The Pentax K-3 II, announced in April 2015, is Ricoh's enthusiast flagship APS-C DSLR of its generation — a K-3 refined for outdoor and technical photographers, famously trading the pop-up flash for a built-in GPS module.
It pairs a 24.35-megapixel AA-filterless APS-C CMOS sensor with an improved in-body Shake Reduction unit rated at 4.5 stops, which also enables Pixel Shift Resolution (four-shot full-colour sampling) and AstroTracer, using the GPS and moving sensor to track stars for long unguided exposures. It shoots 8.3fps through a 27-point SAFOX 11 AF system (25 cross-type), has dual SD slots, a 100% pentaprism finder and full magnesium weather-sealed construction.
Its significance lies in those Pentax-only tricks — no rival DSLR offered in-body star tracking — and in its value proposition today: a professional-grade weather-sealed body with access to decades of K-mount glass for £350-£430 used in the UK is arguably the bargain of the DSLR die-off.
UK used-buying checks: the critical known fault is the aperture control block ('solenoid sticking'), endemic to Pentax DSLRs of this era — shoot a burst at f/8 and reject any body producing black or wildly underexposed frames; ask for the shutter count against its 200,000 rating; test GPS lock and an AstroTracer dry-run outdoors if possible since the GPS unit is this model's raison d'être; fire a Pixel Shift frame to confirm the SR unit is healthy; and check both card slots and the flash hot-shoe (remember there is no built-in flash, so an external unit is essential for fill work).