Optitek Canon ProLock Mark III for Sony F3, F5 and F55

Note that the electronic version of the adapter is very important, as Canon EFlenses as a rule do not have manual iris rings, so without the electronics, there would be no way to control the iris control and the lens would be always in a fully open iris mode.

Same mechanically as the Mark II but offers a few upgrades: iris initialize by either the iris up or iris down button, 1/8 stop increments for opening/closing, sequential action when the button is held down (iris up or down button).