A99 & Lens Firmware

Started Sep 21, 2012 | Discussions thread
rtrski Contributing Member • Posts: 822
Re: A99 & Lens Firmware

This still doesn't make sense to me, entirely.

I mean, yes, lenses have firmware. But I thought that was mostly a) to identify itself and provide any necessary info to the camera like motor drive voltages, reporting aperture and focal length, etc, and b) for its own internal control.

I really thought autofocusing was a matter of the camera instructing the lens "move x/y from your present focal point" where x is the relative amount it needs to move (plus or minus) and 'y' is the lenses total focal range from nearest point to infinity. Since the PDAF module is on-camera, I assumed those calculations were done on-camera, and whether the origination of the instruction is from the PDAF module or some new on-sensor PDAF points, the communication protocol would be the same. That's the whole point - the A99 is supposedly just using the dual systems to better instruct the lens to get to the right focal plane, faster, not to pass more data (e.g. instructions from two different systems, simultaneously).

This would still explain why only some lenses work to begin with because the on-sensor PDAF points need 'calibration' so to speak for a given lens's behavior so the camera can perform those calculations right and provide the right instruction.

Maybe more of the computation of "x" is done on-lens than I think.
budding (translation: currently incompetent) underwater photographer wannabe

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