Why are focus by wire lenses not compatible with the Focus Module?

With focus by wire lenses, the movement of the focus ring is measured electronically, and then a motor moves the lenses inside. This electronic movement may lead to a delay between the focus ring and focusing.

Even when you activate manual focus, you may not get the same results when you turn your focus ring to the same specific location.

If you turn the ring too fast, electronic focus lenses may not provide the sharpness when you turn the ring at a slower pace.

For example, some of the compatible lens types are:

-Rokinon

-Samyang

-Canon USM

Non-compatible lens types are:

- Sony FE

- Canon STM