Difference in sharpness between pre- and auto-focusing

batmura

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Can anyone tell me if there is noticeable difference in sharpness between pre-focused and auto-focused landscape shots? Bryan Peterson recommends pre-fousing, but the thing is some kit lenses don't have pre-focus settings allowing users to choose the distance. So if I simply auto-focus one-third into the frame and set my aperture to something like f/16 or f/22 for maximum amount of sharpnesd, would my shots be different than those pre-focused ones?
 

tirediron

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In most cases, no, at least not noticeably. Pre-focusing is a technique that is going by the wayside as more and more lenses lack the necessary scales with which to do it. Keep a DoF table handy, or, if you have a smart 'phone or PDA, get a DOF application, and then when you're ready to shoot, do the match and figure out what aperture and point of focus you need to acheive your desired look.
 

Big Mike

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It doesn't matter how you focus, it just matters where you focus (the distance from the camera). So if you auto focused or pre-focused to the same distance, there would be no difference.

So if I simply auto-focus one-third into the frame and set my aperture to something like f/16 or f/22 for maximum amount of sharpnesd, would my shots be different than those pre-focused ones?
Don't confuse maximum Depth of Field with Maximum sharpness. While using a very small aperture will give you more DOF, it will also start to give you diffraction, which reduces image quality and sharpness.

So the best thing to do, is to use a DOF chart (now available as smart phone apps). This will allow you to easily figure out a hyperfocal distance. Read up on Hyperfocal focusing techniques.

In a nut shell, that would allow you to figure out what aperture you need, rather than just assuming that you need F16 or F22.

Some landscape photographers won't shoot smaller than F8 or F11, and will bracket their focusing instead. They would take something like three exposures, only changing the focus distance. Thus getting maximum sharpness for various ranges of the scene. Then they use software to combine the best parts of the images into one.
 

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