Controlling DoF

Discussion in 'Beyond the Basics' started by fotogenik, Feb 2, 2006.

  1. fotogenik

    fotogenik TPF Noob!

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    I have seen some pictures recently with incredible DoF control. Specifically the background is a total blur where the subject of the photo is totally sharp.

    My question is how do I control my DoF with no DoF preview? I understand it has to do with focus and aperture, I just am unsure what I need to adjust and which way to adjust it.
     
  2. Meysha

    Meysha still being picky Vicky

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    A narrow depth of field is acheived by using a large aperture (which is a small f/ number - it is relative to your subject but around f/4.5 you'll start to definately notice it)

    For a wide depth of field use a small aperture (which is a large f/ number - above f/8)

    If you focus your camera directly on the subject the depth of field will extend one third infront of the subject and two thirds behind the subject. This is handy to remember when you're having trouble focussing and to try and focus in front of your subject rather than behind.

    You don't need to have a DoF preview to be able to control your DoF. Just set the appropriate aperture value and you'll get varying degrees of 'bluriness' depending on the setting. Look at other people's photos and take note of what aperture they used... then you can expect roughly this same result in your photos.

    Hope that helps!
     
  3. sfaribault

    sfaribault TPF Noob!

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    Learn something every day...

    Steve
     
  4. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    The focal length also plays a part. The DOF is shallower for longer lenses. Also, subject distance...if you are closer to the subject...you can render the background more out of focus, than if you are father away. Also, the further away the background from the subject, the easier it is to make it blurry.


    You can find/download DOF charts for specific lenses/focal lengths.
     
  5. slickhare

    slickhare TPF Noob!

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    since you've got the d50 one thing you could try is to set it up on a tripod and take several shots of the same object with different f/'s and see how the dof changes with each. it'll help you get a feel for what f/ will give you the result you want.
     
  6. ffureel

    ffureel TPF Noob!

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    Just experiment, I have a depth of field preview but never use it because after a while you just will know what a certain aperture will produce.
     

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