Archived posting to the Leica Users Group, 2014/02/22

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Subject: [Leica] OT - Sony Alpha 7R
From: wildlightphoto at (Doug Herr)
Date: Sat, 22 Feb 2014 08:52:43 -0800 (GMT-08:00)

Frank Filippone wrote:

( why there really is a
fine focus adjust feature in higher end cameras.. camera AF is adjusted by
the user to nail down the precise focus location. 

AF micro-adjust is on DSLR cameras so that the user can compensate for the 
differences between the image plane at the AF sensor and at the image 
sensor, and for differences in the phase-detect system's assumption of the 
lens' focal length and the actual focal length (read: manufacturing 
tolerances).  A camera using the image sensor as the AF sensor eliminates 
the image plane discrepancy and a phase-detect + contrast-detect system such 
as used by the A7 eliminates the phase-detect system's focal length 
assumption discrepancy.  The A7 (and A6000) should have no need for AF 
micro-adjustment, likewise the A7r which is contrast-detect only.

Doug Herr
Birdman of Sacramento

Replies: Reply from photo at (Nathan Wajsman) ([Leica] OT - Sony Alpha 7R)