Imagery: Auto - Large Table of Contents

EXCERPT page containing first few paragraphs. 2019-05-21 18:55:12
UA_SEARCH_BOT_null @ 3.85.143.239

Focus Assist Error (Electronic Rangefinder), Nikon D3x

Autofocus can be quite inaccurate, and anything based on the AF system is subject to the same inaccuracies.

Both Nikon and Canon offer a focus assist feature in their DSLR camera bodies, a sort of electronic rangefinder. Many users welcome it as an effective substitute for autofocus when using a manual focus lens.

But as it turns out, Nikon’s focus assist feature offers accuracy that ranges from so-so to awful, as we show here. It is especially inaccurate with f/1.4 lenses. Using f/2.8 lenses seems to help, most likely from twice the depth of field (2 stops slower) as well as improved contrast for the AF system to interpret.

Canon’s AF assist feature (“green dot”) is not necessarily better than Nikon’s. In both cases, results can very widely with the lens and with the conditions, leading to a situation in which one can never really rely upon the feature for even modest requirements.

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.

Variants Live View, Focus Assist available in full article

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.