Carl Zeiss

Carl Zeiss AG is a German manufacturer of optical systems and optoelectronics, widely regarded as one of the most historically significant names in photography. For the Leica M-mount community, the brand's relevance is centered on the Zeiss Ikon ZM system. Launched in 2004, this product line reintroduced Zeiss optics to the rangefinder market after decades of absence.

The ZM lenses are famous for their T (T-Star) anti-reflective coating*, which produces a distinct visual signature characterized by high micro-contrast, saturation, and flare resistance, often referred to by photographers as the "Zeiss 3D Pop." Unlike Leica's own lenses which often prioritize a gentle transition to out-of-focus areas, Zeiss ZM lenses are typically engineered for clinical sharpness and "bite." While the lenses are designed in Germany, the majority are manufactured in Japan by Cosina, the same facility that produces Voigtländer optics, allowing Zeiss to offer premium performance at a price point significantly lower than Leica [1].

History

The history of Zeiss in the rangefinder world is defined by its historic rivalry with Leica.

The Historic Rivalry (1932 to 1960s)

In the early 20th century, Zeiss Ikon (a conglomerate formed in 1926) was Leica's primary competitor. Their Contax rangefinder cameras were technically superior in many ways to the Leica screw-mount cameras, featuring a longer rangefinder base and a bayonet mount. However, following World War II and the partition of Germany, the Zeiss brand was fractured between East and West, and the company eventually exited the rangefinder camera market to focus on SLRs (Contarex/Contax) and medium format (Hasselblad) systems.

The ZM Revival (2004 to Present)

In 2004, Zeiss surprised the industry by partnering with the Japanese manufacturer Cosina to launch the Zeiss Ikon ZM, a film rangefinder camera that used the Leica M bayonet. This camera was arguably the most advanced M-mount film body ever made, featuring a massive viewfinder and an electronically controlled metal shutter. Alongside the camera, Zeiss released a complete line of ZM lenses. While the camera body was discontinued in 2012, the lenses remain in production and are widely considered the primary "premium" alternative to native Leica optics [2].

Product Lines (ZM Mount)

Zeiss categorizes its M-mount lenses by their optical design formulas rather than strictly by focal length.

The Biogon (Wide Angle)

The Biogon is a symmetrical wide-angle design known for having virtually zero optical distortion.

• Biogon T 21mm f/2.8 & f/4.5:* The f/4.5 "C" (Compact) version is legendary for its corner-to-corner sharpness and lack of distortion, making it a favorite for architectural photographers.
• Biogon T 35mm f/2:* Often cited as the direct competitor to the Leica Summicron 35mm ASPH. It is renowned for its transparency and high resolving power.
• Note on Sensors: Due to the symmetrical design, Biogon lenses have steep ray angles that can cause color shifts (purple fringing) in the corners on some digital sensors, though modern BSI sensors handle this better [3].

The Planar (Standard)

The Planar is the classic double-Gauss design that forms the basis for most standard 50mm lenses in history.

• Planar T 50mm f/2:* Widely considered the "reference" 50mm lens. It offers extremely flat field curvature and high contrast. Many users prefer it over the Leica Summicron due to its stronger flare resistance and significantly lower price.

The Sonnar (Classic Character)

The Sonnar design is famous for its compact size and distinct rendering.

• C Sonnar T 50mm f/1.5:* A deliberate throwback to the 1930s. The "C" stands for "Classic" or "Compact." This lens is not clinically sharp wide open; instead, it produces a dreamy, glowing look with smooth bokeh. It is notorious for focus shift, meaning the point of focus moves as the aperture is stopped down, requiring users to learn its specific behavior [4].

The Distagon (Fast Wide)

The Distagon is a retrofocus design used for high-speed wide-angle lenses.

• Distagon T 35mm f/1.4:* A large, complex lens designed to compete with the Leica Summilux. It uses a floating element (FLE) system to maintain sharpness at close focusing distances and is often tested as being sharper than its Leica equivalent, albeit significantly physically larger [5].

Technical Specifications

Feature	Specification Details
Native Mount	Zeiss Ikon Bayonet (Standard Leica M-Mount)
Manufacturing	Japan (Cosina): Most lenses (Biogon, Planar, C Sonnar). Germany: Select specialized lenses (e.g., Distagon 15mm f/2.8, Sonnar 85mm f/2 - now discontinued).
Aperture Clicks	1/3 Stop Clicks. This is a key difference from Leica lenses, which typically use 1/2 stop clicks.
Filter Thread	43mm (C Sonnar), 46mm (Most Biogons/Planars), 49mm (35mm f/1.4)
Lens Coating	T (T-Star)* Multi-Coating
Focus Coupling	Fully rangefinder coupled (0.7m minimum focus usually)

Market Reception

In the M-mount ecosystem, Zeiss ZM lenses occupy the "modern professional" niche.

• The "Zeiss Look": Photographers choose ZM lenses when they want high micro-contrast ("pop") and cooler, punchier colors compared to the warmer, gentler rendering of Leica or Voigtländer glass.
• Build Quality: While excellent, some users note that the "Zeiss bump" (a small nub on the focus ring) is less ergonomic than the concave focus tabs found on Leica lenses. Additionally, over long periods, ZM lenses have been known to develop "wobble" more frequently than their brass-heavy Leica counterparts.
• Value: Zeiss ZM lenses generally cost 30% to 50% of the price of their Leica equivalents, making them the primary choice for professional photographers who prioritize optical performance over brand heritage [2].

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Sources

• Zeiss Lenspire (Official History): https://lenspire.zeiss.com/photo/en/article/the-zeiss-ikon-zm-system
• 35mmc (ZM Lenses Overview): https://www.35mmc.com/25/11/2014/zeiss-zm-lenses/
• Phillip Reeve (Biogon 35mm Review): https://phillipreeve.net/blog/review-zeiss-zm-35mm-2-0-biogon-t/
• Steve Huff Photo (C Sonnar 50mm Review): https://www.stevehuffphoto.com/2010/02/25/the-zeiss-zm-c-sonnar-50-f1-5-lens-review/
• Jack Takahashi (Distagon 35mm f/1.4 Review): https://jacktaka.com/zeiss-35mm-f14