Using the same Sony E-Mount as Sony NEX mirrorless cameras, it's impressive that they've been able to fit such a large full-frame sensor into the same lens mount, and you can see below. This will also have an impact on how you use Sony E-Mount lenses with the camera, with the current Sony E-Mount lenses operating differently depending on each lens.
The camera gives the option to use the lens in crop mode, or alternatively use the full frame, but with strong vignetting. A new range of Sony FE - Full-frame E-Mount lenses has been announced to take advantage of the new cameras, which are signified by "FE" in the name, including a number of lenses developed with Carl Zeiss for optimum image quality. With the Sony Alpha 7, when using Sony NEX E-Mount lenses in crop mode, the camera takes 10 megapixel photos.