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Field Example with Canon 14/2.8L II
See also Case Study with Two Leica 24mm Lenses.
These images are with the Canon EF 14mm f/2.8L II at f/4 on the 21MP full-frame Canon EOS 1Ds Mark III.
Focus was near the center. Examination of the image shows strong blur away from the central 1/3 of the image, yet very crisp detail on the leaves at upper right, which are a good 30 feet (10 meters) or so in front of the focus point!
This strong field curvature cannot be overcome by stopping down, even to f/11. While the Canon EF 14/2.8L II exhibits a flat field at close range, with outstanding performance, focusing near infinity exhibits very strong field curvature and thus a strong blur away from the center. Focusing to infinity at center is like focusing at the bottom of a bowl, with the sharpness following the rising edges of the bowl (closer). This could be handy for interior shots, but makes the 14/2.8L unsuitable for many types of outdoor photography with near-infinity focus.
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Diglloyd Making Sharp Images articulates years of best practices and how-to, painstakingly learned over a decade of camera and lens evaluation.
Save yourself those years of trial and error by jump-starting your photographic technical execution when making the image. The best lens or camera is handicapped if the photographer fails to master perfect shot discipline. High-resolution digital cameras are unforgiving of errors, at least if one wants the best possible results.
- Eases into photographic challenges with an introductory section.
- Covers aspects of digital sensor technology that relate to getting the best image quality.
- Technique section discusses every aspect of making a sharp image handheld or on a tripod.
- Depth of field and how to bypass depth of field limitations via focus stacking.
- Optical aberrations: what they are, what they look like, and what to do about them.
- MTF, field curvature, focus shift: insight into the limitations of lab tests and why imaging performance is far more complex than it appears.
- Optical aberrations: what they are, what they look like, and what to do about them.
- How to test a lens for a “bad sample”.
Intrigued? See Focusing Zeiss DSLR Lenses For Peak Performance, PART ONE: The Challenges, or (one topic of many) field curvature.
