At the full aperture the 100mm lens seems to be uniformly soft in the entire frame, but mostly because of a considerably low contrast, and the red dot color is not uniform.
The resolution numbers are not that bad. At the optimum aperture, f/11, the lens performance seems much better due to improved contrast, but the actual resolution is only slightly higher, pretty uniform at 3600 LW/PH (resolution of "37" is the max. theoretical number in this test). There is no increase of the circle size at the sides of the frame compared to the circle size at the center. At the 21st mm the circles become ellipsoidal, with a 1% difference between the extreme diameters (not significant). Chromatic aberration is small.
Analysis at the focal length of 250 mm at various f stops is given here. The best performance is at f/11. Dependence of the image quality in various parts of the full 24x36mm frame is shown below, with the average resolution in hundreds of line widths per picture height (LW/PH) given below each chart.
Even at the full aperture the lens is sharp (resolution of "37" is the max. theoretical number in this test), but the contrast is lower. There is a 1.3% increase of the circle diameter at the sides of the frame compared to the circle size at the center. At the sides the circles look elongated slightly, with a 2.4% difference in the extreme diameters of the ellipse (the deformation is barely noticeable). There is almost no chromatic aberration. This is the optimum focal length for the lens.
Analysis at the 400 mm at various f stops is given here. The lens is the softest at this focal length with the best performance at f/11. Dependence of the image quality in various parts of the full 24x36mm frame is shown below, with the average resolution in hundreds of line widths per picture height (LW/PH) given below each chart.
At 400mm the lens sharpness is still decent but not at the full aperture. Besides some softness when wide open, the loss of contrast is significant. Interestingly, images of the circles are better outside the center of the frame, with better evenness of the red and black colors. There is a 2.7% increase of the circle diameter at the sides of the frame compared to the circle size at the center. At the sides the circles are elongated, with a 3% difference in the extreme diameters of the ellipse. These distortions are high when compared to similar focal length lenses. Chromatic aberration is moderate.
