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p.1 #4 · p.1 #4 · Fuji 50-140 f2.8 automatically refocus or parafocal feature ? | |
Its interesting though that it automatically refocuses, without telling it it. My 18-55 by comparison doesn't do this, but that lens also doesn't show as much change of focus when you zoom.
What I can't tell is if zooming the lens, after you've locked focus, just automatically causes the lens to refocus, OR, if there is some algorithm that shifts the focus a given amount, for a given change in focal length and given focal distance.
Reason I wonder, is that if I put the AF point on a contrasty subject, on a white wall, and then move the focus point off that subject, when I turn the zoom ring the lens still adjusts the focus so the subject is sharp, even though the AF point is no longer on the subject. If the lens was simply activating the AF system again I don't think it would find focus, because I can't otherwise focus on such a low contrast subject when testing it.
As such, it seems like some sort of automatic adjustment process the lens performs.
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