Pekka Buttler, 02/2024
Specifications
The table below summarizes the lens’ key specifications (measurements based on pictured sample):
| Brand: | Helios | Lens name | 81H MC |
| Focal length(s)1 | 50 mm | Angle-of-view2 | 45 ° |
| Maximum Aperture | f/2 | In Production | 1965-1997 |
| Lens mount | Nikon F | Other available lens mounts | M42, Kiev Automat |
| Length3 | 30,7 mm | Diameter4 | 62,3 mm |
| Filter ring diameter | 52 mm | Weight | 213 grams |
| Lens element count | 6 | Lens group count | 4 |
| Aperture blades (S/R/C)5 | 6 S | Focus throw | 270 ° |
| Minimum focusing distance | 50 cms | Maximum magnification | 1:7,9 |
| Has manual aperture ring | YES | Has Manual focus ring | YES |
Further technical notes:
• The lens’ angle-of-view is reported as 45 °, which would be a bit wider than that of typical 50 mm lenses (on full-frame). However, as somewhat typical for Soviet standard lenses, the lens’ focal length is sometimes reported as 50 m and sometimes (more rarely) reported as 53 mm. As I do not have the apparatus to verify the field of view, I will have to base my information on sources that are traditionally valid.
• Having a length that is less than half of its diameter, this lens technically qualifies as a pancake lens.
• The four versions of this lens are:
• Helios-81 AUTOMAT (Kiev Automat mount)
• Helios-81H (Nikon F mount – H is N in cyrillic)
• Helios-81M (M42 mount)
• Arsat-H 50 mm f/2 (Ukranian/post-Soviet version of the 81H)
Historical notes on the Helios-81N
• The earliest samples of the Helios-81 design were intended to be used as standard lenses on the Kiev Automat system (Kiev 10 and Kiev 15 cameras). Read more of that system here.
• Subsequently, the lens was somewhat redesigned (more compact housing) and offered as a entry-level standard lens on the Kiev 17/19 SLR system that used a Nikon F mount (more info on that episode here). All Nikon mount versions of the Helios-81 are Ai-compatible.
• Both these lenses were manufactured at the Arsenal plant in Kiev. There’s also a rarer model (Helios-81M) manufactured by KMZ for the M42 mount.
• The name ‘Helios’ is not a brand, nor a manufacturing organisation. Instead, the name Helios was originally used in the Soviet union to denote various Carl Zeiss Jena Biotar remakes, but was later repurposed simply as a catch-all name for double-Gauss typed fast standard lenses. The Soviet logic was different, and in very many ways. Read more here.
• The Helios-81 for the Kiev Automat was manufactured starting in 1965; while the Nikon F mount version went into production in the late 70s. All samples of the M42 mount version I have seen hail from the early 1980s.
• After the Fall of the Soviet Union, the Nikon F mount version of this lens remained in production under the name “Arsat-H 50 mm f/2”. The last copies I have encountered were manufactured in 1997.
A brief genealogy of Nikon SLR lens types
The type of the Nikon F lens mount used by this lens is of the ‘Ai’ (automatic indexing) subtype. A more detailed account is available here, but the development of Nikon’s SLR lenses can be briefly traced as follows:
• 1959–1977: Pre-Ai. Manual focus lenses that use ‘rabbit ears’ to communicate selected aperture with the camera body.
• 1977–1986: Ai and Ai-s. Manual focus lenses that may have ‘rabbit ears’ for backward compatibility, but are designed to communicate selected aperture with the camera body through indentations in base of aperture control ring.
• 1986–today: AF and AF-D. Autofocus lenses that do not have a focusing motor within the lens, but rely on the focus motor within the camera. All AF and AF-D lenses are simultaneously Ai-s lenses (they are Ai-s lenses extended with AF) 6
• 1996–today AF-S and AF-P. Autofocus lenses that have an internal focusing motor and do not rely on the body having a focusing motor.
Adapting
Besides adapting, this lens can be used natively on all current high-end Nikon dSLRs and several earlier medium-to-high-end older Nikon dSLRs7. Likewise, if it still has its rabbit ears, it can be natively used on all Nikon F-mount film cameras ever produced (without the rabbit ears, it is limited to post 1977 bodies).
Thanks to being a fully manual lens (manual aperture, manual focus), the lens can be adapted to all mirrorless cameras using a suitable dumb adapter (and such adapters are easy to find). Moreover, a large range of special adapters (helicoid adapters, tilt/shift adapters, speed boosters) for using Nikon F lenses on most mirrorless systems are available.
Using Nikon F lenses on non-Nikon SLRs and dSLRs is likewise a distinct possibility. Thanks to the relatively generous flange focal distance of the Nikon F mount (46,5 mm), adapter rings for all dSLR mounts are available as well as for a goodly portion of film-era SLR mounts. Such rings may not allow for auto aperture, but even then the lenses can be used in stop-down metering mode.
Footnotes
1 Focal length is (unless stated otherwise) given in absolute terms, and not in Full-frame equivalent. For an understanding of whether the lens is wide/tele, see ‘Angle-of-view’.
2 Picture angle is given in degrees and concerns the diagonal picture angle. Rule of thumb:
> 90 ° ==> Ultra-wide-angle
70–90 ° ==> Wide-angle
50–70 ° ==> Moderate wide-angle
40–50 ° ==> ‘Standard’ or ‘normal’ lens
20–40 ° ==> Short tele lens
10-20 ° ==> Tele lens
5-10 ° ==> Long tele lens
< 5 ° ==> Ultra-tele lens
3 Length is given from the mount flange to the front of lens at infinity.
4 Diameter excludes protrusions such as rabbit ears or stop-down levers.
5 S=straight; R=rounded; C=(almost)circular at all apertures.
6 There is a further sub-class of AF-D lenses called AF-I lenses that are otherwise AF-D lenses (meaning, fully Ai-s compatible), but have an internal focus motor. Only long tele lenses were made in AF-I variants.
7 As of this writing, the following Nikon dSLRs fully support Aperture priority and manual metered modes on Nikkor Ai lenses: D2, D3, D4, D5, D6, D200, D300, D300s, D500, D600, D610, D700, D750, D780, D800, D800E, D810, D850, D7000, D7100, D7200