Pentax have a long established and fine reputation for backwards compatibility, and it is a tribute to the finely designed K mount that even today it offers a remarkable degree of functionality with lenses going back to even the 1950s. The mount has regularly updated, with the advent of electronics and AF adding contacts and levers to the mix, but still any Pentax K mount lens that has an “A” on the aperture ring will function fully and normally, without any special requirements or adapters. Earlier lenses will still function, but manually and with restrictions.
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