The WRE-CA links Canon EF lenses to Cambo WRS and Phase One XT technical cameras. The aperture is set at the adapter. Unlike lenses designed for view camera use, the Canon lenses don't have  built-in leaf shutters. Therefore the use is limited to digital backs that have on-sensor shutters, like the current Hasselblad CFV and Phase one IQ3 and IQ4 backs.

In general only the Canon T/S lenses have a large enough image circle to be of interest for use with a digital back.