Getting Better Focus With Two Subjects

Discussion in 'Digital Photography' started by downingp, Feb 2, 2011.

  1. downingp macrumors 6502a

    Joined:
    Jun 26, 2006
    #1
    I mainly take pictures/portraits of my two boys. I am using a canon 40D with a 50 mm f/1.4 primarily as well as a 28-135mm. The problem I sometimes have is getting both boys in focus when using aperture priority? Where is the best place to place the focus for them to both be sharp and in focus? Is it primarily dependent on the aperture setting? What if I want a narrow DOF (f/1.8-2.2). Is it possible to get the boys in focus and still create nice bokeh?

    Thanks in advance for comments and suggestions.
     
  2. TWLreal macrumors 6502

    Joined:
    Jul 9, 2006
    #2
    Position yourself or them so they are both on the same parallel plane of focus you are focusing on. Problem solved.
     
  3. downingp thread starter macrumors 6502a

    Joined:
    Jun 26, 2006
    #3
    Does it matter which of the boys I put the focus on as long as they are in the same plane?
     
  4. TWLreal macrumors 6502

    Joined:
    Jul 9, 2006
    #4
    No, if they are on a parallel plane as your focusing point is, everything on that plane will be in focus. Plus and minus some distance from your plane of focus that gives you your depth-of-field.
     
  5. cleanup macrumors 68030

    cleanup

    Joined:
    Jun 26, 2005
    Location:
    Toronto
    #5
    I've found that at f/1.8 and closer distances (on my 35mm), DOF can be so thin that a face might start to lose focus as early as the edges of the eyes/between the eyes and the ears. If you can't seem to get everything you want in focus, try moving further away from your sons. And there's nothing wrong with stopping down just a bit. You'll still get pleasing bokeh, but a deeper focus plane.
     
  6. jabbott macrumors 6502

    Joined:
    Nov 23, 2009
    #6
    Here is an online depth of field calculator that you can use to determine how much will be in focus, given a certain camera body, lens focal length, aperture and subject distance. The 50mm f/1.4 you are using has a razor thin depth of field, so at 3.6 feet distance your subject(s) will only have 1 inch front to back that is in focus. The comments above about keeping both people in the same plane are certainly pertinent, but at f/1.4 at close range, even the breathing of a person (you or the subject(s)!) can cause the subject(s) to quickly move in or out of focus. To avoid that, you have a few options:
    • Take shots immediately after getting auto focus confirmation to reduce the odds that camera or subject movement have happened
    • Use a narrower aperture / larger f-number
    • Increase your camera to subject distance
    • Use a lens with a smaller focal length (e.g. switching to a 35mm f/1.4 doubles your depth of field at the same aperture)
    • Use a full-frame or larger format camera (e.g. the 5D Mark II provides 1.6x the depth of field of a 40D using the same lens/aperture/subject distance)
    Each of these has trade-offs, so you must decide what works best for you and the scenario you are in.
     
  7. Xander562 macrumors 68000

    Xander562

    Joined:
    Apr 2, 2006
    #7
    Something no one has mentioned: always focus on the eyes. Humans automatically look at the eyes of whatever subject is being photographed, so they are the most important feature to get in focus. Put your AF to single point, and when you're taking the picture put this point on their eye. Then, once the camera has focused, move and re-frame the picture how you like before you press the shutter completely. Blam-o an in focus picture.
     
  8. Ruahrc macrumors 65816

    Joined:
    Jun 9, 2009
    #8
    Also, if you find you need to stop down in order to get more DoF, you can increase "background bokeh" by putting more separation between your subjects and the background.
     

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