Fujifilm X-Mount vs. M42 Screw Mount
Comparing 2 standards across 12 specifications. 12 key differences identified.
The Fujifilm X-Mount (introduced in 2012 for the X-Pro1) is a dedicated APS-C mirrorless bayonet mount featuring a 17.7 mm Flange Focal Distance, a 40.7 mm throat diameter, and a 10-pin electronic interface. Designed exclusively for APS-C image circles, it allows compact lens designs optimized for Fujifilm's proprietary X-Trans CMOS sensors.
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.
Specification Comparison Table
12 Parameters| Parameter / Spec | ||
|---|---|---|
|
Flange Focal Distance (FFD)
|
17.70 mm (0.697 in) | 45.50 mm (1.791 in) |
|
Inner Throat Diameter
|
40.70 mm (1.602 in) | — |
|
Back Focus Distance
|
Minimum rear optical element clearance of 7.5 mm from sensor | — |
|
Bayonet Tabs
|
3 locking tabs with counter-clockwise mount twist | — |
|
Electronic Interface
|
10 contact pins (opened to third parties in 2020: Tamron, Sigma, Voigtländer, Viltrox) | — |
|
Physical Aperture Rings
|
Standard mechanical aperture rings with 1/3-stop clicks on XF lenses | — |
|
Camera Systems
|
Fujifilm X-T5, X-H2, X-H2S, X-T30 II, X-S20, X-Pro3, X-E4 | — |
|
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 |