EXCERPT page containing first few paragraphs. 2023-12-02 23:04:25
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Testing for Longitudinal Chromatic Aberration (LOCA)
To test for axial chromatic aberration (ACA), specular highlights work well.
Specular highlight test
Test for longitudinal chromatic aberration with any subject that has a specular highlight (e.g., crumpled aluminum foil, interior of a barn with cracks of light, etc).
- Focus once, then switch the lens to manual.
- Shoot the full aperture series through f/8 (e.g., f/1.4, f/2, f/2.8, etc). The improvement by aperture can thus be evaluated.
- Process with daylight color balance, and look for violet or purple fringing.
- Focus properly; when the image is out of focus to begin with the effects will take more stopping down to control.
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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.
