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Old 23rd June 2017
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Ross the fiddler Ross the fiddler is offline
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Re: AF Fine Adjustment on E-M1 Mk II

Originally Posted by DerekW View Post
I do not understand why a fine adjustment has to be made on a mirrorless camera as the focus sensors are on the same plane as the image sensor (actually part of the image sensor), I can understand why on a dSLR as the focussing device is away from the film plane.
If the camera is using PD-AF it instructs the lens to focus at a particular setting according to the detected phase angle (or whatever it is detecting), & that may not necessarily be exactly in focus at the intended critical point because the lens may not be as accurately calibrated for PD-AF, so a fine adjustment stored in the camera can correct that. The difference here is understanding how the PD-AF is combined with CD-AF & when. I think that 'touch' AF (using magnification method) only uses CD-AF & may get around occasions where (PD-)AF can have anomalies.
I fiddle with violins (when I'm not fiddling with a camera).
Cameras: OM-D E-M1 & Mk II, Olympus Stylus 1, OM-D E-M5.
Lenses: M.ZD7-14mm f2.8 PRO Lens, M.ZD12-40mm f2.8 PRO Lens, M.ZD40-150mm f2.8 PRO Lens, MC-14, MC-20, M.ZD45mm f1.8, M.ZD12-50, M.ZD60 Macro, M.ZD75-300 Mk II, MMF-3, ZD14-54 II, Sigma 150mm F2.8 APO Macro DG HSM.
Flashes: FL36R X2, FL50R, FL50.
Software: Capture One Pro 10 (& Olympus Viewer 3).
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