Originally posted by kerrowdown Enjoy your new lens, I've got its first cousin, SMC Pentax A* 200mm F2.8 ED and I love mine to bits.
It's just sematics, I'd guess, and I'm ~certainly~ not looking for an argument - <g>, but I would refer to the K 200/2.5 and A* 200/2.8 as older and younger brothers, while the K 135/2.5 is a first cousin - <g>.
All joking aside, these three lenses do share the same optical construction as each other (and with no other Pentax lenses), and I think that the two 200's are really very, very close.
The two 200's' coatings are different, and the A* does have ED glass (the presence of ED glass in the K is only rumor). Of course, the A* has the A-vs-K electrical differences. However, because of the diameter of the front element, the f/2.5 (as opposed to f/2.8) claimed for the K lens may be a bit "optimistic".
I once had a used but good A* 200/2.8, and then stumbled into a mint K 200/2.5, which I just had to buy (LBA - 'nuf said), and after owning both for a few months, I finally sold off the A* 200/2.8.
I hope you enjoy your new lens, dadipentak.