a Question about focus and blur

Discussion in 'Digital Photography' started by BlindSoul, Dec 24, 2010.

  1. BlindSoul macrumors 6502

    Joined:
    May 30, 2010
    Location:
    Israel
    #1
    Hello.

    My sister got a Nikon D5000 Camera with AF Nikkor 18 - 105 mm Lens, And it's still new and we barely know how to use it.
    I've been wondering how we can do the same effect as on this photo:
    [​IMG]

    where you can focus on one object and modify the blur you want.


    Thank you so much!
     
  2. ComputersaysNo macrumors 6502

    ComputersaysNo

    Joined:
    Apr 15, 2010
    Location:
    Amsterdam
    #2
    Start googling about 'aperture'. The wider it gets, the more blurry the background will be.

    edit*

    http://en.wikipedia.org/wiki/Aperture

    Photo1 - lots of blurry background, Photo2 front-to-back sharpness
    [​IMG]
     
  3. El Cabong macrumors 6502a

    Joined:
    Dec 1, 2008
    #3
    According to the EXIF data, the photo was shot at a focal length of 35mm with an f/2.0 aperture on an Olympus E-5, which means that, to achieve the same effect with your camera, you'd need to shoot that exact shot at about 46mm at around f/2.8 (which you can't, with your current lens). Without getting into the details, it has to do with sensor size/depth of field relationship.

    In any case, look into depth of field and its relationship to aperture, and also into getting a large aperture lens such as the 35mm f/1.8.
     
  4. dllavaneras macrumors 68000

    dllavaneras

    Joined:
    Feb 12, 2005
    Location:
    Caracas, Venezuela
    #4
    You can get that effect by using a wide aperture lens (f1.4-f2). Focal length also plays its part, since a longer focal length will compress the DOF more than a wide angle lens. Finally, the distance from the subject is also involved. Generally, the closer you are to the subject, the shallower the DOF.

    See this shot as an example. It was taken at a focal distance of 50mm. EXIF: 1/500, f2.2, ISO 400. IT was taken at about 40 cm from the hand.

    [​IMG]
     
  5. bubulindo macrumors member

    bubulindo

    Joined:
    Jul 16, 2010
    Location:
    Neither here, nor there...
    #5
    Depth of field...

    You should be searching for the terms "depth of field" which translates into the how deep does the focus on a picture go.

    I was taught that to achieve this you should put the camera in it's highest aperture, the biggest focal length you can have (although 105 can be an overkill) and shoot.
    Be careful as to where exactly you are pointing the focus at, sometimes you get a depth of a few millimeters that are focused, meaning that if you focus on something that is a few millimeters before or after your subject it will be unfocused.

    The best to do is to try it by yourself. Start in aperture priority mode, put the aperture in the lowest number you can have and take a couple of shots with different focal lengths and see what you get. :)
     

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