RX 100 Auto-focus Issues...

Discussion in 'Sony RX100 Forum' started by Baci, Sep 21, 2012.

  1. Baci

    Baci New to SC

    Sep 21, 2012
    Is it just me...? I have this camera with me almost always, and with a couple of young kids I often find myself, when the light is right, firing off a few frames of the kids. Even with face recognition set to "on" and the square overlaid on the face of the subject turning green, I get images where the kids' low contrast faces are not in focus, while some parts of their higher contrast clothing (zippers and the like) are razor sharp. At first I thought maybe I was shooting at too low a shutter speed and the kids were moving their heads enough to blur but today outside in good light the same thing happened. I'm not a fan of the manual focus option (not on this camera at least). I'm wondering if anyone else has had this problem consistently?

    Note some of the images are in focus - one in three to five, I guess.

    Thanks for reading!
  2. bartjeej

    bartjeej SC Hall of Famer Subscribing Member

    Nov 12, 2010
    Is this happening when they're moving? In that case it might be that they moved since you focused, which combined with shallow depth of field could explain your issue.
    Welcome to Serious Compacts, by the way :smile:
  3. Baci

    Baci New to SC

    Sep 21, 2012
    An excellent point! I'll keep this in mind - might use bigger depth of field and see how that changes things. I appreciate you coming back to me bartjeej, and thanks for the welcome!
  4. mm1

    mm1 New to SC

    Sep 20, 2012
    Bratislava, Slovakia
    This page calculates depth of field and hyperfocal distance, it might be of help (DSC-RX100 is on the camera list):
    Online Depth of Field Calculator

    E.g with 28mm, f1.8 and a 2 meter distance from the subject you get a DoF of 20 centimeters (might be too shallow for you).
    Using f5.6 in the same scenario extends DoF to 64 centimeters, but you are going to need more light or a higher ISO of course.
  5. Luke

    Luke Super Moderator Subscribing Member

    Nov 11, 2011
    Milwaukee, WI USA
    mm1 raises a great point. Good thing that Sony excels in high ISO. I would suggest that anytime you're shooting kids you should be up around f5.6 just to be safe, but you need to make sure you keep your shutter speed up as well unless you want some motion blur for artistic reasons.

    ALso, welcome!
  6. Baci

    Baci New to SC

    Sep 21, 2012
    Thanks mm1 - I had not seen the Depth of Field calculator before and it has really put the tolerances involved with shooting wide open into perspective. Through force of habit I've been shooting with ISO as low as possible (usually 200, sometimes 400) but I might kick that up a notch. Early on I did some test shots at 800 and there was more noise than I was expecting to see, but that was at high magnification and can be dealt with in Lightroom anyway. Thanks all for the welcome and the information - much appreciated!