The sample I 'm ready to buy is the first S-mount (short) version, with its N-F adapter, so it's a rather "rare" item.
2600 short units build and only 600 "long" F-units according to "photosynthesis".
Thank you, Bjørn and Frank for the reply...I know what a bellows lens is. My first "macro" (in 1980) was a SMC Pentax 4/100 in K-mount with auto-bellows on my MX, I was just 16 old and happy to try macro...I recently bought this old 4/100 SMC -K lens and a Nikon to K adapter to use it on my PB4...but I also use an old and very good S-Planar 4/74 or a new 4/105 Apo-Rodagon (no, I didn't find an Apo-EL Nikkor, alas !)
I'd like to see some images taken with the 4/135 too ! I'll show you mine when I get the lens...