Pentax K body + Pentax K lens
The originally analog SLR Pentax-K system was the next generation after the popular M42 system, and the similarity in their flange focal depth isn't a coincidence either. More recent PK bayonet locks are AF compatible.
For a long time after the dawn of the digital era, only APS-C sensors were used in PK lock cameras, but in 2015 the Pentax K-1 was introduced, which is outfitted with a fullframe sensor.
One of the best features of the digital PK systems that they can use the older PK lens types without any converters, and a simple recessed ring adapter will allow mounting M42 lenses as well.
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