Jim Cheung

Rollei 35 的四種鏡頭

Monday, May 24, 2010

曾經有 Tessar (Original) 和 Sonnar (SE), 我個人更喜歡 Tessar 出來的顏色和硬度, 現在只留下兩部 Tessar.

Four different 40mm focal length lenses were used on various model variants:
f/3.5 Triotar
f/3.5 Tessar
f/3.5 S-Xenar
f/2.8 Sonnar
f/3.5 Triotar
The Triotar is a single coated Carl Zeiss design using three elements in three groups based on the Cooke Triplet. I have been unable to date its design by Carl Zeiss. The concept for it dates to the late 1800's. The lens design has been used extensively by Carl Zeiss to produce an inexpensive, optically simpler alternative to the other more expensive lenses of similar focal length. Its three element design makes is much more susceptible to astigmatism. Hence this lens was used on Rollei's lower end models.
In spite of limitations it is still a good lens design with has very good contrast and resolution. Compared to many inexpensive P&S cameras on the market today, it is still a better lens. Collectors do not prize the Triotar models as highly as the others, nor do definitive users. As a result the price on a Triotar model is much less than for one with a Tessar or Sonnar, or even an S-Xenar. Some of this is due to the lens and some due to the fact the body was simpler with fewer features. Models made with the Triotar were an effort by Rollei to provide a less expensive alternative to the Tessar lensed models and capture greater market share.
f/3.5 Tessar
The Tessar is also a single coated Carl Zeiss design using four elements in three groups. The Tessar design by Dr. Paul Rudolph dates to 1902 and was originally used on large format view cameras. It is based on the Cooke triplet with an additional lens element. The first was an f/6.3 which is quite slow compared to modern lenses. By 1917 successive efforts including those from other Carl Zeiss engineers raised it to f/2.8 which is the fastest I have found on primarily pre-W.W.II cameras. The f/2.8 Tessar was used extensively by Zeiss Ikon on many of its 35mm models. As the patents ran out in 1920 the Tessar became one of the most copied lens designs of the 20th Century. I found no less than twenty-one major lens manufacturers that have used this lens under a variety of names. It is relatively simple, has exceptional resolution and extremely high contrast with low distortion in a flat field. The one drawback to the Tessar is its limitations for very fast lens designs. Carl Zeiss never implemented it at faster than f/2.8; virtually all post-W.W.II implementations are f/3.5 which is acceptable but slower than more modern lens designs allow for a standard lens. Nevertheless its basic design is still heavily used.
Very early "Germany" 35's used Tessar's made by Carl Zeiss. After that, Rollei obtained licensing to produce the lenses themselves. An unusual provision in the license allowed use of the Carl Zeiss lens name. While collectors might prize a Carl Zeiss Tessar model, there is no detectable difference in materials, build quality or optical performance between the Rollei and Carl Zeiss versions. Rollei's quality control was quite high.
f/3.5 S-Xenar
The S-Xenar is one of the rarer lenses found on Rollei 35's made during two production years in 1972-1973. It is a single coated Tessar clone by Schneider-Kreuznach. During the early 1970's Rollei wanted to bring its pricing down and the S-Xenar was less expensive. When Schneider could not meet delivery schedule for Rollei production requirements, Rollei dropped the S-Xenar and went back to producing the Tessar under its Carl Zeiss license. As with the practical difference between the "Germany" and "Singapore" models, consensus among long time users finds no difference in materials, build quality or optical performance between the Tessar and S-Xenar. Collectors however downgrade the pricing on an S-Xenar model. Schneider-Kreuznach is also one of the finest German lens makers ranking possibly second to Carl Zeiss. Today Schneider-Kreuznach is noted for exceptional cinema and projection lenses.
f/2.8 Sonnar HFT
The Sonnar is the best and fastest lens used on the Rollei 35's. It was designed by Carl Zeiss with five elements in four groups and has Rollei's HFT multi-coating. The Sonnar is one of the finest lenses of the 20th Century designed in 1930 by Ludwig Bertele, one of the finest lens designers of the 20th Century. Bertele originally worked for Ernemann, one of the premier German optics houses. When Ernemann was absorbed into the Zeiss-Ikon combine in 1926, Bertele began working for Carl Zeiss. The original was an uncoated f/2 5cm focal length with six elements in three groups specifically created for the Zeiss Ikon Contax. In 1932 it was reformulated for an f/1.5 5cm with seven elements in three groups. At some point after the Zeiss Ikon Contax IIa/IIIa ceased production in 1961, the Sonnar was reformulated into the configuration commonly found now using five elements in four groups for a slower f/2.8 lens. However, its design principles are essentially the same as the original Sonnar. The Carl Zeiss Sonnar has been used as the premier lens on numerous 35mm cameras. As with the Tessar, from the 1960's and beyond it is normally found in the slower f/2.8 five element, four group configuration.
Rollei wanted a faster lens for its top Rollei 35 model and Carl Zeiss reformulated the Sonnar using Rollei's HFT multi-coating resulting in the 40mm f/2.8 with five elements in four groups. It is a stunning lens noted for near zero distortion in its very flat field, very low falloff, exceptional resolution and very high contrast; all the attributes sought for in a superb lens. As with the later Tessar's the Sonnar HFT was manufactured by Rollei under license from Carl Zeiss. Compared to the Tessar, the Sonnar is a better, faster lens but is much more difficult and expensive to manufacture. The Sonnar has extremely tight tolerance requirements for its complex element shapes and their spacing. In spite of the age of its design, it is still a world class lens and holds its own quite easily with the very best of modern lenses

Source: http://johnlind.tripod.com/rollei/rolleitext.html