matthewsaville
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AGeoJO wrote:
Against popular beliefs, the aperture inside Nikon lenses is still mechanical and it is activated by a lever in the body. I am not sure whether or how adapter manufacturers can design an adapter that includes both a mechanical and electronic portions in the same unit. I am sure it could be done but at what cost? And how much of battery power will be used to achieve this? The battery charge is one of the many negative factors of the A7 series cameras...
Currently, this issue is overcome in many different lenses in many different ways.
Rokinon lenses have both a mechanical aperture lens tab, and electronic contacts that transmit focal length and aperture data, so you can have all EXIF embedded, (except maybe focus distance) and you can even control the aperture from the camera via a dial. The same goes for Pentax-mount Rokinon lenses.
Ironically, Canon-mount Rokinon lenses that have EXIF data transmitting chips are far more rare than "dumb" lenses that simply have a mechanical aperture tab, even though it shouldn't cost them any more than making a Nikon-mount version. Maybe Canon's electronic contacts simply cannot fathom the idea of mechanically controlling the aperture AND transmitting the info to the body. Bummer.
Nikon's older AI-S glass, which have no electronic contacts, simply require that you input the focal length and aperture info into the camera, and then it uses mechanics for both stopping down, and detecting what f-stop you've set on the aperture ring.
Logically, a Metabones adapter could be created that allows for mechanical stop-down of a Nikon-style aperture, and an in-body menu could interface with the Metabones adapter to somehow translate "wide open" to f/2.8, and so on and so forth.
Unfortunately, physically speaking not all Nikon apertures stop down in equal increments, mm by mm, as far as I know, so for example a Canon body that uses an adapter to connect a Nikon D or G lens, cannot figure out how to gauge the info properly.
So yeah, it's probably not entirely possible, but at least some small shred of EXIF could be added, as a slight improvement over the current situation.
Either way, it is still a con in my book, having spent so many years enjoying Nikon's system. And when Nikon does finally deliver a mirrorless system, they might just do it in a way that offers more EXIF data than Sony can, who knows. Maybe that's one of the big hurdles they're trying to overcome as we speak/type... Whether to do it like Sony, and reduce the flange distance so much that almost ANY lens can be adapted, ...or do it like Pentax did, and maintain the same flange distance as a DSLR, to be perfectly compatible with all legacy lenses...
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