Japanese company Cosina has announced the Voigtländer Septon 40mm f/2 Aspherical, a manual-focus prime lens for full-frame Sony E-mount and Nikon Z-mount mirrorless cameras. The Septon name references a standard lens originally produced for Voigtländer’s Bessamatic and Ultramatic SLR systems in the late 1950s and 1960s: the new version adapts that designation to a compact lens designed for contemporary mirrorless bodies.

The lens is built around a six-element Ortho Metar optical design incorporating an aspherical element. It features a 10-blade aperture diaphragm and a maximum aperture of f/2. According to the manufacturer, the optical formula is intended to maintain consistent resolution across the frame at wider apertures while limiting chromatic aberrations and distortion. Both mount versions share the same internal construction but differ slightly in external design and dimensions.

The Sony E-mount version measures 30mm in length and weighs 165 grams, while the Nikon Z-mount variant is 32mm long and weighs 205 grams. The Z version features a scalloped focus ring, whereas the E-mount model uses a diamond-knurled pattern. Both lenses have an all-metal barrel construction and accept 52mm front filters.

With a 40mm focal length, the lens provides a field of view positioned between traditional 35mm and 50mm standards. The minimum focusing distance is 0.3 meters, resulting in a maximum magnification ratio of 1:5.3, and focusing is manual, using a precision-machined metal helicoid mechanism. Electronic contacts are integrated into the mount to enable communication with compatible camera bodies, allowing EXIF data recording, focus assist functions such as peaking and magnification, and support for in-body image stabilization where available.

Here are some sample pictures shot with both the Sony E and Nikon Z-mount versions, courtesy of Cosina: