M42 Screw Mount vs. Nikon F
Comparing 2 standards across 11 specifications. 11 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 Nikon F-Mount (introduced in 1959 with the legendary Nikon F SLR) is one of the most storied lens mounts in photographic history, maintaining a continuous 46.5 mm Flange Focal Distance and 44.0 mm throat diameter for over 60 years. Spanning non-AI manual lenses to modern electronic-diaphragm AF-S/AF-E glass, over 100 million F-mount lenses were produced.
Specification Comparison Table
11 Parameters| Parameter / Spec | ||
|---|---|---|
|
Flange Focal Distance (FFD)
|
45.50 mm (1.791 in) | 46.50 mm (1.831 in — longest FFD among major 35mm SLR mounts) |
|
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
|
— | 44.00 mm (1.732 in) |
|
Bayonet Tabs
|
— | 3 locking tabs with counter-clockwise twist (opposite of Canon/Sony) |
|
Historical Generations
|
— | Non-AI (1959) -> AI (1977) -> AI-S (1981) -> AF screw-drive (1986) -> AF-D (1992) -> AF-S Silent Wave (1998) -> AF-E Electronic diaphragm (2010s) |
|
Aperture Control History
|
— | Spring-loaded mechanical stop-down lever (moved to electromagnetic diaphragm in 'E' lenses) |
|
Camera Systems
|
— | Nikon F, F3, FM2, F5 (film), Nikon D850, D780, D6, D7500, D500 (digital DSLRs) |