These are the best Pentax lenses for architectural photography when you want rectilinear discipline, controlled flare, and weather-ready handling for interiors, facades, cityscapes, and blue-hour scenes—across APS-C and full-frame K-mount bodies. Full-frame shooters should anchor with the HD PENTAX-D FA 15–30mm f/2.8 ED SDM WR, a tank-tough ultra-wide with strong coma control and crisp corners for tight interiors and night city lines, and add the jewel-like HD PENTAX-D FA 21mm f/2.4 Limited DC WR for a compact, sealed wide with modern coatings and story-rich micro-contrast; classic primes like the smc/HD PENTAX-FA 31mm f/1.8 Limited deliver wide-normal discipline and elegant sunstars for exterior details. For extreme rectilinear reach and low distortion, third-party FF options are standouts: the IRIX 15mm f/2.4 (K-mount) with a long, precise manual throw and excellent corner hold, the IRIX 11mm f/4 for sweeping lobbies and atriums, and the Laowa 12mm f/2.8 Zero-D (K) for near-zero distortion in cramped rooms; budget explorers can consider the Samyang 14mm f/2.8 (K), minding mustache distortion with careful profiling. APS-C kits shine with the HD PENTAX-DA★ 11–18mm f/2.8 ED DC AW as the pro ultra-wide—fast, sealed, corner-clean—and the smc/HD PENTAX-DA 12–24mm f/4 for rectilinear travel and real estate; tiny Limited primes keep you discreet on site: the HD PENTAX-DA 15mm f/4 Limited (cult sunstars, great flare control) and HD PENTAX-DA 21mm f/3.2 Limited (close-focus intimacy) pair perfectly with the sealed HD PENTAX-DA 20–40mm f/2.8–4 Limited DC WR for walk-around detail work. When true perspective control matters, Pentax shooters have excellent tilt-shift paths: the Samyang/Rokinon T-S 24mm f/3.5 (K-mount) provides ±12mm shift and ±8.5° tilt with independent rotations for line-true facades and tabletop plane-of-focus control; medium-format adaptations expand movements—mount the PENTAX 67 75mm f/4.5 Shift for huge image circle and elegant rendering, or use a Mirex-style T/S adapter with PENTAX 645 wides (35/3.5, 45/2.8, 55/2.8) to add generous shift plus tilt for interiors and stitched panos without bending verticals. Across the lineup, Pentax strengths elevate architecture: HD/SP coatings preserve contrast against sunballs and glass, in-body Shake Reduction steadies handheld scouting frames (disable SR on tripod), Pixel Shift yields micro-detail on static scenes, electronic level and live-view grids keep horizons honest, and WR/AW lenses plus sealed bodies mean you keep working in rain and spray. Practical picks: choose D FA 15–30/2.8 and D FA 21/2.4 Limited for a sealed FF duo, add IRIX 15/2.4 (or Laowa 12/2.8) for rectilinear extremes; on APS-C, run DA★ 11–18/2.8 or DA 12–24/4 for ultra-wide coverage, with DA 15 Limited/DA 21 Limited and DA 20–40 Limited WR for compact detail sets; for movements, use the Samyang T-S 24/3.5 as the modern workhorse, the 67 75/4.5 Shift for large coverage on K-1/K-3 bodies, or a 645 wide via a T/S adapter when both tilt and shift are needed. Field tips: level the body and “rise” with shift to keep verticals parallel, rotate the shift axis for diagonal corrections, stop down to f/5.6–f/8 for edge discipline (f/8–f/11 on the widest lenses), shade bulbous fronts to tame flare, bracket exposures for bright windows, and stitch shifted frames for high-res, line-true panoramas. Whether you’re threading glass-and-steel towers, capturing vaulted interiors, or rendering historic brickwork with accurate geometry, the best Pentax lenses for architectural photography combine rectilinear optics, movement options, and rugged sealing—so your lines stay straight, your corners stay clean, and your files print big and true.