Adapter guide
Pentax K lenses on MFT
Yes, this works. Pentax K has a 45.46mm flange distance and Micro Four Thirds has 19.25mm, so a 26.21mm mechanical adapter with no glass fills the gap and infinity focus is preserved. Focus and aperture stay manual.
- Pentax K flange
- 45.46 mm
- MFT flange
- 19.25 mm
- Adapter thickness
- 26.21 mm
- Optical elements
- None required
Setting it up
Enable Shoot w/o Lens (Panasonic) or leave Release Priority on (Olympus and OM System), then enter the focal length for in-body stabilisation. The 2x crop doubles the apparent focal length, so a 50mm frames like a 100mm.
Automatic diaphragm. Pentax-A and later lenses add an A position on the ring that hands aperture control to the body; leave it off A on an adapter.
Pentax K lenses and their field of view on MFT
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 | Frames like (Four Thirds (2x)) | Years | Used value |
|---|---|---|---|---|---|
| Pentax SMC Pentax 50mm f/1.2 | 50mm | f/1.2 | 100mm | 1975-1990s | $300 to $800 |
| Pentax SMC Pentax-M 50mm f/1.4 | 50mm | f/1.4 | 100mm | 1977-1984 | $60 to $210 |
Frequently asked
Do Pentax K lenses work on MFT cameras?
Yes. A plain Pentax K to MFT adapter works with no optics. Pentax K has a 45.46mm register and Micro Four Thirds has a 19.25mm register, so the adapter is a 26.21mm tube that puts the lens exactly where a Pentax K body would. Plain adapter ring. Because K keeps the 45.46mm M42 register, M42 lenses also mount on K bodies with a thin adapter and keep infinity.
Do Pentax K lenses focus to infinity on MFT?
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 Pentax K lens become on MFT?
On Four Thirds (2x) MFT bodies (Lumix G, GH, GX; OM-D and PEN; OM-1 and OM-5) a 50mm lens frames like a 100mm lens on full frame; the aperture and depth of field at a given distance do not change.
More on this mount: Pentax K mount reference