Yes—adapter quality can matter even if you only manual focus.

The main issue is mechanical accuracy, not autofocus. An adapter sits between lens and camera, so if it is out of tolerance it can affect flange distance or tilt the lens relative to the sensor. Even very small misalignment can be visible on modern high-resolution sensors, especially as softness or uneven sharpness across the frame.

A better adapter may therefore improve consistency and alignment, but price alone does not guarantee this. A more expensive adapter with electronic pass-through or EXIF support is not automatically built to tighter tolerances than a simple manual adapter.

So if manual focus is your only concern, the real benefit of a better adapter is potentially better fit, alignment, and build quality—not autofocus features themselves.

The same logic applies whether the lens is a manual-focus lens or an autofocus-capable lens that you choose to focus manually. Manual focusing an AF lens may feel less precise because many AF lenses have shorter focus throw, but that is a lens design issue rather than an adapter advantage.