Image sensor P-AF technology spreading...

Discussion in 'Digital Cameras' started by Alfred Molon, Aug 30, 2012.

  1. Alfred Molon

    Alfred Molon Guest

    .... and not good enough yet.

    Sony has added it to its new NEX 5R camera, but apparently the
    technology is still not good enough for accurate focus (needs to be used
    together with C-AF). I wonder if sensor P-AF will ever be able to
    replace the dedicated P-AF system of DSLRs or if the future will be
    cameras using image sensor P-AF in combination with C-AF.
    Alfred Molon, Aug 30, 2012
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  2. I've waited for just such a claim to pounce on ...
    OK, you talk about on-sensor PDAF, I don't ... though I don't
    think it makes much difference at all.

    [Canon AF]
    Well, whatdaya expect ... PDAF can be just as accurate than
    CDAF or manual focus w/live view. It just isn't every time!
    It can result in slightly soft photos.
    That's the crux.
    And you need to adjust the microfocus if needed.
    Triggering the AF multiple times doesn't help.
    Comparing the oldest lens model (1988) versus the newest new
    lens model (2012) (both 24mm f/2.8) shows that the newer lens
    is better to focus in life view and manual focus on a 5DII (PDAF
    is unaffected).
    Hmmm, what's happening when the 5DIII is paired with the
    new 24mm lens? Odd ... Really Odd ... maybe it's just the
    centre AF point?
    Oh, and it's the same with the 5DIII and the new 28mm lens!
    Things being strange and unexpected ... let's check a number
    of recent lenses (several copies on several copies of
    bodies). Hmmm ... the 2010 70-300mm too, but not the 2010
    70-200mm. Though it *is* better than older lenses ...
    So let's test camera bodies on the 28mm lens with the strange
    results. Short answer: The big sensor cameras have been steadily
    improving (except the 5DII, which has a consumer AF) with the 1DIV
    pretty good and the 1Dx and 5DIII sharing the top spot (and the
    same strange result), the 650D (T4i) with it's hybrid AF IS the
    best of the consumer crowd, but in absolute terms only as good
    as the really old 1DIII.

    Oh, and for the grand finale: confirmation of the findings in
    published literature and a 2003 patent. PDAF can be just as
    accurate as CDAF, every time, any time --- and still be blazingly
    fast. You may need to tune the microfocus adjustment though.
    And you need new cameras with AF sensors sensitive enough to use
    it and new lenses accurate enough to archive it. I guess making
    on-sensor PD sensors sensitive enough is just engineering now.

    Wolfgang Weisselberg, Sep 2, 2012
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