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Thread: Focus Question.

  1. #1
    Starting to think outside of the box icicle's Avatar
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    Focus Question.

    Can a person use a smaller aperture to focus closer to the lens when you run out of focus adjustment?

    I know that when you go smaller you can increase you DOF. and when you go larger you get a shallow DOF.

    but does it work in opposite to?
    if one has a non macro lens but wants to take a close-up beyond the minimum focus distance of the lens.

    lets say if I use a 18-55 mm zoom lens with a minimum focus distance is 9.8 in.
    and I want to take a close-up at 5.5 in, will using a smaller aperture like a f/32 do the trick?
    Feel Free to edit my photos, However please explain what you did to them.

  2. #2
    Be serious Franglais's Avatar
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    Re: Focus Question.

    Yes you can use a small aperture to get greater depth of field (shorter focal length will also increase the depth of field but will also change the view).

    However even at 18mm f32 a subject at 5.5 inches will be out-of-focus if the lens is focussed at 9.8 inches. Do the calculation for yourself here :

    http://www.dofmaster.com/dofjs.html

    How about using a close-focussing screw-in filter on the front of your lens? It won't be as good as a macro lens but it might do the job.
    Charles

    Nikon D800, D7200, Sony RX100m3
    Not buying any more gear this year. I hope

  3. #3
    Senior Member freygr's Avatar
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    Portland, OR, USA
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    Re: Focus Question.

    Quote Originally Posted by icicle
    Can a person use a smaller aperture to focus closer to the lens when you run out of focus adjustment?

    I know that when you go smaller you can increase you DOF. and when you go larger you get a shallow DOF.

    but does it work in opposite to?
    if one has a non macro lens but wants to take a close-up beyond the minimum focus distance of the lens.

    lets say if I use a 18-55 mm zoom lens with a minimum focus distance is 9.8 in.
    and I want to take a close-up at 5.5 in, will using a smaller aperture like a f/32 do the trick?
    This is true, but in micro-photography the distances you are asking is almost a 2X. There isn't a lens with a normal angle of view on any camera I know off which will bring both objects into focus but for a pinhole.

    Franglais gave you a link and there is a Palm App also, which is very good DOF Master.
    GRF

    Panorama Madness:

    Nikon D800, 50mm F1.4D AF, 16-35mm, 28-200mm & 70-300mm

  4. #4
    Panarus biarmicus Moderator (Sports) SmartWombat's Avatar
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    Re: Focus Question.

    I would use an extension tube, rather than put glass in front of the lens.
    PAul

    Scroll down to the Sports Forum and post your sports pictures !

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