Method Note 1

Resolution tests were run at a working distance from the target that allowed the full chart and box to be resolved. 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. Cable release was used. One exposure at 1/250th second was taken at each aperture with an EOS-1v on Kodak Technical Pan rated at ISO 25 and developed in Technidol. For the 85mm test, Provida F 100 film was used. 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. The IS lens was shot with image stabilization turned off. Images were taken with zoom lenses set at 28mm, 50mm, 85mm and 135mm. Prime lenses were also used to compare zoom lens resolution.

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