What the standard defines
Nothing shared, and that is the point of this page. A mount is a bayonet — a flange, a set of lugs, a locking pin and an arrangement of electrical contacts — designed by a camera maker for its own bodies and published in that maker’s own documentation. Eight designations appear in this catalogue’s titles, each belonging to one owner.
Behind the bayonet sits the figure that decides what can be adapted: the flange distance, the gap between the mounting face and the sensor. Each maker publishes it for its own system, and the comparison between two of those figures is the whole of adapter compatibility.
What it does not promise
No cross-compatibility. Two mounts of similar diameter are not interchangeable. Sharing a diameter says nothing about lugs, lock position, contact placement or flange distance.
No adapter in both directions. An adapter is a spacer with a fitting at each end. It can only add distance, so it works when the lens was built for a longer flange distance than the body expects. In the other direction, focus at infinity is lost, and no thickness of adapter recovers it — this is arithmetic, not a limitation of manufacture.
No electrical function. Contacts differ between systems. What an adapter passes — aperture control, autofocus, stabilisation signalling, lens data — is a property of that adapter, published by whoever made it, and absent from most listings.
No image circle. A mount fits or does not. Whether the lens covers the whole of the sensor behind it is separate, published per lens, and the figure that decides whether a lens built for a smaller format will fill a larger frame.
What it works with
Every lens and every adapter in this catalogue, and the teleconverters that sit between the two — those carry their own optics and multiply the focal length, which is a different operation from spacing a lens back to its designed distance. For filters, the figure that matters is the thread diameter on the front of the lens, which has nothing to do with the mount behind it.
What people ask before they commit
Why can a mirrorless body take almost any older lens with an adapter?
Because its flange distance is shorter. An adapter can only add distance between lens and sensor, never remove it, so a lens designed for a longer flange distance can be moved back to where it expects to sit. Where the target flange distance is the longer of the two, no adapter of any thickness can recover infinity focus — which is why the adapters in this catalogue run in one direction and not the other.
Does an adapter lose autofocus?
It depends entirely on what the adapter carries, and this is published per adapter rather than implied by the mounts. A purely mechanical adapter passes no signals at all, so aperture and focus become manual. One with contacts may pass some functions and not others, and the honest listings name which; the ones that do not name them are stating nothing, not stating everything works.
Last reviewed 12 September 2026