EXCERPT page containing first few paragraphs. 2023-03-29 18:18:24
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Blur by Diffraction
See also the full discussion on diffraction.
Diffraction is a law of physics that no lens can evade, though tilt lenses can play with it.
For any given photosite size, there is a “transition aperture” beyond which the loss of contrast becomes obvious with a top-performing lens, and then accelerates. With average lenses and/or a camera with an anti-aliasing filter, the change is more subtle at first, because the system was not performing all that well to begin with.
For a full-frame 35mm DSLR in the ~24MP range, the transition aperture is f/8, with ~f/9.5 being the last aperture that delivers contrast and brilliance; by f/11 a dullness sets in.
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- 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.
