• 35mm 847.3mm2
  • 24.2 megapixels
  • ISO 100 - 51,200
  • APS-C 361.2mm2
  • 25.7 megapixels
  • ISO 100 - 1,600,000

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Differences

Sony A9 advantages over Pentax K-3 III

  • Larger sensor
    35mm vs APS-C
    More sensor area. Bigger is (generally) better.
  • Bigger pixels
    ~ 5.93 vs 3.76 microns
    Better low-light and dynamic range (all else equal)
  • Tiltable Screen
    Tiltable vs Fixed
    Tilt the screen for shooting flexbility
  • NFC
    Yes vs No
    Simplifies pairing your camera with supported phones
  • On-sensor phase detect
    Yes vs No
    Usually improves live view and video AF performance
  • Faster JPEG shooting
    20.0 fps vs 12.0 fps
    Faster JPEG shooting (burst mode)
  • Bigger JPEG buffer
    364 vs 30 shots
    Take more JPEG shots before waiting (burst mode)
  • Slow-motion videos
    Yes vs No
    Shoot slow-motion videos
  • Faster shutter
    1/32000 vs 1/8000 sec
    Shoot wide open in bright light

Pentax K-3 III advantages over Sony A9

  • Lens selection
    Excellent vs Good
    Better lens selection gives you more options
  • Less expensive
    $2344 vs $2995*
    Save money for lenses or accessories
  • High resolution composite
    Yes vs No
    Combine multiple shots to form a super hi-res version
  • Longer stills battery life
    More info 800 vs 650 shots
    Capture more photos
  • Top deck display
    Yes vs No
    Check settings with a screen on top of the camera
  • Newer
    4 years vs 8 years old
    Newer cameras often support more advanced features
  • Higher-res screen
    540k vs 360k pixels
    More detail on the screen lets you judge focus and composition
  • More viewfinder magnification
    1.05x vs 0.78x
    Get a bigger view of the scene through the eye-level viewfinder
  • Optional anti-aliasing filter
    Optional vs Fixed
    Lets you choose sharper photos or reduced moiré
  • Higher extended ISO
    1600000 vs 204800 ISO
    Higher extended ISO can give more low-light flexibility

Similarities

Common Strengths

  • Focus peaking
    Both provide
    Your camera will highlight what's in focus
  • Eye-level viewfinder
    Both provide
    You'll be able to frame photos even when the sun is out
  • In-Camera Image Stabilization
    Both provide
    Reduces the effects of camera shake at slower shutter speeds
  • Shoot 4K video
    Both provide
    Make sure you have a fast computer
  • Touchscreen
    Both provide
    Interact with your camera just like your smartphone
  • Built-in Wi-Fi
    Both provide
    Share your photos wirelessly
  • Built-in Bluetooth
    Both provide
    Always-on wireless connectivity
  • External Mic Jack
    Both provide
    Improved sound fidelity when shooting video
  • HDMI out
    Both provide
    Use HDMI output to monitor or review video
  • Hot shoe
    Both provide
    Off-camera flashes open new possibilities
  • Dual card slots
    Both provide
    Gives you more storage flexibility
  • Headphone jack
    Both provide
    Monitor audio recording while you shoot video
  • Bulb shutter
    Both provide
    Hold the shutter open manually for long exposures

Common Weaknesses

  • Tilt-swivel screen
    Neither provide
    Tilt and swivel the screen for maximum shooting flexibility
  • In-camera panoramas
    Neither provide
    Stitches multiple shots into a panoramic photo
  • Built-in GPS
    Neither provide
    Geotag your photos
  • Internal flash
    Neither provide
    Useful in a pinch for fill flash

User reviews

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Buy the Sony A9
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Buy the Pentax K-3 III
Body Only
  • Body Only
  • Kit with 20-40mm F2.8-4 Lens
  • Kit with 55-300mm f/4.5-6.3 Lens
All K-3 III Deals

Review Excerpt

  • New sensor offers incredible performance; Excellent image quality at low & high ISOs; Very good dynamic range; Phenomenal 20fps burst speed & deep buffer; Very good battery life for a mirrorless; 4K video; Dual card slots.

  • Slow buffer clearing; Only one card slot is UHS-II compatible; Touchscreen underutilized; No lossless RAW compression option; No 4K/60p option.

  • Read our Sony A9 Review

The Competition

Compared to Leica SL (Typ 601)

Sony A9
Leica SL (Typ 601)
  • $2997
  • 35mm
  • Less expensive
  • In-Camera Image Stabilization
  • $3802
  • 35mm
  • Built-in GPS
  • Top deck display

Compare Sony A9 vs Leica SL (Typ 601)

Pentax K-3 III
Leica SL (Typ 601)
  • $1847
  • APS-C
  • Less expensive
  • In-Camera Image Stabilization
  • $3802
  • 35mm
  • Larger sensor
  • Bigger pixels

Compare Pentax K-3 III vs Leica SL (Typ 601)

Compared to Pentax KP

Sony A9
Pentax KP
  • $2997
  • 35mm
  • Larger sensor
  • Bigger pixels
  • $999
  • APS-C
  • Lens selection
  • Less expensive

Compare Sony A9 vs Pentax KP

Pentax K-3 III
Pentax KP
  • $1847
  • APS-C
  • Shoot 4K video
  • Touchscreen
  • $999
  • APS-C
  • Less expensive
  • Tiltable Screen

Compare Pentax K-3 III vs Pentax KP

Compared to Sony A7R III

Sony A9
Sony A7R III
  • $2997
  • 35mm
  • Bigger pixels
  • Fast startup
  • $2151
  • 35mm
  • Less expensive
  • High resolution composite

Compare Sony A9 vs Sony A7R III

Pentax K-3 III
Sony A7R III
  • $1847
  • APS-C
  • Lens selection
  • Longer stills battery life
  • $2151
  • 35mm
  • Larger sensor
  • Less expensive

Compare Pentax K-3 III vs Sony A7R III

Compared to Canon 90D

Sony A9
Canon 90D
  • $2997
  • 35mm
  • Focus peaking
  • Larger sensor
  • $1099
  • APS-C
  • Less expensive
  • Tilt-swivel screen

Compare Sony A9 vs Canon 90D

Pentax K-3 III
Canon 90D
  • $1847
  • APS-C
  • Focus peaking
  • In-Camera Image Stabilization
  • $1099
  • APS-C
  • Less expensive
  • Tilt-swivel screen

Compare Pentax K-3 III vs Canon 90D

Compared to Sony A9 II

Sony A9
Sony A9 II
  • $2997
  • 35mm
  • Less expensive
  • $4498
  • 35mm
  • Newer

Compare Sony A9 vs Sony A9 II

Pentax K-3 III
Sony A9 II
  • $1847
  • APS-C
  • Lens selection
  • Less expensive
  • $4498
  • 35mm
  • Larger sensor
  • Bigger pixels

Compare Pentax K-3 III vs Sony A9 II

Compare Other Cameras?