Voigtländer Ultron 35mm f/1.7 I

Voigtländer Ultron 35mm f/1.7 I

Among the fastest 35mm lenses ever offered in Leica thread mount, the Ultron 35mm f/1.7 was Cosina's bid to undercut Leica on speed and price at the close of the 1990s. Its f/1.7 maximum aperture was chosen specifically to edge past the f/2 Summicron, a piece of marketing positioning as much as an engineering goal, and it sits near the top of the LTM speed chart, behind only the rare Canon 35mm f/1.5 [1]. The lens was introduced around 1999 to pair with the early Cosina-built Bessa screw-mount bodies, and reviewers note how well the two were matched as a package, the black lens finish complementing the camera so closely that the combination handles like a fixed-lens rangefinder.

The optical layout uses eight elements in six groups with modern multi-coated glass, and incorporates two unusual features for a compact 35mm: an aspherical rear element to improve corner sharpness and control distortion, and a concave front element. Build quality is all-metal, with engraved markings and a half-stop click aperture ring running from f/1.7 to f/16, traits that reviewers say make the lens feel more like a vintage Takumar than a product of the Y2K era. The lens is rangefinder coupled and focuses to 0.9 m, longer than a typical SLR lens of this class but in keeping with screw-mount rangefinder norms. A screw-in hood with an over-hood cap was supplied.

The LTM lens is the first and optically distinct version, engraved "Aspherical" on the front and using a different focusing barrel from the later M-mount Ultron that Cosina released afterward. The two are not the same optical design, and several reviewers report that the original screw-mount version is neither as sharp wide open nor as high in contrast as the redesigned M-mount lens, which carries a different element count and a flatter field[2]. Buyers should treat the LTM and M-mount Ultrons as separate lenses rather than mount variants of one design.

Optical qualities

Rendering The LTM Ultron is generally regarded as a capable lens with some character at maximum aperture. Wide open at f/1.7 it is not the sharpest design and can look soft, but it tightens up quickly: by f/2 to f/2.5 and smaller, images gain noticeable bite and contrast. Color rendition is described as strong, and the lens is well controlled against flare except when pointed directly at a bright source.

Sharpness At f/1.7 the screw-mount version trades ultimate sharpness for speed, with reviewers and owners describing softer wide-open results that improve markedly on stopping down. This is one of the clearest differences from the later M-mount Ultron, which is sharper at maximum aperture.

Flare resistance Coatings keep contrast high in most conditions, with flare becoming an issue mainly in strong backlight.

Collector and user notes Owner opinions vary, with some praising the lens as usable wide open and others confirming the softness at f/1.7 in controlled tests, which may reflect sample variation.

History

Development and Launch Cosina revived the Voigtländer name in the late 1990s and built a line of affordable rangefinder lenses around its new Bessa cameras. The Ultron 35mm f/1.7 in Leica thread mount appeared near 1999 as a fast normal-wide option, positioned by its speed and price against Leica's more expensive 35mm offerings.

Production Evolution The screw-mount Ultron was later joined and effectively succeeded by an M-mount version of the same name. That later lens is a different optical computation rather than a simple rehousing, with reviewers reporting changed element and group counts, improved wide-open sharpness, and higher contrast, alongside a revised focusing ring. The M-mount lens was also offered in two finishes, a brass-barrel silver version and a lighter aluminium black one.

Collector Notes The most common point of confusion is mistaking the LTM Ultron for the later M-mount lens, since both are sold as "Ultron 35mm f/1.7 Aspherical." The screw-mount version is identified by its thread mount, "Aspherical" front engraving, and distinct focusing barrel, and it generally sells for less than the M-mount lens on the used market. Because the two are optically different, performance expectations set by reviews of the M-mount lens do not transfer to the screw-mount original. As with any multi-element rangefinder lens of this era, buyers should check the glass for haze and confirm the supplied hood and caps are present.