Ok, looking to add to the Pentax lens stock. I have 2-50mm f/1.7 SMC-M's, 135 f/3.5 SMC-M, 35-70 f/3.5 SMC-M, 80-200 f/4.5 SMC-M all Pentax lenses. I also have Vivitar 28mm f/2.0, and Vivitar 70-210mm f/4.5. I am on fence with the Vivitars. I was under the impression when I was younger the Series 1's were decent lenses (mine are not series 1). Now I would like some more primes in K mount. And I know / read enough to stay away from Sears, JC Penny, Focal branded K mounts. But how about some of the others? Tokina lenses from back then ok quality? There are dozens of names of companies that have their names on K mounts. Which ones are decent, and which ones to stay away from?