Sticky Idea: Optimal Lens Sharpness

Discussion in 'Native Lenses' started by SilenX, Nov 19, 2013.

  1. SilenX

    SilenX Mu-43 Regular

    Jun 2, 2013
    Not sure if this has been done but when I searched I kinda came up empty handed.

    I think it might be a good idea to have a stick thread with optimal apertures for lens sharpness, falloff, as well as whether or not the lens is sharp in the center wide open.

    I know sharpness is sometimes considered opinion but have a consensus on certain lenses would still be useful I think. I tend to try and shoot my lenses where they are considered to be the sharpest and would like to have one place where I can go to get the best information on that. That is, instead of scouring the image sample threads to catch a glimpse of discussion on the best apertures for sharpness at center and edge to edge.

    What do you guys think?
  2. phl0wtography

    phl0wtography Mu-43 Veteran

    Apr 15, 2011
    I don't think this is a good sticky, simply because it is not possible. Different sites use different methods, testers suffer from influenced perception (lack of sleep, coffee, lighting conditions et cet.). That's why 3 sites come up with a general idea of a lens' performance, but 3 different results. What should data be based on for this sticky? Who decides? Many will chime in and refer to "some other" site, that got different numerical results.

    Not only that, but sharpness cannot be measured, since it's always perceived sharpness, and a result of different conditions resulting in "sharpness". A lens that resolves higher than another can look softer because of contrast (to name only one condition) and vice versa. Take the Zuiko 135/2.8. On paper it's quite low resolving wide open, yet its high contrast at f/2.8 results in very "sharp" pictures (provided you achieved critical focus). Take the 20/1.7. Considered one of the sharpest lenses for m4/3. Yet, when focusing closely its contrast is so low, that it hurts acuity resulting in unsharp looking photos. There are lots of other examples where specs don't tell you all there is to know about a lens - it's called character. With that in mind, all lenses nowadays are sharp enough. A good shot can be out of focus/ soft. A bad shot with critical focus can never become a good shot though ;)

    Why would you do that?

    There is consensus on every native lens, and even the most common legacy lenses!
    As a rule of thumb, MFT lenses have their sharpest center 1-2 stops in, and show an uniformly sharp frame at f/4.

    I think most have their go-to sites like slrgear, cameralabs, lenstip, dxomark, photozone, to name but the most commonly referred to. Trying to "sum up" all their findings doesn't lead us anywhere.

    Here's some articles on the matter, if you didn't know them by now:

    TOP, and Ming Thein are my first addresses for optics, since both have a deep, and rich background in physics.
  3. wjiang

    wjiang Mu-43 Hall of Famer Subscribing Member

    DxO have measurements like that if you dig deeper into the detailed tests for a lens. I don't find them that useful for comparing lenses but if you want to look at performance of a given lens at different apertures, focal lengths (for zoom), and at position on the frame, they have charts of those.
  4. jyc860923

    jyc860923 Mu-43 Hall of Famer Subscribing Member

    Feb 28, 2012
    Shenyang, China
    I think we all, to some extent, care about the optimal aperture to use, but I stopped thinking like that because the best aperture is for the whole work, not only for the sharpness, falloff or whatever. besides we have plenty of choices in PP for correction.
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  5. SilenX

    SilenX Mu-43 Regular

    Jun 2, 2013
    I guess I didn't quite word what I was thinking quite well enough; had quite a bit of coffee to wake me up this morning.

    While I know not all situations call for the certain aperture that may contain the sharpest image, I thought it would be nice to know what apertures those would be. However, I was unaware that it is roughly f/4.0 for almost all m4/3 lenses to become edge to edge sharp.

    I think this will be a good thing to note in the future. Thanks for all the insight guys.
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