How to assess focus sharpness of RAW files?

Question

What's the best technique to sort imported RAW files for focus sharpness?  I'm a nature photographer (birds, bugs, flowers, whales, & landscapes) taking telephoto & macro shots with Canon 20D and Canon L series lenses.  My current techique is to sort for sharpness by viewing at 1:1 and rejecting the RAW file if it is not tack sharp (eg. eye of the animal which is my focus point).  Am I rejecting some great photos that do not appear to be tack sharp right out of the camera (at 1:1 view)?  Thanks for sharing your techniques for assessing focus sharpness!

Answer 1

The in focus sharpeness created by the lens being exactly in focus on the plain you intended is a different thing to the sharpening appied to an image in processing, which is basicaly localised contrast enhancement. The sharpness of the actual point of focus is a factor of the quality of the lens (combined with your technique in getting it in the right place and avoiding camera shake of course), if the technique is correct, using L series camera lenses should create a very sharp point of focus at any aperture, poorer quality lenses (and indeed even the occasional L lens, are never totally sharp because the are never actually in focus and increasing some sensors out resolve even the best lenses which can result in soft looking images on such cameras as the 1 D mk III if the focus is placed to the edges of the sensor) RAW files imported into LR have a  sharpening applied by default to deal with a specific problem described as follows. Digital capture sensors typically have an anti aliasing filter in front of the sensor which help to eliminate moire artifacts as edges come into conjunction at the resolution of the photosite array. That's a complicated way to say that if you have a thin straight line and you rotate it on the sensor so that it is almost in alignment with a line of photosites, there will come a point where the thin straight line will randomly register on one side or the other of a boundary between photo sites. The anti aliasing filter blurs and widens the line to minimize the moire effect that this causes. In doing so, some resolution is lost.  Input sharpening is the operation of setting edge boundary contrasts to recover the perception of resolution to reduce this problem this will enable you to judge accurately if you have actually hit the right spot with your focus, by viewing the image 1:1 before you start adding any contrast enhancements. Input sharpening is applied by default (unless you turn it off in LR) and little or no extra is usually required. Output sharpening is required for print and web images and this is also done automatically by LR using the selections in the export mode.
Creative sharpening can be done if you really want to using the brush tool in LR, but applying over all sharpening as a creative technique using LR (or any other software for that matter) should be done with caution if at all.
Processing sharpening enhances an image, it doesn't make an out of focus image somehow in focus.