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Blur by Manual Focus Inconsistency
No one can focus exactly same every time, not even autofocus is always consistent.
Example — Leica M9 rangefinder
The ten actual-pixels crops shown below were from 10 frames shot on the Leica M9 with the 50mm f/0.95 Noctilux-M ASPH. I used a tripod to eliminate any variable except my own eye.
How accurately could I focus the Noctilux? Rather badly! At least on this subject at this distance. Granted, this is f/0.95, and the fine-ness of detail is a challenge for a rangefinder at the distance I shot (perhaps 70 feet). But real life doesn’t provide large high-contrast black and white targets for one’s ease of focusing.
Following this test, I promptly purchased the 1.25X magnifying eyepiece. It definitely helps, but subsequent experience suggests that the 1.4X would be even more advisable to reduce the error further (that’s assuming perfect lens/camera alignment).
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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.
