Methods used with SFRplus chart, Light box exposureds and Imatest Master

Tests conducted with the SFRplus chart were photographed with illumination from two modeling lamps each at 45 degrees angle. The images were taken as raw files with a Panasonic GX1 camera at ISO 200. Raw files were converted to high resolution tifs with Adobe Raw Converter. Tif's were analyzed with Imatest Master. Images were analyzed with a 13 region of interest pattern. MTF50 values were summarized as a weighted mean (center - 1.0; part-way - 0.75; corner - 0.25). Central MTF50 and chromatic aberrations were also determined with Imatest. For each autofocus lens, two exposures were taken at each f/stop and the highest value was used. For the manual focus lens, four photograph series were taken with refocus for each series, and the best value was used in the chart.

Photographs were also taken at infinity of an evenly illuminated white box with aperture wide open than at each full stop until f/8. Light drop off was measured with Imatest.