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Thread: Picture Focus

  1. #1
    Join Date
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    Picture Focus

    I was playing around with my Canon 300D over the weekend and was working with focus etc...

    Tell me, am I right in thinking that a bigger (maybe an f4 for example) aperture will focus on a central object and there is a good chance that the background will become blurred. If the aperture (f19) is smaller there is a greater chance that the background will be in foucs with the rest of the picture.

    I know that there is a lot more to think about than just the aperture, such as shutter speed but in general is this assumption correct.

    Any corrections much appreciated
    Last edited by print-digital; 05-23-2005 at 05:53 AM.
    My flickr photos & my new photoblog & Canon EOS 30D.

  2. #2
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    Quote Originally Posted by print-digital
    I was playing around with my Canon 300D over the weekend and was working with focus etc...

    I am I right in thinking that a bigger (maybe an f4 for example) aperture will focus on a central object and there is a good chance that the background will become blurred. If the aperture (f19) is smaller there is a greater chance that the background will be in foucs with the rest of the picture.

    I know that there is a lot more to think about than just the aperture, such as shutter speed but in general is this assumption correct.

    Any corrections much appreciated

    That is correct. Just remember that bigger aperture (wide open) means blurred background and smaller aperture (closed down) means subject and background in focus. Too though distance from your subject has a lot to do with it also for achieving the right composition.

    Heres a good example of the same photo from my PBase gallery:

    @ F/8



    @ F/2.8

    .

    Canon EOS 30D | Canon EF-S 10-22mm f/3.5-4.5 | Canon 17-40mm f/4L | Canon 24-105mm f/4L IS| Canon 70-200mm f/4L | Canon Speedlite 430EX + Sto-Fen Omni Bounce | Manfrotto 3001BD & 680B/486RC2 | Hoya Super HMC Pro1 Digital Filters | Hitech ND & GND Filters | Bags > Kata R-103 + Lowepro Nova 5 AW

    RawShooter | premium 2006 > My PBase Gallery

  3. #3
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    Theres a lot of difference in those two picutes Bluedog - thanks for the example.
    My flickr photos & my new photoblog & Canon EOS 30D.

  4. #4
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    Bluedog looking at the two images there also seems to be a difference in detail on the flower, much less at f2.8. Is this a real effect of the change in aperture size, a result of reducing file size for posting or due to the slight difference in the magnification? or something else?

  5. #5
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    Quote Originally Posted by Phill D
    Bluedog looking at the two images there also seems to be a difference in detail on the flower, much less at f2.8. Is this a real effect of the change in aperture size, a result of reducing file size for posting or due to the slight difference in the magnification? or something else?
    I can't speak for Bluedog directly, but it looks like the loss of detail is related to the aperture size (depth of field). With the f 2.8 setting, a lot less of the photo is in focus, which shows how much of an affect f-stop can have. Only the center of the flower seems to really be in focus while the back and front petals seem to be starting to blur. If the shot would have been with the f-8 at the same zoom/crop/resolution, the detail would be like the first image shown.

    Erik

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