So here is the same scene but photographed on the SMC 20mm F4.0 K-mount.
The photos are in order for stops 4, unmarked, 5.6, unmarked, 8, unmarked, 11, unmarked, 16, 22 (no unmarked stop between 16 and 22).
Compared to the 1.4:
The F4 only has a 5-blade aperture, not the 8-blade aperture the 1.4 has.
The F4 has much less vignetting, with it being gone between 5.6 and 8.
The F4 has much less aberrations, with what is there much less noticeable than the 1.4.
Even with the aberrations, comparing the F4 exposures from both, the 1.4 is sharper.
By F8, both lenses are about the same at the center, but the 1.4 still has both mode edge aberrations as well as being sharper.
So, between the two you get some advantages in the 1.4 along with some minuses.
Last post will be same scene on the new 21mm 2.4 Limited lens, to see what 40 years has done for wide-angle lens design.
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