How can auto focus errors be a lens problem?

Started Dec 10, 2012 | Discussions thread
ForumParentFirstPreviousNextNext unread
Flat view
guzzibreva1
Contributing MemberPosts: 907
Like?
How can auto focus errors be a lens problem?
Dec 10, 2012

I have read user reviews about Sigma lenses having focus problems on certain cameras.   I find it hard to understand how a lens can auto focus wrong.

If the camera drives the lens until it sees a sharp image on the focus sensor, it seems to me the only real source of error can be the camera. The lens could cause a problem if the focus motor would coast after the command to stop, but then the focus error would be different depending on which direction it was focusing. It would not be limited to "front focus" or "back focus"

ForumParentFirstPreviousNextNext unread
Flat view
ForumParentFirstPreviousNextNext unread
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow