My 40 Nokton SC is from the second batch, that didn't suffer from the reported stiff focusing, and I got it used from another RFF member. Surprisingly compact for such a fast lens, and it performs very well... sometimes with a slight veiling flare that lowers contrast, when, say, shooting into the sun or a bright sky. It seems to be a couple mm longer focal length than the 40 M-Rokkor that came with my CLE in 1982. Assuming the 43mm Pentax-L is truly 43mm, I'd guess the Nokton would be maybe a true 42mm to the Rokkor's 40. The Pentax is glorious with good contrast and saturated colors due to low flare. But it has a bit more barrel distortion than the Nokton (haven't checked the Rokkor for that) and it's physically much longer than the other two. But I like them all, and use them only on the CLE due to its 40mm framelines.