Super Wide-Heliar 15mm f/4.5 SL Aspherical

Cosina introduced the Super Wide-Heliar 15mm f/4.5 SL Aspherical in August 2003 alongside the 12mm f/5.6 SL, and the mount it was built in was Nikon F — not Nikon S. It is a symmetrical, non-retrofocus design whose rear group reaches so far behind the flange that on a single-lens reflex it will only go on with the mirror locked up: Cosina listed the Nikon F, F2, F3, F4 and F5 and the Nikomat series apart from the FS, all used mirror-up, while guaranteeing compatibility only with the F and F2. What earns the lens a place among Nikon rangefinder glass is an accessory rather than a version. Cosina’s F→S/C adapter ring — the FS adapter of English-language listings, ¥19,800 in Japan and $135 in the United States — breech-mounts to a Nikon S body, a classic Zeiss Contax or Cosina’s own Bessa R2S and R2C, and the lens then locks into the adapter’s own bayonet. No S-mount version of this lens was ever built. Every 15mm SL is an F-mount lens, and every one you see on a Nikon SP or an S3 is wearing an adapter.

The optics are the ones Cosina was already selling in Leica screw mount and in M mount; those are separate products with their own barrels and their own reviews, and Gandy’s account is that the SL differs from them in fitting and finish rather than glass. Eight elements in six groups, with one aspherical element added at the rear, give 110 degrees with the distortion, in Cosina’s phrase, corrected to the limit. There are ten blades and f/4.5 down to f/22 in half-stop clicks, and a minimum focus of 0.3m with detents at 0.5m and 1m — set it to 1m at f/8 and everything from half a metre to infinity is sharp, which is the point, since these are scale-focus lenses on every body they fit. The barrel is all metal, 63.5mm across and 12.8mm deep excluding the focusing lever, and weighs 150.5g; Jake Horn measured about 45mm overall once the part that disappears into the body is counted, which is the whole reason for the mirror. There is no filter thread at all, and Cosina noted plainly that the hood supplied with the L-mount model and its separately sold filter adapter could not be used. It sold for ¥75,000 excluding tax with a viewfinder in the box, or $459 from CameraQuest, which listed it at that price in December 2003; the finder stows in a shoe built into the rear cap, and an optional shoe base replaced the prism of a Nikon F or F2 to sit the finder directly over the lens and kill the sideways parallax.

Stephen Gandy, who imported the SL pair into the United States, thought the machining and finish ran ahead of the Leica-screw lenses built on the same optics, and he tested the obvious follow-on question himself: could the FS adapter be used to put ordinary Nikkor F lenses on a rangefinder? Mostly no — the adapter’s interior is largely occupied by the camera’s own focusing helical, and the protruding rear elements of his 20/2.8, 28/2, 50/2, 50/1.4 and 105/2.5 AI samples hit it, though a 50/3.5 Macro and an 85/1.8 went on. The Korean reviewer at Gigantoptik, shooting it on a Nikon SP and an S3 Olympic, reads the barrel as two homages stacked together: the dished front and the control layout from the Zeiss Hologon 16mm f/8, the colour-coded aperture figures from the F-mount Nikkor-O 2.1cm f/4. The verdict on the pictures is that the symmetry does what symmetry is for — verticals and horizontals line up straight once the camera is level, detail holds to the edges — while the falloff at f/4.5 is obvious enough to darken a sky into something like a polariser’s work. That review is also the one that describes the handling: a single knob works both focus and aperture, so changing the aperture means bracing the lens and pushing a little harder. Jake Horn made it his go-to travel wide on a Nikon F4 and accepted the trade, mirror up meaning no metering, no viewing and no filters; Tsuki (つき) bought one in 2009 for a Nikon F2 and a D700, where live view substitutes for the finder the locked mirror takes away, and titled the review “mount it and it’s a pancake”.

Cosina’s own product page still listed both SL wides at full price in February 2007, with the F→S/C ring on the accessory list at ¥19,800. By that May the ring had vanished from the page entirely and everything left on it — both lenses, the shoe base and the F→L ring — carried the line saying the product had been discontinued. Gandy’s page now heads the pair “Discontinued, Sometimes Available” and carries a standing wanted-to-buy notice for FS adapters. No production figure appears on Cosina’s pages or in Gigantoptik’s specification block, which leaves the count as a question mark. What survives is a small oddity of the rangefinder revival: a lens designed for rangefinders, built in a reflex mount so that reflex owners could have it too, and sold back to rangefinder owners with a ring in the box.