Methods used with SFRplus chart, Light box exposures and Imatest Master 3.7

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 an Olympus OM-D E-M1 camera, OM-D E-M5 camera or Panasonic Lumix GX7 camera at ISO 200. These are 16 MP cameras that give comparable results in MTF50 tests (see graph). 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, midzonal and corner MTF50 values were determined as well as distortion and chromatic aberrations with Imatest Master.
Camera bodies used:

• 12mm: Olympus 12mm and 12-40mm lenses (E-M5); Panasonic 12-60mm lens (E-M1).
• 14mm: Olympus 12-40mm and Panasonic 14mm lenses (E-M1); Panasonic 12-60mm and 14-45mm lenses (E-M5)
• 20mm: Olympus 12-40mm and Panasonic 20mm lenses (E-M1); Panasonic 12-60mm and 14-45mm lenses (E-M5)
• 25mm: All lenses: (GX7)
• 35mm: All lenses (E-M1)
• 40mm: All lenses with E-M1

Alignment of Camera to Chart: The test chart is on a fixed glass window perpendicular to the floor which is a 12 inch tile floor with grout seams perpendicular to the wall. The tripod and camera are set up next to the window surface to adjust height. Spirit levels mounted to the flash shoe on the camera or camera electronic level are used to level the camera. The camera and tripod are pulled back along the tile floor to the working distance using tile grout lines as a reference. Minor alignments are made in the grid reference view finder to align 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 on out of camera jpg's with Imatest. Examples of Imatest results from another lens test are below.