The 35 and 50 Summarit. The 75 and the 90 Summarit. The new 21 Lux and 24 Lux are all examples of this. With the 21 and the 24, one designer did both lenses simultaneously as they are fundamentally the same optical formula.

Another interesting thing I learned was that Leica started using computer-aided modeling back in the 1960’s before anyone else. Since that time, they have had their own proprietary software (kept up to date, of course) based on calculations made at Leica over the last 100 years. He says this is one of Leica’s real advantages that no one can copy. The foundation of knowledge and expertise is handed down from each generation of lens designers to the next. The Leitz Glass Works has also been invaluable in learning about new formulations and the handling of exotic glass elements. These latest exotic glasses require a great deal of care in handling. Much like a piece of raw steel, this glass reacts adversely and rapidly with gasses in the air. They use a wet to wet to wet process in Solms, whereby the glass moves through the grinding, polishing and coating steps in one go, not spaced or binned. This is crucial to maintain the performance of these expensive elements which can cost more per ounce than pure silver.

We talked more about how the type of glass for certain lens elements are chosen and how, based on his experience, he just knows what effect this will have on aberrations. We discussed the trade-offs lens designers have to make and how MTF only tells part of the story."

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