Ultra-wide weather-sealed Pentax 645 prime, 20mm equivalent with SDM AF — the widest lens in the digital 645 system.
The Pentax SMC DA 645 25mm f/4 AL IF SDM AW is an ultra-wide-angle lens for the Pentax 645 digital medium format system, providing a perspective equivalent to approximately 20mm on 35mm format. The AW (All Weather) designation indicates comprehensive weather sealing for outdoor use in rain, dust, and cold conditions.
The 25mm focal length on the 645 sensor provides dramatically wide coverage ideal for landscape, architectural, and interior photography where maximum perspective is needed. The SDM (Supersonic Drive Motor) provides quiet autofocus, and the IF (Internal Focus) design maintains constant barrel length during focusing.
Build quality is professional-grade with comprehensive weather sealing matching the Pentax 645D and 645Z bodies. The aspherical lens element controls distortion, and the SMC coating ensures excellent contrast and flare resistance. The lens is designed specifically for digital 645 sensors with optimised image circle coverage.
The DA 645 25mm f/4 commands strong prices on the used market as the widest autofocus lens in the Pentax 645 digital system. For landscape and architectural photographers using the Pentax 645D/Z, it provides a wider perspective than any other native lens with the weather-sealed reliability essential for outdoor work.