Imagery: Auto - Large Table of Contents

EXCERPT page containing first few paragraphs. 2019-05-21 18:52:37
UA_SEARCH_BOT_null @ 3.85.143.239

Field Curvature with the Canon 16-35mm f/2.8L II

This example shows just how confusing field curvature can be.

In the image below, the left edge is soft, then the image sharpens and remains moderately sharp, then it goes very soft, then it sharpens again, then it becomes soft in the distance. Whew!

Where is our “plane of focus”?! The idea that sharpness is a geometric plane at a fixed focusing distance needs some serious rethinking. Sharpness is a zone. It can be a wavy zone that interacts with the subject in very confusing ways, as seen here.

It should also be clear that depth of field tables, hyperfocal distance, etc, are all rather simple-minded in the face of such behavior: focusing just a little differently can have a radical impact on sharp/unsharp.

A lens with wave field curvature is “unpredictable”, which makes it less desirable for many types of shooting. A flat-field lens, or one with a simple arc of curvature is better.

Article continues for subscribers...

Diglloyd Making Sharp Images is by yearly subscription. Subscribe now for about 13 cents a day ($50/year).
BEST DEAL: get full access to ALL 8 PUBLICATIONS for only 68 cents a day ($249.95)!

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.

Entire frame as shot
Canon 16-35mm f/2.8L II @ f/2.8

diglloyd Inc. | FTC Disclosure | PRIVACY POLICY | Trademarks | Terms of Use
Contact | About Lloyd Chambers | Consulting | Photo Tours
RSS Feeds | Twitter
Copyright © 2019 diglloyd Inc, all rights reserved.