Introducing the Omnar 35mm f/3.5 Pantessa FLB

Re-housing Gives New Life To a Traditional Zeiss Tessar

Hermann Groeneveld / SilvergrainClassics

The Pancake Tessar from Omnar Lenses on a Leica M6 Camera

The Omnar 35mm f/3.5 Pantessa (short for Pancake Tessar), which is the subject of this article, was originally used as a Tessar 3.5/35 lens by Carl Zeiss in the Yashica T, T3, T4 and T5 Super cameras. Today, the T5 model in particular is a point-and-shoot camera that is highly prized on the second-hand market. It has an exceptionally powerful lens with a 35 mm fixed focal length for this class. The name Tessar stands for a truly outdated but still excellent lens design, which was already used in old plate cameras.

The Yashica T5 Super Point-and-Shoot Camera with the Tessar 3.5/35 Lens by Carl Zeiss

Re-housing Gives New Life to Vintage Lenses

This Pancake Tessar from Omnar Lenses, Worcester, UK, is a so-called re-housing. This term describes the process in which the complete optical system of an existing photography or film lens is installed in a new housing and fitted with the desired camera connections. In film and video production, this method is used to improve the performance and handling of a lens or to adapt it to the specific requirements of the film industry. This process is also very popular with vintage lenses, which have a special optical character that is intended to appeal to certain emotions in photography or film.

Focus Shift and Focus Breathing

There have already been various attempts to revive the Tessar lens and make it accessible to a broad community through re-housing. The unwanted phenomena of focus shift and focus breathing often stood in the way of a truly perfect optical solution for converted lenses for rangefinder cameras.

With focus shift, the focus point of the image can shift by stopping down, e.g. from f/2.8 to f/8. The originally focused area with an initially selected open aperture (f/2.8) is no longer exactly in the same position due to stopping down (f8). A lens usually consists of several optical elements that refract the light differently at different apertures. This can lead to a shift in the focus point. Incidentally, lenses with spherical lenses are more susceptible to this phenomenon than those with aspherical lenses.

With focus breathing, the focal length of the lens changes slightly when the focal plane is shifted. In other words, when the focus changes from a close object to a distant object or vice versa. As the focal length determines the size of the image angle, a change in the focal length results in the image section appearing to enlarge or shrink.

On an SLR system and on digital cameras with live view, focus shift and focus breathing are negligible. Sharpness and image detail can be reliably corrected before the shutter is released. This is more difficult with rangefinder cameras. The rangefinder may suggest a sharp image, but in reality it is out of focus.

Size Comparison: On The Left a Pancake Tessar From Omnar Lenses, On The Right a Leica M Lens

Floating Lens Block Enables Rangefinder Accuracy

The re-housing of the Pancake Tessar has a slightly modified optical formula compared to the standard Zeiss model: to counteract focus shift and focus breathing, the position of the optical block moves minimally within the lens housing when the aperture is adjusted. This intervention moves the glass elements of the Pancake Tessar into a continuously optimized position at every distance setting.

Omnar Lenses calls this new aperture-dependent optical repositioning Floating Lens Block (FLB). This unique design feature for re-housing enables high optical performance and rangefinder accuracy of the Pancake Tessar over the entire distance range from 0.65 meters.

Precise Brass Mechanics

The Tessar 3.5/35 from Carl Zeiss is one of the smallest 35mm rangefinder lenses ever made. Despite its small size, Omnar Lenses has succeeded in equipping the Omnar 35mm f/3.5 Pantessa with user-friendly focus and aperture control rings, as well as an E39 filter thread. In order to ensure precise focusing by moving the lens elements, the brass helicoid system was used in the mechanics of the lens. When focusing, the helicoid system moves the lens group along the optical axis via extremely precisely manufactured threads. The smooth movement of the mechanism is made possible by a brass construction. The material has excellent friction properties, robustness and durability.

Nevertheless, the Omnar 35mm f/3.5 Pantessa lens weighs only 108 grams. When mounted on a Leica M camera, the lens is smaller than a typical rear cap of the lens bayonet.

Leica M6 With The Pancake Tessar

Availability

The Omnar 35mm f/3.5 Pantessa FLB will not only be available for Leica M-mount. Further adaptations to digital cameras from Hasselblad and Fuji are planned. The lens is now available for pre-order on the Omnar Lenses website.

The first limited edition of this lens will comprise a total of 20 units. One copy will be made available to SilvergrainClassics for a detailed test. We will report on the results during the first quarter of 2025. Omnar Lenses expects all lenses produced to be ready for shipment by the end of February 2025.

Technical Specifications

Designation: 35 mm f/3.5 Pantessa FLB
Weight: 108 grams
Protrusion off camera: 16.5 mm
Aperture blades: 10
Distance measurement with a rangefinder camera from: 0.65 m
Minimum focus distance: 0.35 m
Optical formula: 4 element “Pancake-Tessar”
Image circle: ~60 mm
Price (approx.): 2,435 US dollars