Imagery: Auto - Large Table of Contents

EXCERPT page containing first few paragraphs. 2024-03-28 04:56:50
UA_SEARCH_BOT_null @ 44.223.31.148

For full access, subscribe here. Or click title to login.

Field Curvature with Two Leica 24mm Lenses

This example compares the Leica 24mm f/2.8 Elmarit-M ASPH to the Leica 24mm f/3.8 Elmar-M ASPH. The 24/3.8 Elmar-M is a newer design, and effectively a full stop slower.

This is a fantastic example comparison, because while the lenses appear similar, they are actually quite different in behavior. No one can doubt the quality of either, yet the comparison shows a large difference.

MTF hints

As seen on the MTF chart below, the 24/3.8 lens delivers much superior field flatness, whereas the 24/2.8 slopes off steadily: field shooting shows that it is due to rearward field curvature. It is hard to take a sharp image of anything planar (flat) without going to f/5.6 - f/8 with the 24/2.8 Elmarit-M.

Although the mouse-over below shows f/2.8 vs f/3.8 (not quite fair), we are not looking for absolutes , but rather general behavior. Namely, that the 24mm f/2.8 Elmarit-M shows an early and strong drop-off in contrast beginning at the middle of the frame, which will be seen as strong blur towards the edges (on a planar subject). By comparison, the f/3.8 Elmar-M has much more consistent sharpness right out to the corners.

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 about 75 cents a day!

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 Leica 24mm f/3.8 Elmar-M,24mm f/2.8 Elmarit-M f/2.8 available in full article

diglloyd Inc. | FTC Disclosure | PRIVACY POLICY | Trademarks | Terms of Use
Contact | About Lloyd Chambers | Consulting | Photo Tours
RSS Feeds | X.com/diglloyd
Copyright © 2022 diglloyd Inc, all rights reserved.