Canon Extension ring EF 12 II

An extension ring is a non-optical device that increases the distance between the lens and the film. This reduces the closest focusing distance and increases the magnification.
The EF 12 II extension ring extends the extension between lens and film by about 12 mm.
Under certain conditions, autofocus works with both extension rings, but not always. Since small changes in the focus of close-ups are possible, we recommend manual focusing.
You can use the autofocus system of the EOS cameras for focus confirmation.