I have a Pentax K50. Looking at a new lens which is advertised as being for Pentax KAF cameras. Will it work on my camera?
Yes. Pentax has the longest history of keeping lens compatibility. Any K-mount lens will work on the K-50. The mount is descried as KAF, KAF2, KAF3 which corresponds to come refinements done over the years but they are still compatible. Wikipedia has an article explaining all the differences.