The PC Super-Angulon 28/2.8 is compact, and at 600 grams, relatively light. It’s a shift-only lens that allows 11mm on its native 35mm film format. The 62mm image circle covers the 33mm x 44mm GFX sensor, and leaves a bit of room for shift. For comparison, the Canon 24mm f/3.5 TS-E II has a 67.2mm image circle, and allows only 12mm of shift on 35mm film.
The lens has a fairly complex optical design that uses 12 elements in 10 groups. One of the central elements is a floating element for close focus correction. For best performance the lens has to be mounted at its correct flange distance.
As is common for many lenses, the focal length printed on the lens seems to have been chosen by Marketing rather than Engineering, because it’s actually 29.2mm