I am selling my mint condition Optitek ProLock Mark II. I used it about a dozen times on a F5 with various Canon EF lenses. This is a great option for using more the affordable Canon DSLR lenses on the F3/F5/F55. The KEY feature of the Mark II is that it is powered by the mount so so power cable is required.
New was $1800, asking $1400. Make an offer!
Pictures emailed upon request
The Prolock EF has electrical contacts to allow powered control over the iris in 1/3 stop increments via keys on the mount. The mount adapter also provides power to IS stabilization and internal focus servos. When used with the Optitek Optitron Lens Controller, precision repeatable remote focus control is also available. The Optitek Prolock EF draws its power directly from the camera mount, so no additional cable is required. The Optitek Prolock EF also features a PL-style clamping lock ring on the Canon EF mount, assuring that the lens will not shift in the lens mount.