The MTF Services Ltd. MTF EFFECT Canon EF Control Unit is a complement to a set of three separately-sold EF-mount lens adapters developed by MTF. Both the adapters and the Control Unit are a pioneering result of a long time of research and discovery. Together they let you control the aperture of a Canon EF-mount lens on a non-Canon, non-EF camera. They moreover let you open up aperture at much more accurate f-stop increments of 1/8, whereas even on Canon cameras aperture opens in increments of 1/3 only. Furthermore, both of the above factors are achievable even on EF lenses that have image stabilization. All of this has never been possible before, and it allows you to use your Canon lenses without aperture restrictions on non-Canon, non-EF cameras.
(The Control Unit has successfully been tested with all Canon and Zeiss EF lenses, and successfully with most third party EF lenses, but may not work with -- it may not succeed in controlling the aperture of -- some third-party EF lenses.)
Previous to this innovation, using an EF lens on a non-EF camera by means of an EF adapter meant that you'd be stuck with the aperture that was already set on the lens, and that the only way to change the aperture would be by dismounting the lens, attaching it to a Canon camera, adjusting the aperture to what you want it at, and then remounting the lens back onto the non-EF camera, and all over again for every adjustment. This is so because Canon lenses have no manual aperture control and are purely electronic, and because a regular EF adapter only lets you mount an EF lens but isn't capable of transferring any electronic information.
The adapters that this Control Unit works with though are a bit different than regular EF adapters. Each features an integrated cable for use with the Control Unit. The cable plugs into the Control Unit and enables lens control, and the Control Unit has a knob that adjusts aperture (and a display that indicates aperture as well as focal length). The adapters available are an EF to Sony E, an EF to Sony F3, and the third an EF to Micro 4/3.
The Control Unit is meant to be kept close to the camera and lens, and it features three 1/4" screw-holes, spread out among its sides, to be mounted by. A most ideal way of mounting it is by a Noga Arm. As for power, the Control Unit works off of four AA batteries, which are enough for a full day of shooting. The batteries are not included. The Unit is designed and built in England.