Data sheet: Auto Mamiya/Sekor SX 200 mm f/3.5 (M42/SX mount)

Pekka Buttler, 10/2024

Pictured: Auto Mamiya-Sekor SX 200 mm f/3.5

Specifications

The table below summarizes the lens’ key specifications (measurements based on pictured sample):

Brand:Mamiya/SekorLens nameSX 1:3.5 f=200mm
Focal length(s)1200 mmAngle-of-view212,3°
Maximum Aperturef/3.5In Production1974-1977
Lens mountMamiya M42/SXSubfamily (if applicable)––
Length3139,5 mmDiameter471,9 mm
Filter ring diameter58 mmWeight575 grams
Lens element count4Lens group count4
Aperture blades (S/R/C)58 SFocus throw290 °
Minimum focusing distance2,3 mMaximum magnification1:9,4
Has manual aperture ringYESHas Manual focus ringYES
Aperture mechanism typeAutoAperture click stops:63.5••5.6•8•11•16-22

Further notes:

• In May 1974 Mamiya introduced the MSX line (MSX500 and MSX1000) of cameras and lenses. The MSX line was quickly followed by the DSX7 line (DSX500 and DSX1000) of cameras.
• The MSX/DSX line of cameras could use the entire repertoire of M42 lenses (including Mamiya’s previous M42 lenses), but these cameras really came into their own when used with Mamiya M42/SX lenses. These lenses not only enabled locking lenses on the camera body, but communicated the selected aperture to the camera by means of a pin in the base of the aperture ring (see below). This pin – incidentally – made Mamiya M42 SX lenses incompatible with most M42 camera bodies.
• Mamiya’s lineup of M42/SX lenses was relatively comprehensive, ranging from a 14 mm fisheye to a 800mm ultra-tele lens.
• As part of that lineup were two medium telephoto lenses: one 135 mm f/2.8 lens and another 200 mm f/3.5 lens [this lens]
• The lens sports a built-in extendable lens hood, that is long enough to potentially be truly effective.

Top: Focused at infinity and with hood retracted.
Bottom: Focused at MFD and with hood extended.

Versions and related designs

Within the relatively short timespan of the Mamiya M42 SX system, I am not aware of more than one variant of the SX 200 mm f/3.5 lens having been manufactured.

The Auto Mamiya/Sekor SX 200 mm f/3.5 lens is part of a long lineage of 200 mm f/3.5 lenses from Mamiya, summarised briefly below:

NameMountDesignBladesMFDFilter thread ⌀weight
Auto 200 mm f/3.5 (I)M424 e / 4g83,0 metres67 mm750 g
Auto 200 mm f/3.5 (II)M424 e / 4g82,5 metres62 mm735 g
Auto 200 mm f/3.5 (III)M424 e / 4g82,3 metres58 mm565 g
ES Auto 200mm F/3.5ES4 e / 4g?2,3 metres58 mm960g
SX Auto 200mm F/3.5M42/SX4 e / 4g82,3 metres58 mm575 g
CS Auto 200mm F/3.5NC/CS4 e / 4g52,3 metres58 mm490 g

History of Mamiya M42/SX lenses

Please see the JAPB article on all (7) Mamiya SLR lens mounts to understand the role of the Mamiya M42/SX mount .

Adapting

n.B! The following applies to all Mamiya M42/SX mount lenses.

This lens cannot be used natively on any current SLR or dSLRs. To use it in its native environment, you will need a Mamiya MSX or DSX-series film body. While the Mamiya MSX/DSX system was quickly overtaken by events, the cameras themselves were thoughtfully designed and well-made and many remain perfectly serviceable today.

Should you aim to adapt this lens to a mirrorless camera you will need an M42 adapter that does not conflict with the aperture ring linkage pin (in the base of the aperture ring). Luckily, most M42 adapters I’ve seen does allow mounting Mamiya M42/SX lenses. The popularity of the M42 mount means that special adapters (helicoid adapters, tilt/shift adapter and speed boosters) are relatively readily available.

Using M42 lenses on dSLRs can also an easy option, but you will (again) have to find an adapter that does give room for the aperture ring linkage pin. Thereafter your level of success in adapting also depends on which dSLR you are hoping to adapt to:
• Canon EF, Minolta / Sony A and Pentax K dSLRs are able to mount M42 lenses perfectly using a simple adapter ring.
• Nikon F dSLRs have a long flange focal distance, meaning that mounting M42 lenses needs an adapter that uses corrective optics to allow anything close to infinity focus.

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 (based on manufacturers’ specs) 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. Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click. ↩︎
  7. While the MSX line offers typical TTL spot metering, the DSX offers dual metering systems, allowing the user to choose between spot metering and average metering – something Mamiya had first introduced in 1968 with the DTL line of cameras.. ↩︎

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