(SR5) UPDATE -> New Sony patent shows a new lens

“The patent does not relate to simply making a 16-80mm f/2.8-3.5 – it relates to how the problem of keeping lens size down is tackled. The patent covers the concept of moving the position of aperture at ONE exact point in the zooming, so the lens has two apertures. From 16 to 24mm, it is a constant f/2.8 – from 25mm to 80mm, it is a constant f/3.5. Instead of the gradual change (reported by the lens IC as a series of 1/3rd or 1/2 stop steps, according to how your camera is set) this lens is like having two constant aperture zooms.

One of the problems currently being faced by Canon is their inability to use electronic aperture zooms, with variable apertures, for smooth changes in exposure during video filming. Unlike the mechanical aperture of the Alpha mount, which is analog in operation though the camera limits it to fixed settings, the Canon EF aperture is electronically set in 1/3rd steps and can not be varied smoothly. Constant aperture zooms are vital for video, and ISO variation is the preferred way to cope with light changes during video.

Sony’s patent may be partly connected with perfect smooth control (continuous) of aperture, which will be necessary to make the Alpha system match their exacting video standards. It could be accompanied by a zoom range limiter, to ensure that the user does not zoom through the sudden position-shift of the iris assembly within the lens described in the patent.

The benefits of using a variable position aperture (or in this case, a two-position aperture) are seen in a substantial reduction of the diameter and size required for the front zoom group – a negative group, like a retrofocus w/a – without aberration and vignetting issues.”