The 28mm has become one of my favored focal lengths more recently, though it started long ago with the Pentax screw-mount 3.5/28mm and then the K-mount 2.0/28mm. Now I greatly enjoy the 28mm Summicron, to the point that was the only lens I took on an 8-day cultural visit to Cuba. That worked so well it made me go "hmm" and I got a Leica Q with its dedicated 28mm. I also have the 2.5/35mm Summarit-S for my S2 which with a 0.8x anti-crop factor brings it to 28mm equivalent. The Pentax K-1 now wears a close-to-28 1.8/31mm Limited lens that I used on an 18-day cruise, while the K3 enjoys the 3.2/21mm Limited which with 1.52x crop comes up about the same. I seem to find it easy to pre-visualize the framing around that angle of view...