Lens adapter compatibility

Pentax K lenses on Canon RF cameras

Can you use Pentax K lenses on Canon RF cameras? Yes, with a simple mechanical adapter (manual focus). The Pentax K flange distance is 45.46 mm and Canon RF is 20.00 mm, a difference of +25.46 mm.

+25.46 mm

Space for the adapter

45.46 mm

Pentax K flange

20.00 mm

Canon RF flange

Verdict: Yes — a simple 25.5 mm adapter keeps infinity focus.

What to expect#

Aperture control: lenses with a manual aperture ring work directly; electronically controlled lenses (no ring) need a smart adapter or one with a built-in aperture lever.

Focus: use focus peaking and magnification in the viewfinder. Exposure metering works normally because the camera meters through the lens at working aperture.

Pentax K lenses you could adapt#

Canon RF cameras#

Other systems for Pentax K lenses#

Sony E-mount Nikon Z Fujifilm X-mount Micro Four Thirds L-Mount Canon EF-M Fujifilm G-mount Hasselblad XCD Nikon 1 (CX)Pentax Q

Frequently asked questions#

Will Pentax K lenses autofocus on Canon RF?

No — adapted lenses are manual focus on this combination.

Does a Pentax K to Canon RF adapter affect image quality?

A glass-free adapter is just a precisely machined spacer, so image quality is unchanged when it is built to the right thickness. Cheap adapters can be slightly too thin or thick, which shifts the infinity mark.

Last updated October 03, 2026 · How we calculate · Sources