Part 4.- There is nothing new under the Sun.
Standard Sonnar lenses had to adapt in order to survive in the 35mm arena. In the late 1960′s Zeiss reformulated the lens into a configuration of five elements in four groups with a slower speed of f/2,8 this was the Sonnar 40mm f/2,8 for Rollei 35 cameras. Despite such changes, the design principles of the original Sonnar are kept. A similar Sonnar construction was used in the 1981 autofocus point and shot camera Nikon “Pikaichi” L35AF 35 mm f/2.8; the 2003 Rollei Sonnar 40mm f/2,8 in Leica thread mount; and with an additional rear element in the 2004 Zeiss C Sonnar T* 1.5/50 ZM in Leica M mount. It is worth noticing that with the Pikaichi Nikon was able to create a wide-angle lens (35mm) from the Sonnar design which is unfit by nature for wide-angle lenses.
Lens design for the Nikon “Pikaichi” L35AF 35 mm f/2.8
Based on the original Sonnar 50mm f/2 configuration (six elements in three groups, with a single positive lens in the first group, a cemented triplet in the second group and a cemented doublet of negative and positive elements in the rear group), the new Sonnar lens was integrated with the third element substituted by an extremely low-refractive-index material, that is, air. The three-element cemented lens was an excellent invention to reduce the interface with air, which contributed to the realization of a lens system with increased transmittance and minimized ghost in those days when the antireflective coating on the lens surface was not available. However, in the age of advanced coating technique, the need for a cemented lens was obviated. Then, the second lens was removed and the four group five element system configuration was developed.
Sonnar design C Sonnar T* 1.5/50 ZM
Since then, the Sonnar name (though not actually meaning a Sonnar design) has been used to designate the prime lens of some 35mm compact cameras such as in the Contax T series, being normally found in the five element in four group configuration, with max aperture of f/2,8.
The renaissance of the rangefinder system in the early 2000, brought two new “real” Sonnar standard lenses compatible with the Leica M mount, the Rollei Sonnar 40mm f/2,8 released in 2003 which followed the same lens configuration of the Sonnar design used in Rollei’s 35 cameras from the 60’s-70’s; and the Zeiss 50mm f/1.5 C Sonnar ZM announced at Photokina on September 2004. The Rollei follows specifically the reformulated design from the late 1960’s; on the other hand the Zeiss C Sonnar design consist of six elements in four groups, with a positive single element in the first group, an air-spaced glass instead of a cemented triplet in the second group, a negative single element in the third and a cemented triplet similar to the original Sonnar 50mm f/1,5 in the rear group.
From mid 2000’s the mirrorless interchangeable-lens system has been gaining terrain in the photographic arena. The mirrorless system cameras allow using the old Sonnars with Leica Thread Mount and Contax mount through the use of an adaptor. By having no flipping mirror the SRL technical barrier has been surpassed and new standard lenses of Sonnar designs may appear once again for this format.
It finally seemed that this was going to happen when on December 2011 Sony partnered with Zeiss to launch the Sony Carl Zeiss Sonnar T* E 24mm f/1.8 ZA for the Sony Nex system.
Unfortunately this lens is not a Sonnar design, it only bears the Sonnar name which is more a marketing strategy, Sonnar here means that it is a high-grade, light-sensitive lens. This lens features a construction of 7 groups in 8 elements (2 aspheric surfaces, 1 ED) and has a focal length equivalent to 36mm on the 35mm format.
With the new optical advances and the race to obtain the utmost sharpness from an objective it is very difficult that standard lenses with the Sonnar design will be developed and released to the market.
Standard Sonnars are native to 35mm rangefinder photography and you may only fully exploit its attributes with a rangefinder camera; that symbiosis is particularly seductive, it is the combination used by the early photojournalists, it is classic, a high mark of optical engineering, an unique expression of character, that is the photographic approach that I have embraced, that is the raison d’être of the Sonnar Summer.