Lens Adapter
A ring or unit that lets a lens designed for one mount be fitted to a body with a different one.
Measured in
mm
In depth
A simple adapter is a precisely machined spacer with no glass, preserving optical quality but usually surrendering autofocus and aperture control. Electronic adapters pass signals through and can be nearly transparent within a manufacturer's own lineage. Adapters that add glass to bridge an impossible flange distance always cost image quality.
Examples in practice
A native-brand electronic adapter runs a twenty-year-old SLR lens on a mirrorless body with full autofocus and stabilisation.