Smallest aperture before diffraction?

Discussion in 'Open Discussion' started by panyuser, Nov 21, 2012.

  1. panyuser

    panyuser Mu-43 Regular

    Dec 22, 2011
    What aperture are you happy to stop down to, before you start noticing diffraction effects?

    Recently, I wanted to maximise the DOF for a landscape, so chose f8. The tool on Cambridge in Color suggests this is the smallest aperture before diffraction sets in, if printing and viewing at "normal" sizes.

    (Shooting with the GX1.)
  2. elavon

    elavon Mu-43 All-Pro

    Sep 1, 2012
    Tel Aviv Israel
    Real Name:
    I have just read this article this week. The diffraction can be limiting when using very high quality lenses in low ISO and large print. In everyday shooting it has very limited effect and I would not take it into consideration.
  3. Kiwi Paul

    Kiwi Paul Mu-43 Top Veteran

    Aug 15, 2011
    Aberdeen Scotland
    I agree, I think the diffraction issue is over rated, I happily shoot at f8 and the images are fine.
    To be honest I find f8 about as much DOF as you ever need anyway, it's equivalent to using f16 on 35mm format and that is a lot of DOF. Most often I find f5.6 -6.8 to be more than sufficient for most landscape work and at these apertures diffraction is really a none issue.

  4. addieleman

    addieleman Mu-43 All-Pro

    Aug 5, 2010
    The Netherlands
    Real Name:
    When doing close-ups of lenses or mushrooms I usually stop down to somewhere between f/8 and f/11, not further because sharpness suffers a bit too much for my taste. Have to add that I'm an avid pixel-peeper and I'm finicky on sharpness.
  5. elavon

    elavon Mu-43 All-Pro

    Sep 1, 2012
    Tel Aviv Israel
    Real Name:
    You are correct diffraction is more of an issue with macro.
  6. dwig

    dwig Mu-43 Top Veteran

    Jun 26, 2010
    Key West FL
    Note that ANY "rule book" that states an f/stop where diffraction becomes a limiting factor without the necessary additional qualifiers is wrong, period.

    Diffraction is affected by the absolute aperture, not the aperture relative to the focal length. As a result, the f/stop where diffraction becomes a limiting factor (aka Daw's Limit) varies with focal length. The shorter the FL the wider the f/stop.

    Also, diffraction doesn't "kick in", it is always an issue, it's just a question of when it is the limiting factor.
  7. cmpatti

    cmpatti Mu-43 Veteran

    May 8, 2011
    Berkeley, CA
    Furthermore, there is always some limiting factor. Just because the limiting factor becomes diffraction at a particular aperture doesn't mean you shouldn't stop down further if you need to to get appropriate DOF.
  8. lenshoarder

    lenshoarder Mu-43 All-Pro

    Nov 7, 2010
  9. MajorMagee

    MajorMagee Mu-43 All-Pro

    Feb 24, 2011
    Dayton, OH
    It also varies with the wavelength of the light, so most of the time this is just calculated for green light, but would be slightly higher or lower for red and blue. For most of my lenses, in a typical scene with no particular dominant color the sharpest range of apertures falls between f/2 and f/8. There have been cases where I've noticed slight diffraction effects once I went past f/5.6.