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Diffraction Star Patterns
Part of the rendering style of a lens is the type of diffraction star it produces. This is a matter of taste: pronounced star pattern or a muted one?
A lens with high contrast and that is well corrected for aberrations produces a well defined star pattern, which can be very attractive at night and/or with the sun in the frame.
- The number of “spokes” is related to the number of aperture blades. It can manifest as the number of blades or twice the number of blades.
- Straight-blade lens diaphragms with geometric intersections tend to produce sharp and long and very well defined star patterns.
- Curved-blade lens diaphragms tend to mute the star/spoke effect.
- The presence of subject matter in front of the point source can sometimes create a double-width spoke effect.
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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.