Originally posted by furby I'm interested in getting some and wanted to know the difference between smc, S-M-C and Super takumars. Can someone please educate me?
The Asahi Optical Historical Club has a history of the lens mounts, operations and coatings here
Screwmounts
It helps to understand the sequence of Spotmatic and ES cameras features and specifications before attempting to categorize the lenses - there are confusing elements.
Here is a resource for the M42 Pentax cameras (and lenses elsewhere on the site)
Die Cast Pro - Spotmatic Family Traits
Paul Provencher (author of the site) says in the comments section that distinguishing all the lens engravings would take another table, and maybe a serial number database.
Another enthusiast has started a database here
www.m-fortytwo.info - index page
These resources are packed with info on the Spotmatic years - thet make a great time-killer on a rainy or winter Sunday.
Sorry I can't be more help