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 [1].

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 [1]. 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 [1]. 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 [1].

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 [1][2]. Buyers should treat the LTM and M-mount Ultrons as separate lenses rather than mount variants of one design [2].

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 [1]. Color rendition is described as strong, and the lens is well controlled against flare except when pointed directly at a bright source [1].

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 [1]. This is one of the clearest differences from the later M-mount Ultron, which is sharper at maximum aperture [2].

Flare resistance Coatings keep contrast high in most conditions, with flare becoming an issue mainly in strong backlight [1].

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 [1].

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 [1].

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 [1][2]. The M-mount lens was also offered in two finishes, a brass-barrel silver version and a lighter aluminium black one [2].

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 [1][2]. Because the two are optically different, performance expectations set by reviews of the M-mount lens do not transfer to the screw-mount original [2]. 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.

Sources

• [1] Casual Photophile (Chris Cushing). Voigtländer Ultron 35mm f/1.7 Leica Thread Mount Lens Review. https://casualphotophile.com/2018/09/25/voigtlander-ultron-35mm-f-1-7-ltm-review/
• [2] phillipreeve.net (Phillip Reeve). Review: Voigtlander Ultron 1.7/35mm - punches way above its weight. https://phillipreeve.net/blog/voigtlander-ultron-11-7-35-mm-review/