Canon EOS R3vs Pentax K-3 Mark IIIvs Sigma fp

GearFrame · Updated March 2026

Canon Canon EOS R3 Canon Canon EOS R3 (2021) From £5999 Best for Sports & photojournalism professionals View Canon EOS R3
VS
Pentax Pentax K-3 Mark III Pentax Pentax K-3 Mark III (2021) From £1699 Best for DSLR enthusiasts & outdoor photographers View Pentax K-3 Mark III
VS
Sigma Sigma fp Sigma Sigma fp (2019) From £1499 Best for Creative filmmakers & experimental photographers View Sigma fp

Which should you buy?

Sports & Photojournalism Professionals — Canon EOS R3 (2021): The pinnacle of Canon's mirrorless lineup for speed — Eye Control AF and 30fps burst in the most rugged body Canon has ever produced.

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.

Creative Filmmakers & Experimental Photographers — Sigma fp (2019): The smallest full-frame camera in the world — Cinema DNG RAW and L-mount flexibility in a pocket-sized body that rewards creative shooters.

↓ Full specifications below

Canon EOS R3 (2021)

  • You shoot sport, motorsport, wildlife, or news at a professional level
  • You need Canon's most reliable and fastest autofocus available
  • You need extreme weather sealing for demanding shooting conditions

Pentax K-3 Mark III (2021)

  • You're a committed DSLR photographer with significant investment in Pentax glass
  • You shoot in extreme weather conditions and place build quality and reliability above everything
  • You prefer optical viewfinder performance and want the best modern APS-C DSLR available

Sigma fp (2019)

  • You're a filmmaker building a cinema rig where the smallest full-frame body is essential
  • You want L-mount compatibility to pair with Sigma Art or Leica SL lenses
  • You prioritise video and cinema colour over stills ergonomics and functionality

Quick take: The pentax k-3 mark iii has the highest resolution at 26mp; the sigma fp is the most affordable; only the canon eos r3, pentax k-3 mark iii are weather sealed. Scroll down for the full spec breakdown.

Full specifications

Specification Canon EOS R3 (2021)Pentax K-3 Mark III (2021)Sigma fp (2019)
Price £5,999 £1,699 £1,499
Sensor 24.1MP full-frame BSI stacked CMOS 25.7MP APS-C BSI CMOS (AA-filterless) 24.6MP full-frame Bayer CMOS
Resolution 24.1MP 25.7MP 24.6MP
Video 6K RAW, 4K/120p, 1080p/180p 4K/30p, 1080p/60p 12-bit Cinema DNG RAW, 4K/24p, 1080p/120p
Autofocus Dual Pixel CMOS AF II with Eye Control AF SAFOX 13 phase-detect, 101-point (25 cross-type) Contrast-detect AF with face/eye detection
Stabilisation 8-stop IBIS 5.5-stop 5-axis IBIS (Shake Reduction III) None (lens-based only)
Burst Rate 30fps electronic / 12fps mechanical 12fps 18fps electronic
Battery Life 620 shots (CIPA) 800 shots (CIPA) 200 shots (CIPA)
Weight 1015g body only 820g body only 422g body only
Dimensions 150.0 × 142.6 × 87.2mm 134.5 × 103.5 × 73.5mm 112.6 × 69.9 × 45.3mm
Weather Sealed Yes Yes No
Viewfinder 0.76" OLED EVF, 5.76M dots, 120fps Optical pentaprism, 100% coverage, 1.05× magnification None
Screen 3.2" fully articulating touchscreen 3.2" tilting touchscreen 3.15" fixed touchscreen
Mount Canon RF Pentax KF-mount Leica L-mount
Memory Cards Dual CFexpress Type B Dual SD UHS-II Single SD UHS-II + CFexpress Type B (via adapter)
Connectivity USB-C 3.2, HDMI full-size, Wi-Fi 6, Bluetooth, LAN USB-C, Wi-Fi, Bluetooth USB-C 3.1, Wi-Fi, Bluetooth
⚡ Compare specs side by side Canon EOS R3 prices → Pentax K-3 Mark III prices → Sigma fp prices →

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