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STM lenses and older EOS bodies

Started Aug 31, 2014 | Questions thread
msowsun
msowsun Contributing Member • Posts: 740
Re: STM lenses and older EOS bodies

quiquae wrote:

totleytom wrote:

I'm not sure there is a new protocol. That was always touted as one of the great advantages of the EOS system, right from the start in 1987: the camera would issue a high-level instruction, e.g. 'change focus to a nearer focus point' or 'close the aperture diaphragm', and it would be the lens which would convert that into specific instructions appropriate to the technology in the lens. We've had lenses with micro-motors (e.g. as in the 50mm f1.8), several variants of ultra-sonic motors, and now STM lenses, and (subject to the EF/EF-S/EF-M differences) they all just work on whatever body.

Well, the STM lenses do have one backwards-incompatible wrinkle: continuous AF when shooting video works only on recent APS-C cameras (650D, 700D, 100D, 70D). I did not bother to mention this before because the 350D doesn't shoot video at all.

Just to add.....

STM lenses are "optimized" for Continuous AF in that they have smoother and generally silent AF BUT.... Continuous AF during video is a function of the camera body and has NOTHING to do with the lens.

You don't need STM to do Continuous AF, and older non-STM lenses will still do Continuous AF when mounted on the appropriate body. They will just be noisy and jumpy.

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