M42 Screw Mount vs. Sony E-Mount
Comparing 2 standards across 12 specifications. 12 key differences identified.
The M42 Screw Mount (also known as the Universal Screw Mount or Praktica/Pentax Thread, standardized under DIN 4503) is a standardized metric threaded lens interface featuring an M42 × 1.0 mm thread pitch and a 45.5 mm Flange Focal Distance. Popularized by Asahi Pentax Spotmatic and Soviet Helios-44 lenses, it is the most adapted vintage manual lens standard in mirrorless photography.
The Sony E-Mount (introduced in 2010 for NEX mirrorless and expanded in 2013 to 35mm full frame as FE) is a 3-tab bayonet lens mount featuring a 18.0 mm Flange Focal Distance (FFD), a 46.1 mm throat diameter, and a 10-pin high-speed electronic interface. It is the most widely adopted open third-party full-frame mirrorless mount in the photographic industry.
Specification Comparison Table
12 Parameters| Parameter / Spec | ||
|---|---|---|
|
Flange Focal Distance (FFD)
|
45.50 mm (1.791 in) | 18.00 mm (0.709 in — distance from lens mount mating surface to sensor plane) |
|
Thread Dimensions
|
M42 × 1.0 mm metric thread (42.0 mm diameter with 1.0 mm thread pitch) | — |
|
Mounting Style
|
Direct screw-in thread (approx. 2 to 3 full revolutions to seat against flange) | — |
|
Aperture Pin Mechanism
|
Center spring-loaded pin pressed by camera stop-down lever to close iris during exposure | — |
|
Benchmark Cameras & Lenses
|
Pentax Spotmatic (Super-Takumar / SMC Takumar), Praktica L-series, Zenit-E (Helios-44-2 58mm f/2), Carl Zeiss Jena | — |
|
Mirrorless Adaptability
|
Adapted seamlessly to Sony E, Canon RF, Nikon Z, L-mount, Fuji X, and MFT via inexpensive passive aluminum rings | — |
|
Inner Throat Diameter
|
— | 46.1 mm (1.815 in) |
|
Bayonet Tabs
|
— | 3 asymmetrical locking tabs with clockwise twist lock |
|
Electronic Interface
|
— | 10 gold-plated leaf contact pins (supports real-time eye-AF tracking, OSS, active lens breathing compensation) |
|
Full-Frame vs APS-C
|
— | FE lenses cover 36×24 mm full frame; E lenses cover APS-C (auto-crops on full-frame bodies) |
|
Third-Party Protocol License
|
— | Open disclosure to lens manufacturers (Sigma, Tamron, Zeiss, Samyang, Voigtländer) |
|
Camera Systems
|
— | Sony A7 / A9 / A1 series, FX3 / FX6 cinema lines, A6000-series APS-C bodies |