Camera mount adapter / BackfocusLab

Sony/Minolta A to Sony E adapter thickness

A glassless Sony/Minolta A to Sony E adapter must be about 26.5 mm thick to keep a Sony/Minolta A lens focusing correctly on a Sony E body. This equals the Sony/Minolta A flange focal distance minus the Sony E flange focal distance, both published mount-design constants, reviewed 2026-09-12.

How this is computed

Using the Sony/Minolta A flange-to-sensor distance as a one-component train against a backfocus target equal to the Sony E flange focal distance (filter correction off), BackfocusLab's own model reports the spacing gap between them as the required adapter thickness.

Source mount (lens side)
Sony/Minolta A, 44.5 mm FFD
Target mount (body side)
Sony E, 18 mm FFD
Adapter thickness
26.5 mm

This is illustrative arithmetic, not a substitute for the manufacturer's own adapter specification; small machining tolerances exist. A dumb, glassless adapter only forwards the mechanical mount; it makes no claim about autofocus, aperture control, or electronic contacts, and a nominal fit is not a compatibility guarantee. Verify against your camera manufacturer's published specification before ordering.

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