Yesterday, I reported on the results on simulations of a Zeiss Otus 55/1.4 at various f-stops, and showed how MTF-50 values translated into picture sharpness with simulated photographs. Today I’ll do something similar, but varying motion blur instead of f-stop. I set up the sim with the pixel pitch set to 4.88 um (same as a7R or… [Read More]
What’s MTF50 = x look like: sim pix
Last week, I wrote this post on producing images that show visually the effect of image capture blur on Bayer-CFA cameras. I briefly discussed this simulation-based approach: Start out with a slanted edge. Dial in some diffraction, some motion blur, some defocusing, take the captured image, run it through a slanted edge analyzer, and get… [Read More]
2 180mm lenses on the Sony a7II
The title is a bit misleading. I’ve been asked to compare the Sony 70-200mm f/4 OGG FE lens to the Leica 180mm f/3.4 Apo-Telyt-R. For this test, I set the Sony lens to about 180mm. The camera was the Sony alpha 7 Mark II, hereafter called the a7II. It was tripod mounted with a RRS… [Read More]
What’s MTF50 = x look like?
When I did the analyses of images produced with the Sony a7R and a7II and the Sony 70-200mm f/4 OSS FE lens with mountings of varying stability, I used MTF50 as a metric for sharpness, and presented the results as graphs with that metric as the vertical axis. Over on the DPR E-Mount forum, my… [Read More]
Field curvature with the 24mm f/3.5 PC-E Nikkor
A reader suggested that the disappointing showing of the PC-E 24mm f/3.5 Nikkor D ED might have been caused by field curvature. In order to check that out, I made an aperture series focusing in the upper right corner. The scene: The upper right corner, blown up 3:1: Looks a lot better, doesn’t it? Now… [Read More]
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