PetaPixel

You Can Increase Sharpness a Lot by Stopping Down Just a Little

You probably know that stopping down (i.e. increasing your f-stop number) can increase the sharpness of your subject, but how much should you stop down to boost resolution without losing that nice, creamy bokeh? Roger Cicala did some research on this question and writes:

For those lenses that do benefit, stopping down just to f/2.0 provides the majority of resolution improvement. The difference between wide open and f/2.0 is generally much greater than the difference between f/2.0 and the maximum resolution.

Getting the edges and corners sharp requires stopping down to at least f/4 for most wide-aperture primes, and some really need f/5.6. Stopping down to f/2.8 may maximize center sharpness but often makes only a slight difference in the corners, at least on a full-frame camera.

None of the lenses performed any better after f/5.6 (for the center) or f/8 for the corners. Most were clearly getting softer at f/11.

If you’re using a wide-aperture lens, stopping down to just f/2.0 will reap big gains in sharpness while still keeping the depth-of-field narrow. Furthermore, for some lenses you don’t really even need to worry about stopping down for sharpness, since it hasn’t a relatively negligible effect on the outcome.

Stop It Down. Just A Bit. [LensRentals]


Image credit: Margaritas a la bokeh by ganso.org


 
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  • http://twitter.com/ryandigweed0 ryandigweed

    Nice :)

  • http://twitter.com/TheGoOse Ganso

    Hey! I know that picture! ;)

    Thanks for using it and for the credit, Michael :)

  • http://twitter.com/TheGoOse Ganso

    BTW, I use mainly old manual focus lenses, and I really use that technique a lot: open fully, close a step (click-click-click) and shoot. The example picture is wide open, though :)

  • http://www.cateyefotos.com Brooklyn Photographer

    I always knew the value of this tip generally speaking, but I always wondered just how much, or how little I can afford to stop down and achieve optimal sharpness and dof.

  • Tyler Leeds

    With something like an 85mm 1.4, it’s almost unusable for portraits wide open.  You’re talking about a DOF so thin that it’s impossible to get someone’s whole face (nose, ears, eyes) in focus at the same time…   Mine is very rarely opened wider than F2… and then, only when I’m far enough away from my subject that I can get a useful DOF.

  • http://twitter.com/howardowens Howard Owens

    I read this some where some time ago and then came across it again today in an 50-year-old Nikon F / Nikkormat handbook I have — for prime lenses, optimal sharpness is obtained two stops down from wide open.  On primes I almost never shoot wide open unless I really need the light.