Aperture in 1/6 stops

Discussion in 'This or That? (MFT only)' started by robcee, Mar 2, 2016.

  1. robcee

    robcee Mu-43 Veteran

    290
    Jan 10, 2016
    Toronto
    Rob Campbell
    Hey mu43ers,

    I was flipping through the exif data on some of my photos this morning and seeing once again that I'm hovering through f1.8-f5.6 most of the time on my lenses. Sometimes I will go higher (smaller apertures) like 6.1 or 7.1, but I find the sweet spot for sharpness between f4.0 and f5.6 on a lot of glass.

    This is a fairly narrow range.

    The Olympus Pro zooms start (with the exception of the 8mm and 300mm) at f2.8. At the standard ⅓ stop, that only gives you 7 stops to play with between 2.8 and 6.1. Since DOF is doubled on m43, maybe it would make sense to halve the distance between stops to give some greater control. Say, 1/6 of a stop between clicks, at least between the 1.8 and 6.1 range.

    That might come into play even more when we get 20MP sensors everywhere and diffraction starts becoming a problem around the f5.6 mark.
     
  2. janneman

    janneman Mu-43 Veteran

    414
    Dec 6, 2012
    Netherlands
    Jan (John) Kusters
    As far as exposure is concerned, my experience is that anything less than 1/2 a stop is pretty much a wash. Even 1 stop is not that big a difference. Take some shots at manual, and go up or down 1/3 stop. Look at them on your computer, how big is the difference? Than correct them to look equal and take a good look again; any difference in gradient or noise? I do not see them.

    The only time it would matter is if you are already 5 or 6 stops off correct exposure. With a 10/12 stop dynamic range, than you might end up in white or black. But again, the difference between full blown and 1/3 stop less than full blow highlights will be hard to see...

    I am glad Oly enables me to set the dials to 1/2 stops, it means I can make a meaningful correction in less clicks.

    I have to noticed any differences in diffraction, but to be honest, I never did any serious testing for that.
     
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  3. robcee

    robcee Mu-43 Veteran

    290
    Jan 10, 2016
    Toronto
    Rob Campbell
    yeah, I didn't even consider this in terms of exposure setting, which is a bit silly. I was merely thinking of the differences in depth of field at each click. You're right that the difference in exposure change between 1-2/6 of a full stop are going to be very minor. ⅓ is more than enough to get fine control in camera.

    PS, @janneman@janneman, may I compliment you on that excellent beard and pipe combination? You have my respect, sir!
     
  4. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    I doubt you'd see much of a DOF change for anything less than half a stop either. Remember too that the blur varies not by f-stop per se, but by the physical size of the aperture. This means that aperture changes on long lenses will have more of a DOF impact since the change in the absolute aperture size will be bigger. Unless you're talking about the very long lenses, then my guess is that even a 1-stop change won't make that big an impact in blur.
     
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  5. eteless

    eteless Mu-43 All-Pro

    Jun 20, 2014
    I just wish I could set shutter speed in 1/3rd stops and aperture in 1/2 stops... I don't really need fine control of aperture however shutter speed can come in handy (sometimes using 1/2 stops on shutter speed means you can't get the correct speed for the lighting frequency and you're forced to change).
     
  6. pdk42

    pdk42 One of the "Eh?" team

    Jan 11, 2013
    Leamington Spa, UK
    You're sort of assuming that there is a "correct" exposure that you can measure that's accurate to less than half a stop. My metering ain't up to that sort of accuracy!!
     
  7. eteless

    eteless Mu-43 All-Pro

    Jun 20, 2014
    It's nothing to do with exposure at all actually, running the wrong shutter speed with flickering lights results in double images or banding... It's more I can't select 1/50th or 1/100th if I'm using half stops, and if I'm using 1/3rd stops it's too accurate for my liking :)

    Hence 1/3rd stops with shutter speed (which can select 1/50th, 1/60th, 1/100th, 1/125th), and 1/2 stops with aperture for speed.
     
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  8. carlosfm

    carlosfm Mu-43 Veteran

    230
    Oct 3, 2015
    Lisbon, Portugal
    With slide film, 1 stop more or less was way off the mark, and 1/2 stop was very noticeable.
    That's why they have invented the spot metering and in the case of the Canon T90, multi-pot metering, where you pressed a "spot" button up to 6 times, measuring different areas, and the camera goes averaging the readings.
    I miss this feature a lot, these days.
     
  9. tkbslc

    tkbslc Mu-43 Hall of Famer

    1/6 a stop of DOF is meaningless. Even 1/2 stop is often hard to notice unless side by side, because there are more variables than just the aperture at play.

    The standard evaluative or multi metering just does that automatically, though.
     
  10. Klorenzo

    Klorenzo Mu-43 All-Pro

    Mar 10, 2014
    Lorenzo
    As others have said 1/3 is already a very small variation for anything.

    BTW diffraction starts to be measurable in test charts around f/5.6 but I wouldn't call that a problem. I'd say that it may be relevant from f/11, for some kind of photography in particular (and sharpening is very good at fixing it).

    Overcoming My f / Entekaphobia

    And the sensor MP count is not going to magnify the diffraction effect in the final picture: a picture shot at f/8 on a 20MP sensor is going to be slightly better then on a 16MP sensor in terms on final resolution (even if the pixel size based diffraction limit is lower).

    If tomorrow they'll release a 100MP sensor for m43 you can still shot at f/5.6 and get the same beautiful pictures as now (even better).
     
  11. carlosfm

    carlosfm Mu-43 Veteran

    230
    Oct 3, 2015
    Lisbon, Portugal
    The word "automatically" doesn't work for me. I like to have control of where I take the measurements.
    It is me who take the photo, I don't like to be commanded by what the camera "thinks" is right.
    I may want to take just two spot readings. Or three. Counting on the camera to average them.
     
  12. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    It's not quite what you're chasing but you can choose between third stop and half stop adjustments. The difference between a third stop and a half stop is 1/6 stop so by playing with your menu setting for exposure adjustment steps you can get third, half, and two third stop intervals between each pair of adjacent full stop settings. What you can't get that way is the 1/6 and 5/6 steps. If you adjust aperture, this lets you adjust depth of field in 1/6 stops apart from those 2 outer sixth stop steps between full stops.

    So, you can get one of the 3 missing sixth stop steps for DOF, but only one of them.