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Thread: A99 doubt

  1. #1
    Senior Member Rawfa's Avatar
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    Nov 2008
    Rio de Janeiro
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    A99 doubt

    Hi guys,

    I've been testing the A99 on video mode and I can only use full manual control when I set the focus to manual. Is this correct? I can't use AF while using full manual control??

  2. #2
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    Dec 2007
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    Re: A99 doubt


    "The awesomeness of the Sony A99's always-on phase-detect focusing unfortunately exacts a price when it comes to exposure flexibility. Phase-detect focusing requires a relatively large aperture to work its magic, which means that video-mode AF on the A99 just won't happen at small apertures. As a result, you can only use Aperture-Priority, Shutter-Priority, and Manual exposure modes when the A99 is set to manual focus. In the case of the Sony A99, the minimum aperture for many lenses is f/5.6, but if the lens in question has a maximum aperture greater than f/4, the minimum aperture becomes f/3.5.
    One consequence is that you can't use small apertures to get slower shutter speeds in bright lighting, if you want to use autofocus. This can produce rather choppy-looking video, as you can see below in our daytime clips of Charlotte chasing the Frisbee. For the smoothest-looking video, you'll want to keep your shutter speed no more than half the frame rate, for instance 1/60 when shooting at 30fps, 1/120 when shooting at 60fps, etc.
    The solution to too-fast shutter speeds is pretty simple: Just buy a set of ND filters to fit your lenses. You could probably get away with just an ND 0.9, which cuts the light by three stops, but for best results, you'll want a full set of 0.3, 0.6, and 0.9. This is by no means a fatal flaw for the A99; the glacially-slow AF of most SLRs using contrast-detect focusing is only useful for relatively static subjects:: Most pros "pull focus" manually, anyway. Still, it's a limitation you should be aware of and have a plan for dealing with."



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