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EXCERPT page containing first few paragraphs. 2023-03-29 19:37:51

MTF and Sensor Size

A DSLR with a sensor smaller than 36X24mm does not “see” the entire 35mm frame, so lens performance outside its crop is just not relevant, hence the appearance of Nikon “DX” lenses and Canon EF-S lenses, designed to cover only the smaller-size sensor, not the full 36mm X 24mm frame. Nevertheless, users with such cameras who might move to a full-frame camera in the future should consider it relevant for planning lens purchases.

Smaller sensors typically have higher photosite densities (higher spatial resolution on the sensor, regardless of pixel count), and so the demands on lens contrast are higher (remember that contrast drops as resolution increases).

In the diagram below, a Nikon “DX” user need pay attention only out to the ~ 14mm mark; everything else falls outside the sensor. A Canon EF-S format sensor is even smaller. But certain Canon DSLRs crop by 1.3X, so performance out to ~17mm is of interest for those cameras. In this case, the Zeiss 50mm f/2 Makro-Planar will be a world-class lens right out to the corners on such cameras.

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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.

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  • 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.

Example MTF annotated for sensor size

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