A question about aperture.

Discussion in 'Open Discussion' started by eltictac, Nov 6, 2013.

  1. eltictac

    eltictac Mu-43 Regular

    Feb 12, 2012
    Hi guys.
    I was just wondering about smaller apertures like f11, f16 etc.
    I'm lead to believe higher apertures are good for landscapes when you want a large depth of field?
    But I've heard that m4/3 cameras suffer from diffraction when you go much above f8. And f4 is apparently the sweet spot for many m4/3 lenses.
    So, would somewhere from f4 to f8 provide a large enough depth of field for a good sharply focused landscape?
    And would you consider higher apertures unusable on m4/3 cameras? Or, if not, when do you use them?
  2. phl0wtography

    phl0wtography Mu-43 Veteran

    Apr 15, 2011
  3. dhazeghi

    dhazeghi Mu-43 Hall of Famer Subscribing Member

    Aug 6, 2010
    San Jose, CA
    Every rule has exceptions, but for 95% of the time f/5.6 or f/8 is good for landscapes. Mind you, even at f/8 you will need to choose where to focus appropriately. If you're at 14mm and you focus 16 inches away from the camera, even at f/16 not everything will be in sharp focus.

    The main reasons to use smaller apertures (f/11 or f/16) is for macro where you're focusing very close and the corresponding DoF is much smaller. Even in those cases, people who want the best results use focus-stacking.

    Remember though that the great thing about digital photography is that the per-photo cost is free. So it's well worth experimenting to discover what works for you.
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  4. David A

    David A Mu-43 All-Pro

    Sep 30, 2011
    Brisbane, Australia
    All lenses are diffraction limited at some point, and that's as true for full frame as it is for M43. What is different when you compare M43 to full frame is that diffraction limiting starts to occur at smaller apertures as sensor/film size increases. If you stop and think, you'll recall that depth of field decreases as sensor/film size increases.

    So the first thing is that we can get enough depth of field at F/8 for landscape photography, and even at larger apertures like F/4 and F/5.6 if the closest thing you want in focus is a bit further away. We don't have to stop down as far as people using larger sensor cameras do in order to get the same depth of field so the fact that we run into diffraction limiting at larger apertures than they do isn't the problem you might think it is.

    Second, diffraction limiting doesn't suddenly occur and make the image really unsharp. It occurs gradually. You'll notice that native M43 lenses tend not to have smaller apertures than F/16 while full frame lenses stop down to F/22. If you go to larger format sizes you'd find that with view camera lenses you can stop down to F/64 or perhaps even smaller. Why the difference? Well, probably one of the reasons is that lens makers choose their smallest aperture based on a consideration of depth of field and also diffraction limiting and where they figure the trade off between one and the other becomes impractical. You can use M43 lenses at F/11 or F/16 and you will get more depth of field but the image won't be quite as sharp. Provided you're focussing at the hyperfocal distance in order to get maximum depth of field and have everything back to infinity in reasonable focus, you might gain a couple of feet more in depth of field at close distances over what you'd get at F/8 but for landscape photography if you want things reasonably sharp to infinity the odds are that that few extra feet at the near end of the depth of field range isn't going to be important to your image. If the really close foreground is going to be so important that you need to get it in focus, the odds are that the really far distance isn't going to be as important.

    I don't think you're going to have problems with not enough depth of field for landscape photography using M43 lenses at F/8 or even F/5.6. If you do, then going to a larger format probably isn't going to help because while you're going to be able to stop down further without running into sharpness problems due to diffraction limiting, you're going to get less depth of field anyway. As a rough guide M43 gives you the equivalent of 2 stops extra in depth of field over full frame for the same field of view so you'll get the same depth of field at F/8 using a M43 camera with a 25mm lens as you will at F/16 on a full frame camera with a 50mm lens which gives you the same field of view, but at F/16 on the full frame you'll also be about as close to running into problems due to diffraction limiting as you are at F/8 with the M43 camera. Basically if you're going to run into depth of field problems and need to resort to focus stacking in order to get enough depth of field with M43, you're probably going to have to do the same thing with larger formats too.

    And instead of worrying too much about diffraction limiting on the basis of what some people say about it, why not try taking some photos of subjects at different distances with your lens stopped down to F/11 and F/16 and see how the images look? While you're at it, take some at F/5.6 and F/8 of the same subjects at the same distances and compare the results. See what works for you. Some people are more concerned with razor sharpness than others, and sharpness is more important with some subjects than others. Stopping down to F/11 or F/16 may not be a problem for you with portraits, for example, if you don't want the image so sharp that fine skin detail is visible, and you may want to stop down that far in order to get enough depth of field for some macro shots. Smaller apertures aren't necessarily a "no go region" but they are a "take care" region because you do start trading off sharpness for depth of field. What's important is not trading off more sharpness than YOU want, not how sharp someone else thinks your images should be.
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