goamules
Well-known
Great examples of how good the Zuiko lens is!
One thing to keep in mind is that a 35mm focal length is not that wide on full frame. 38mm covering that size is even less wide. 40mm is considered a "normal" focal length on 35mm, so the Olympus design is just 2mm shorter, into the "wide zone" for 35mm. On half frame it's slightly long. Though some lenses are indeed wide angle designs, covering say 95 to 100 degrees angle of view, like a Protar V in large format, I doubt that one one of these is "optimized for wide angle" and the other is "optimized for more normal." Both are conventional Double Gauss designs.
Coverage is predominately based on two things; the focal length, and the aperture. The slower the lens, the more the coverage, usually, because of optical dynamics. I note you shot the pen F lens wide open, did it cover the corners better stopped down to F2 or 2.8? 3mm more focal length doesn't do much, but it also helps coverage some. I also note the warmer colors from the Pen-F lens, that your portraits show. The canon is quit cold/blue.
I'm like you, I enjoy a little vignetting in a lot of my photography. Why does the Olympus vignette slightly (I mean dark corners)? Possibly just the design of the barrel, not the optics. They didn't intend for it's coverage to be used on the larger FF size, so built the barrel with a deep inset built in hood, to resist flare. I shoot some 25mm Cine lenses on my Micro 4/3s that are the same way, extremely sharp and 3D in the center, slight spherical aberrations around the edges and vignetting. It looks great to me. Enjoy the 38/1.8, they're one of the best lenses ever made.
One thing to keep in mind is that a 35mm focal length is not that wide on full frame. 38mm covering that size is even less wide. 40mm is considered a "normal" focal length on 35mm, so the Olympus design is just 2mm shorter, into the "wide zone" for 35mm. On half frame it's slightly long. Though some lenses are indeed wide angle designs, covering say 95 to 100 degrees angle of view, like a Protar V in large format, I doubt that one one of these is "optimized for wide angle" and the other is "optimized for more normal." Both are conventional Double Gauss designs.

Coverage is predominately based on two things; the focal length, and the aperture. The slower the lens, the more the coverage, usually, because of optical dynamics. I note you shot the pen F lens wide open, did it cover the corners better stopped down to F2 or 2.8? 3mm more focal length doesn't do much, but it also helps coverage some. I also note the warmer colors from the Pen-F lens, that your portraits show. The canon is quit cold/blue.
I'm like you, I enjoy a little vignetting in a lot of my photography. Why does the Olympus vignette slightly (I mean dark corners)? Possibly just the design of the barrel, not the optics. They didn't intend for it's coverage to be used on the larger FF size, so built the barrel with a deep inset built in hood, to resist flare. I shoot some 25mm Cine lenses on my Micro 4/3s that are the same way, extremely sharp and 3D in the center, slight spherical aberrations around the edges and vignetting. It looks great to me. Enjoy the 38/1.8, they're one of the best lenses ever made.