Confirming our earlier observation that the old “close-down two stops for optimum aperture (sharpest image)” dictum didn’t necessarily hold for current lens designs, here are the results for the Canon 17 mm tilt shift lens. Not only is this lens sharpest wide-open, note that the image quality is substantially higher than that of the two lenses reviewed in the post, Optimum Aperture? .
Unless there is subject matter that is very close to the lens, depth of field is usually not a major concern – especially with a 17 mm lens. Therefore, in most cases, setting the focus at one third of the distance into the subject field and shooting either wide open or a third stop down will yield both maximum image depth of field for the selected aperture at the highest possible image sharpness.