Pentax K-3 Mark IIIvs FX3

GearFrame · Updated March 2026

Pentax Pentax K-3 Mark III Pentax Pentax K-3 Mark III (2021) Starting from £1699 new Best for DSLR enthusiasts & outdoor photographers View Pentax K-3 Mark III
VS
Sony FX3 Sony FX3 (2021) Starting from £3799 new Best for Professional video, documentary & cinematic filmmaking View FX3

GearScore™ Verdict — Which should you buy?

Dslr Enthusiasts & Outdoor Photographers — Pentax K-3 Mark III (2021): The finest APS-C DSLR ever made — class-leading weather sealing, optical viewfinder, 5-axis IBIS, and extraordinary build for photographers committed to DSLR.

Professional Video, Documentary & Cinematic Filmmaking — FX3 (2021): The definitive run-and-gun cinema camera — A7S III sensor quality in a body built specifically for video professionals.

↓ Full specifications below

Pentax K-3 Mark III (2021)

  • DSLR photographers who want the finest APS-C optical viewfinder experience
  • Outdoor and weather photographers who need robust all-weather sealing
  • Pentax lens owners who want to use their existing K-mount glass
  • Photographers who prefer optical viewfinders and refuse to switch to mirrorless

FX3 (2021)

  • Professional videographers and filmmakers who need cinema-quality colour science in a compact body
  • Documentary and run-and-gun shooters who need 4K/120p and built-in XLR audio
  • Sony A7S III owners who want a purpose-built video body alongside their stills camera
  • Gimbal and drone operators who need a compact full-frame cinema camera

Quick take: The pentax k-3 mark iii has the highest resolution at 26mp; the pentax k-3 mark iii is the most affordable. Scroll down for the full spec breakdown.

Full specifications

Specification Pentax K-3 Mark III (2021)FX3 (2021)
Price £1,699 £3,799
Sensor 25.7MP APS-C BSI CMOS (AA-filterless) 12.1MP full-frame BSI Exmor R CMOS (same as A7S III)
Resolution 25.7MP 12.1MP
Video 4K/30p, 1080p/60p 4K/120p, 4K/60p 10-bit, 12-bit RAW output, S-Log3, S-Cinetone
Autofocus SAFOX 13 phase-detect, 101-point (25 cross-type) Real-time tracking with subject recognition (human, animal)
Stabilisation 5.5-stop 5-axis IBIS (Shake Reduction III) 5-axis IBIS — 5 stops
Burst Rate 12fps 10fps mechanical, 10fps electronic
Battery Life 800 shots (CIPA) ~640 shots (CIPA)
Weight 820g body only 715g body only (with XLR handle)
Dimensions 134.5 × 103.5 × 73.5mm 129.7 × 78.0 × 84.5mm
Weather Sealed Yes Yes
Viewfinder Optical pentaprism, 100% coverage, 1.05× magnification None — monitor/external EVF use only
Screen 3.2" tilting touchscreen 3.0" touchscreen, fully articulating
Mount Pentax KF-mount Sony FE mount (full-frame E-mount)
Memory Cards Dual SD UHS-II Dual CFexpress Type A / SD UHS-II slots
Connectivity USB-C, Wi-Fi, Bluetooth USB-C (10Gbps), full-size HDMI, XLR via handle, Bluetooth, Wi-Fi
Genre Pentax K-3 Mark IIIFX3
Landscape
9.0
Wildlife
9.0
Sports & Action
9.0
Portrait
7.0
7.0
Travel
7.0
4.0
Vlogging & Video
4.0
9.0
Low Light
9.0
Street
4.0
Wedding
7.0
⚡ Compare specs side by side Pentax K-3 Mark III prices → FX3 prices →

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