Voigtländer Ultron 21mm f/1.8

Voigtländer Ultron 21mm f/1.8 Aspherical

When it arrived in 2012, the Ultron 21mm f/1.8 stood out as an unusually fast rangefinder-coupled ultrawide, offered at a fraction of the cost of comparable Leica optics. Marketed at roughly a fifth the price of the Leica 21mm f/1.4 Summilux, it filled a gap for M-system photographers who wanted ultrawide coverage with genuine low-light speed [1]. Although the Voigtländer name is German in origin, all modern lenses under the brand have been designed and built in Japan by Cosina since 1999, the same maker that produces optics for Zeiss [3].

The optical design uses 13 elements in 11 groups, including one aspherical element. The lens is rangefinder coupled, though its very wide angle of view, around 91 degrees, exceeds the framelines of most M cameras, so an accessory finder is commonly used. It focuses by hand only, with a closest focusing distance of 0.5 m, while rangefinder coupling tracks down to about 0.7 m. The 10-bladed diaphragm runs from f/1.8 to f/22 with half stops, and the aperture ring sits toward the front of the barrel, which takes some acclimation for users accustomed to a ring nearer the mount. The barrel is straight rather than tapered, an all-metal body finished in matte black anodizing, and the design includes a built-in, non-removable hood. Reviewers have judged build quality on par with the Zeiss lenses made in the same factory [2]. It accepts 58mm filters, is roughly 78mm long and 69mm in diameter, and weighs 412 g. The lens is not factory six-bit coded; on digital Leica bodies users have set it manually, with the 21mm f/1.4 or 21mm f/2.8 profiles suggested as a starting point.

The Ultron 21mm completed Voigtländer's run of fast M-mount lenses alongside the 28mm f/2, 35mm f/1.2, 50mm f/1.1 and 75mm f/1.8. It remained the brand's fastest ultrawide until the Nokton 21mm f/1.4 appeared in 2019.

Optical qualities

Rendering Documented reviews describe a strong optical performer for its class. Distortion is very low, reported as better controlled than other 21mm Leica-mount lenses tested, and falloff is mild, largely cleared by f/2.8. Sharpness is high even wide open, with little improvement on stopping down at the center, though corners trail Leica's slower 21mm designs. Flare and ghosting are well suppressed, even shooting into the sun on a digital M body.

Bokeh and transitions Out-of-focus rendering is considered pleasant. Cosina reportedly tuned the design for smooth backgrounds in the f/1.8 to f/2 range, and reviewers found defocused areas soft and undistracting, within the limits of how little a 21mm lens throws out of focus.

Aberrations Lateral chromatic aberration is cited as the lens's main optical weakness, more visible than on comparable Leica optics.

Digital use On digital Leica M bodies, peripheral color shift can appear in the corners and is best addressed by applying a lens profile, since the lens carries no factory coding.

History

Development and Launch The lens was developed by Cosina over roughly 15 months and announced in 2012 as part of Voigtländer's fast M-mount lineup. Tom Abrahamsson, who assisted with its development, noted that it was designed as a full-frame M-mount lens comparable in size to the 35mm f/1.2 while offering ultrawide coverage at high speed.

Special editions No major factory special editions or alternate mount variants of this lens are widely documented; it has been offered in black M-mount form.

Collector Notes Because the lens is not six-bit coded, buyers using it on digital M cameras should expect to assign a profile manually for corner color and falloff correction. The built-in hood is fixed, so there is no separate hood to verify, and the front accepts standard 58mm filters. Given Cosina's build standards, well-kept examples should remain serviceable, but as with any used lens it is worth checking the focus action, aperture clicks and glass for haze before purchase.