Funleader Contax Planar 35mm f/2 Conversion V1

Funleader Contax Planar 35mm f/2 Conversion V1

The Funleader Contax Planar 35mm f/2 Conversion V1 is the first-generation non-destructive Leica M conversion of the Carl Zeiss Planar T* 35mm f/2 originally produced for the Contax G autofocus rangefinder system. Introduced by Funleader in collaboration with Mr Ding Studio, the conversion replaces the original Contax G focusing assembly with a dedicated manual-focus helicoid while retaining the original Carl Zeiss optical block.

The conversion is mechanically significant because the original Contax G lens was designed to be focused by the camera body rather than through a conventional manual lens helicoid. Funleader and Mr Ding developed a replacement housing that provides direct manual focusing and mechanical Leica M rangefinder coupling.

The original Carl Zeiss Planar T* optical assembly is retained without optical modification. It consists of seven elements in five groups, has a nominal maximum aperture of f/2 and uses the original seven-blade diaphragm. The front optical assembly also retains the 46mm filter interface used by the Contax G lens.

The V1 conversion should therefore be understood as a commercial Leica M rehousing rather than a newly calculated optical design. Its collector identity comes from the purpose-built focusing mechanism, M bayonet, exterior construction and association with the first Funleader and Mr Ding non-destructive conversion programme.

A contemporary owner measurement records approximately 206g for the conversion helicoid and 266g for the completed lens with the original G35 optical assembly installed. Reliable factory documentation for the precise external dimensions and minimum focusing distance of V1 has not been recovered, so those specifications should not be copied from either the original Contax G lens or the later V2.0 conversion.

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Optical qualities

Rendering

Because V1 retains the original Carl Zeiss G35 optical assembly, its fundamental imaging behaviour comes from the Contax G Planar T* 35mm f/2 rather than from a Funleader optical redesign.

An independent test of the V1 conversion on a Leica M-P Typ 240 found relatively neutral colour reproduction and strong central performance at wider apertures. These observations relate to tested converted examples and should not be interpreted as factory performance specifications.

Sharpness

The same independent comparison found the converted G35 notably sharp in the central image area at f/2. Corner performance at long distances showed more visible weakness at the largest apertures, with improvement after stopping down.

Mechanical calibration is important with any rehoused rangefinder lens. A poorly adjusted optical block or incorrect shimming can affect practical focusing accuracy even though the optical formula itself remains unchanged.

Bokeh and transitions

The original seven-blade diaphragm is retained. Independent V1 testing showed comparatively smooth out-of-focus highlights at maximum aperture, while more obvious diaphragm geometry appears as the lens is stopped down.

Distortion and vignetting

Independent V1 testing documented visible vignetting at wide apertures and some peripheral smearing at long focusing distances. The same testing showed improved corner definition after stopping down.

Digital use

V1 was designed specifically to make the Contax G35 optical block practical on Leica M cameras. Unlike a simple mirrorless adapter, the conversion provides mechanical rangefinder coupling and a conventional manual focusing interface.

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History

Development and Launch

The Carl Zeiss Planar T* 35mm f/2 was introduced for the Contax G system during the 1990s. The original lens used a proprietary Contax G bayonet and depended on the camera body's focusing system.

Interest in using Contax G optics on Leica M cameras led to several aftermarket conversion approaches. Some earlier conversions involved more permanent alteration of the donor lens.

In August 2019, Funleader and Mr Ding Studio introduced their first non-destructive G35 conversion system. The design allowed the original optical block to be removed from its Contax housing and installed in a dedicated Leica M focusing helicoid without permanent modification to the optics.

The complete conversion provided manual focusing and Leica M rangefinder coupling while allowing the optical assembly to be returned to its original Contax configuration.

Production Evolution

The first-generation conversion was produced in relatively limited numbers and eventually sold out. Funleader later reported continued demand for the system.

Rather than simply reproducing V1, the development team subsequently redesigned important mechanical aspects of the conversion. That work resulted in the mechanically revised G35 Conversion Kit V2.0.

V1 should therefore remain a distinct LeicaLensList profile rather than being overwritten by the later V2.0 specifications.

Special Editions/Variants

Contemporary examples document a black-paint version and a gold or brass-finish version.

The black-paint version was built over a metal housing capable of showing a warmer underlying metal as the exterior finish wore. The unpainted or gold-tone version used contrasting dark engravings and a black focusing tab.

No optical difference between these documented finishes has been established.

Collector Notes

The most common database error with this conversion is copying specifications from the unconverted Carl Zeiss Contax G lens.

The original Contax G lens weighs approximately 160g and focuses to 0.5m, but those are specifications of the original autofocus Contax G assembly. They should not automatically be assigned to the Funleader V1 Leica M conversion.

V1 is also distinct from Funleader V2.0. The later version retains the same basic G35 optical block but introduces a redesigned internal focusing mechanism, revised damping, a different external barrel and other mechanical changes.

The first-generation conversion also carries a strong historical connection with Mr Ding Studio, which collaborated with Funleader on the conversion system. That collaboration does not prevent the Funleader and Mr Ding commercial products from being catalogued separately when they represent separately marketed Leica M conversion products.

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Sources

• Funleader, Contax G35 Leica M Conversion Kit V2.0, product history and V1 developmentmyfunleader.com →
• Funleader, Contax G35 Conversion Kit V2.0, development historymyfunleader.com →
• Carl Zeiss, Planar T* 2/35 Contax G datasheetzeiss.com →
• The Owl Hollow, Funleader Contax G Carl Zeiss Planar T* 35mm f/2 reviewtheowlhollow.wordpress.com →
• Rangefinderforum, FUNLEADER Contax G35 F2 to Leica M Conversion reviewrangefinderforum.com →