Optimal Lens Aperture for Sharp Photos – Digital Photography Tip of the Week

Lenses have many apertures available for use.  Aperture is used to modify the amount of light entering the camera body and can have the effect of increasing or decreasing shutter speeds and depth of field. It also has an effect on the sharpness of your image.

Stopping down a lens (using a smaller f-stop / a larger f number) has the effect of perceived increases in sharpness.  Because of diffraction though, a lenses optimal sharpness occurs a few stops before minimum aperture, which for most lenses is between f8-11 and possible as high as f16.

Until next time, happy shooting.

The digital photography tip of the week is written by the PCIN Assistant Editor, Chris Empey. Chris is a long time photographer and is currently the President of the Niagara Falls Camera Club. You can see more of his photography at his Photo of the Day website.
If you have a tip to send Chris, or a question about digital photography he can address in the newsletter, send it to chris@pcin.net.

Comments 2

  • Holy Crap!!
    What a terribly worded and sort-of-wrong ‘tip.’

    When discussing the lens opening – or f stop – the larger the number the smaller the opening. Thus f 16 is a smaller opening than f 2.8.
    The larger the opening the faster light can get into the camera.
    The smaller the opening, the slower light can get in but the greater the depth of field (the distance in front and behind the actual point you are focussed on that seems to be in focus.)

    If the light stays constant, making the aperture smaller (increasing the number) means that one must decrease the shutter speed (lengthen the amount of time the shutter is open). Think of any exposure as a container. To fill the container you can pour a great deal of water for a short period of time (large opening, fast shutter speed) or you can pour a little water for a long period of time (small opening, fast shutter speed.)

    So, if you are taking portraits and want only the face to be in focus, an f stop like 2.8 might be in order; thus the face would be in focus and the background out of focus. For a landscape, you might be using f16 so that much of what you see from close in front of you to the horizon will be in focus.

    Usually the lens is sharpest at an f stop that is 3 or 4 stops from its maximum aperture. I.E. a lens with an maximum opening of f 2.8 might be sharpest at f5.6 or f 8.

  • Holy Crap!!

    Misleading statement by Lew Lorton too. Chris statement is quite correct when you talk about “refraction” while Lew is talking about faster shutter speed to minimise motion blur, camera shake etc. Both are quite correct depending on what causes the “blur”

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