MS-Optics Historio Prot 40mm f/6.3

The MS-Optics Historio Prot 40mm f/6.3 is a M-mount lens for Leica rangefinder cameras. Leica price index ↗

Reference maintained by Thomas Boots

Focal Length: 40mm

Aperture: 𝑓/6.3

Release Year (from): 2018

Diameter: 50 mm

Length: 16 mm

Minimum Focus Distance: 0.6m

Elements in Groups: 4/2

Aperture Blades: 10

Mount: M

Material Weight: Metal, 47g

Colors: Black

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MS-Optics Historio Prot 40mm f/6.3

Conceived as a working tribute to one of the oldest anastigmat designs in photography, the Historio Prot revives the symmetrical Protar layout that Paul Rudolph developed at Carl Zeiss, rebuilt by Sadayasu Miyazaki of MS-Optics for the Leica M rangefinder [1][3]. The "H" in the lens name stands for "History," and the Prot was the first entry in Miyazaki's so-called History Series, a run of homages to classic optical formulas that he laid out as a roadmap alongside planned Dagor, Ernostar and Petzval designs [2][3]. The result is a deliberately simple, slow lens of four elements in two groups, weighing only about 47 grams, that pairs an antique optical recipe with modern multicoating [1][3].

The barrel is unusually compact and shallow, roughly 16 mm deep on a 50 mm diameter body, with a small 22 mm front filter thread typical of Miyazaki's miniature lenses [3]. Like most MS-Optics designs, it is hand-assembled in small numbers and built to extract maximum compactness from a minimal element count. The aperture runs from f/6.3 to f/16 and is clickless, allowing stepless adjustment, while focusing uses a long-throw helicoid that turns about 120 degrees [3]. The lens is not rangefinder coupled; although it mounts on the Leica M bayonet, it focuses by scale and the optical path reaches down to roughly 0.6 m, well past the distance at which an M rangefinder patch can confirm focus, so the rangefinder remains usable only across part of the focusing range [1][3]. In practice many users focus it by live view on mirrorless bodies. Reviewers note that the lens covers the full 35 mm frame with a generous image circle, and that on a Hasselblad X2D with an adapter it still illuminated most of the larger 44 by 33 mm sensor with only slight vignetting [3].

Because the lens is produced in limited quantities and was, by the reviewer's account, slow to sell when new owing to its awkward 40 mm focal length and slow maximum aperture, relatively few examples circulate on the used market [3]. Miyazaki has said that the special glass needed for some of his designs is no longer manufactured, and that the Prot and the related Dagonar were planned specifically to use up stock glass on hand [3]. It is easy to confuse the Prot with its sibling, the MS-Optics Dagonar 40mm f/6.3, which shares the same focal length, aperture and 47 to 50 gram class but uses a six-element Dagor-type formula and a slightly longer barrel [3].

Optical qualities

Rendering With only four elements, the Historio Prot delivers clean, sharp central rendering, and its slow f/6.3 aperture keeps the wide-open image stable across the frame, though the simple construction limits edge performance [3]. Documented behavior is otherwise modest in scope.

Flare resistance In backlit conditions the lens shows noticeable ghosting and flare, with a corresponding drop in contrast, a trait consistent with its minimal coated-element design [3].

Distortion and vignetting Distortion is very low, measured at about +0.2 percent by one reviewer, and vignetting on full-frame digital is mild [3].

Collector and user notes Edge resolution is limited by the simple formula, and on digital bodies the small effective aperture makes sensor dust more visible, so a clean sensor is advisable [3].

History

Development and Launch The lens was announced in 2017 by Sadayasu Miyazaki of MS-Optics (Miyazaki Optical) as a Leica M-mount design based on the Protar formula, with four elements in two groups, a weight near 47 grams, a minimum focusing distance around 60 cm, and an introductory price of roughly 700 US dollars [1]. In 2018 Miyazaki published a roadmap formally placing the Prot as the opening lens of the History Series and listing later homage designs to follow, including a Dagor, an Ernostar and a Petzval [2].

Special editions No widely documented military, export or major factory special variants of the Historio Prot are recorded; the lens is offered chiefly in a black finish, with chrome examples also appearing in dealer listings [3].

Collector Notes Published figures for this lens vary slightly between sources: an early announcement and one review cite a minimum focusing distance of about 0.3 m and a barrel length near 22 mm, while other listed specifications give a 0.6 m minimum distance and a shorter barrel, a discrepancy buyers should verify against the actual lens [1][3]. Prospective buyers should also confirm they are not mistaking the four-element Prot for the six-element Dagonar, as the two are externally similar [3].