Method Note 1

Resolution tests were run at a working distance of about 5 meters. The chart was illuminated with a soft box adjusted with a flash meter at each aperture. The camera was on a Bogen 3033/Arca B1 tripod/head combination with a large bean bag weighing down the tripod/head. Two exposures at 1/250th were taken at each aperture with an EOS-1v on Kodak Technical Pan rated at ISO 25 and developed in Technidol. The central autofocus point was centered over the center pattern for each exposure. No focus bracketing was used. Line patterns were read under a compound brightfield microscope at a magnification of 40X.

Measurement were made at the center pattern, a middle pattern, and the far upper right pattern on the two exposures. The highest resolution score for each aperture was recorded. Autofocus function occasionally resulted in variations in lpm scores at the same aperture calculated as described on the poster. Both center resolution and center-weighted resolution performance were calculated. Center-weighted calculation were distributed: 60% center; 30% middle; 10% edge.

Edmund Scientific Lens Resolution Chart

Detail of USAF 1951 test pattern