Petzval field curvature, also known simply as Petzval curvature, refers to a specific optical characteristic of a lens system, particularly related to how the lens focuses light onto a plane. Named after the Hungarian physicist Joseph Petzval, this concept is essential in understanding and designing photographic and imaging systems. In an ideal optical system, all rays of light originating from a point source should converge to a point on the image plane, producing a flat image.
Articles by others on the same topic
Petzval field curvature is an optical aberration in which the preferred image surface is curved rather than planar. Even an otherwise sharply imaged flat object can therefore have its center in focus on a flat detector while its edges are out of focus.
A useful test images a flat pattern and refocuses separately for central and peripheral features. If the best-focus detector position changes with field position, field curvature contributes. Unlike optical distortion, it changes where sharp focus occurs rather than simply displacing image positions. Additional optics can flatten the useful image surface, subject to other optical aberrations.