DoF - Close up with 18-55 EFS Zoom

Discussion in 'Digital Photography' started by pac-a-mac, Mar 5, 2009.

  1. pac-a-mac macrumors member

    Joined:
    Sep 1, 2006
    Location:
    The British Empire
    #1
    I have looked this up but I need guidance in simple English. I got my Canon 450D last week and have just started to play around. I previously owned a Fuji F7000 and found close-ups satisfactory...to a point...hence one of the reasons to go to DSLR. I have taken a few snaps (see image attached) but as you can see the DoF is very shallow with this lens at this distance. Is it the lens or can I adjust settings to get a wider DoF. I appreciate the bundled lens is not a great piece of glass so any recommendations will be welcome. Before using digital I had (still have actually) an Olympus OM2n and always used a prime zuiko 50mm lens for close up work and again not bad results.

    EXIF data:

    Exposure Program: Aperture-priority AE
    Exposure: 0.6
    Aperture: f/5.6
    Focal Length: 55 mm
    ISO Speed: 200
    Exposure Bias: 0 EV
    Flash: Off

    [​IMG]
     
  2. pooky macrumors 6502

    Joined:
    Jun 2, 2003
    #2
    In general, you can always adjust the settings to get a greater DOF. It looks like you were at f/5.6 for this photo, which, for that lens, is wide open (or nearly so), which is going to result in a shallow DOF. A smaller aperture (meaning a higher f/x number) will give you more DOF. Realize that this will mean you will need to keep the shutter open longer, as well. A tripod will probably be needed.

    Try setting the camera to Av mode, then set the aperture to a higher number - start with f/9 or so, then tweak from there if you don't like the results.
     
  3. bking1000 macrumors 6502a

    Joined:
    Dec 29, 2007
    #3
    DOF is driven (in this case) by two factors:

    1) sensor size and
    2) aperture

    The F700 has a small digicam sensor (1/1.7"). The 450D has a DSLR sized sensor (actually an APS-C crop sensor, but it's still something like 7X bigger than the F7000 sensor. relative sizes can be seen here: http://en.wikipedia.org/wiki/File:SensorSizes.svg). Smaller sensors have a larger DOF in their image, which leads us to...

    Aperture. Larger apertures lead to narrower depth of field, smaller apertures leads to wider DOF. For these two camera sensors, the F7000 at f/2.8 is pretty close to the same DOF as the 450D around f/8 or f/11. So, if you want more DOF, you are going to have to stop down the aperture on your 450d to around f/8-11. This means, of course, that you'll need more lighting or lower ss or higher ISO.

    (edit: pooky beat me to it)
     
  4. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #4
    For the widest DOF stop the lens down to f/16 or more. Of course then you will need more light. Solve that either by using a much longer exposure (and a very sturdy tripod) or by adding a lot of light from a flash or a powerful "hot light".

    DOF is determined by a combination of the lens' focal length, subject distance and f-stop. And your tolerance for how you define "sharp".

    If your goal is only a "web resolution" image then you can pull the camera back and crop. You'll get fewer pixels but more DOF. Not quite what you asked for but perhaps what you need. What's best depends on the final use of the image.

    try Google for "DOF calulator". Here is one:
    http://www.dofmaster.com/dofjs.html If will get an exact numeric answer to your question
     
  5. pac-a-mac thread starter macrumors member

    Joined:
    Sep 1, 2006
    Location:
    The British Empire
    #5
    Great answers guys. ChrisA, the DoP calculator is an excellent way to a get a feel for depth at close range. I will be trying again with a smaller aperture setting. Looks like f11 will give me ~+/-0.5" depth from the focal point. My setting gave me ~+/-0.1". I did use a tripod but my ignorance of the camera settings for the job made let me down. Thanks again:cool:
     
  6. pac-a-mac thread starter macrumors member

    Joined:
    Sep 1, 2006
    Location:
    The British Empire
    #6
    OK this is HDR manipulated but I think I have cracked the DoP

    [​IMG]
     

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