Adapter guide
M42 lenses on L-mount
Yes, this works. M42 has a 45.46mm flange distance and L-Mount Alliance (Leica, Panasonic, Sigma) has 20mm, so a 25.46mm mechanical adapter with no glass fills the gap and infinity focus is preserved. Focus and aperture stay manual.
- M42 flange
- 45.46 mm
- L-mount flange
- 20 mm
- Adapter thickness
- 25.46 mm
- Optical elements
- None required
Setting it up
On Panasonic S bodies set Shoot w/o Lens to On and enter the focal length for stabilisation. Leica SL bodies accept adapted lenses without a setting change and Leica sells its own R-Adapter L for Leica R glass.
Three aperture systems exist: preset (two rings, no pin), manual, and automatic diaphragm with a rear pin that the camera body pushes to stop down.
M42 lenses and their field of view on L-mount
Effective focal length changes with sensor size. The lens itself does not change; the smaller sensor simply captures a narrower part of the image circle.
| Lens | Focal length | Aperture | Full frame | Frames like (APS-C (1.5x)) | Years | Used value |
|---|---|---|---|---|---|---|
| Asahi Pentax Super-Multi-Coated Takumar 50mm f/1.4 | 50mm | f/1.4 | 50mm | 75mm | 1971-1975 | $70 to $240 |
| Asahi Pentax Super-Takumar 50mm f/1.4 | 50mm | f/1.4 | 50mm | 75mm | 1964-1971 | $80 to $400 |
| Asahi Pentax Super-Takumar 55mm f/1.8 | 55mm | f/1.8 | 55mm | 83mm | 1958-1971 | $35 to $130 |
| Carl Zeiss Jena Biotar 58mm f/2 | 58mm | f/2 | 58mm | 87mm | 1936-1960 | $120 to $550 |
| Carl Zeiss Jena Flektogon 20mm f/4 | 20mm | f/4 | 20mm | 30mm | 1960s-1980s | $250 to $750 |
| Carl Zeiss Jena Flektogon 35mm f/2.4 | 35mm | f/2.4 | 35mm | 53mm | 1975-1990 | $130 to $380 |
| Carl Zeiss Jena Pancolar 50mm f/1.8 | 50mm | f/1.8 | 50mm | 75mm | 1965-1980 | $70 to $260 |
| Fujinon 55mm f/1.8 EBC | 55mm | f/1.8 | 55mm | 83mm | 1972-1978 | $50 to $170 |
| Helios 40-2 85mm f/1.5 | 85mm | f/1.5 | 85mm | 128mm | 1970s-present | $90 to $350 |
| Helios 44-2 58mm f/2 | 58mm | f/2 | 58mm | 87mm | 1958-1992 | $25 to $130 |
| KMZ Industar-61 L/Z 50mm f/2.8 | 50mm | f/2.8 | 50mm | 75mm | 1970s-1990s | $25 to $100 |
| KMZ Jupiter-9 85mm f/2 | 85mm | f/2 | 85mm | 128mm | 1950s-1980s | $90 to $320 |
| KMZ Mir-1 37mm f/2.8 | 37mm | f/2.8 | 37mm | 56mm | 1954-1980s | $40 to $160 |
| Meyer-Optik Gorlitz Trioplan 100mm f/2.8 | 100mm | f/2.8 | 100mm | 150mm | 1950s-1970s | $250 to $900 |
| Pentacon auto 50mm f/1.8 | 50mm | f/1.8 | 50mm | 75mm | 1960s-1990 | $20 to $90 |
Frequently asked
Do M42 lenses work on L-mount cameras?
Yes. A plain M42 to L-mount adapter works with no optics. M42 has a 45.46mm register and L-Mount Alliance (Leica, Panasonic, Sigma) has a 20mm register, so the adapter is a 25.46mm tube that puts the lens exactly where a M42 body would. Plain threaded adapter, no optics. Lenses with an auto-diaphragm pin need either an Auto/Manual switch on the lens or an adapter with an inner flange that holds the pin in. Preset lenses such as the Helios 44-2 have no pin and work on any adapter.
Do M42 lenses focus to infinity on L-mount?
Yes. Because the adapter restores the native 45.46mm register, infinity focus is preserved and the full focus scale on the lens stays accurate. Adapters machined slightly short let the lens focus past infinity by a small margin, which is harmless; adapters machined long stop short of infinity, so buy from a maker with tight tolerances.
What focal length does a M42 lens become on L-mount?
On full frame L-mount bodies (Leica SL series, Lumix S series, Sigma fp) the focal length is unchanged: a 50mm lens frames as a 50mm. On APS-C (1.5x) L-mount bodies (Leica CL, TL, TL2) a 50mm lens frames like a 75mm lens on full frame; the aperture and depth of field at a given distance do not change.
More on this mount: M42 mount reference