• APS-C 355.7mm2
  • 14.2 megapixels
  • ISO 100 - 3200
  • APS-C 366.6mm2
  • 24.4 megapixels
  • ISO 100 - 51,200

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Differences

Nikon D3100 advantages over Pentax K-3

  • Less expensive
    $700 vs $1150 (MSRP)
    Save money for lenses or accessories
  • Bigger pixels
    ~ 5.01 vs 3.91 microns
    Better low-light and dynamic range (all else equal)
  • Fast startup
    ~0.40 vs 0.9 sec
    Faster startup lets you catch the moment
  • Lighter weight
    777g vs 1240g
    Lighter weight

Pentax K-3 advantages over Nikon D3100

  • Focus peaking
    Peaker vs Non-peaker
    Your camera will highlight what's in focus
  • In-Camera Image Stabilization
    Yes vs No
    Reduces the effects of camera shake at slower shutter speeds
  • Higher effective ISO
    1,216 vs 919 iso
    Take photos in low light with less noise
  • More dynamic range
    13.4 vs 11.2 evs
    Retain detail in highlight and shadows
  • More telephoto lens reach
    203 mm vs 83 mm
    Capture objects farther away with the kit lens
  • Top deck display
    Yes vs No
    Check settings with a screen on top of the camera
  • External Mic Jack
    Jack vs No jack
    Improved sound fidelity when shooting video
  • More cross-type AF points
    25 vs 1
    Cross-type AF points improve autofocus performance
  • Pentaprism viewfinder
    Pentaprism vs Pentamirror
    Much better viewfinder picture fidelity
  • More dots on screen
    1037k vs 230k dots
    Can mean greater resolution or a brighter screen
  • Less shutter lag
    0.14 vs 0.28 sec
    Focus and take a photo quickly (wide angle)
  • More viewfinder magnification
    0.63x vs 0.53x
    Get a bigger view of the scene through the eye-level viewfinder
  • More pixels
    24.4 vs 14.2 megapixels
    Higher resolution photos
  • Shoots 60p video
    Yes vs No
    A faster framerate can give you more editing options
  • Dual card slots
    Yes vs No
    Gives you more storage flexibility
  • More AF points
    27 vs 11
    More AF points improve autofocus
  • Headphone jack
    Yes vs No
    Monitor audio recording while you shoot video
  • Optional anti-aliasing filter
    Optional vs Fixed
    Lets you choose sharper photos or reduced moiré
  • Faster JPEG shooting
    7.1 fps vs 2.9 fps
    Faster JPEG shooting (burst mode)
  • Faster shutter
    1/8000 vs 1/4000 sec
    Shoot wide open in bright light
  • Higher extended ISO
    51200 vs 12800 ISO
    Higher extended ISO can give more low-light flexibility

Similarities

Common Strengths

  • Eye-level viewfinder
    Both provide
    You'll be able to frame photos even when the sun is out
  • Internal flash
    Both provide
    Useful in a pinch for fill flash
  • HDMI out
    Both provide
    Use HDMI output to monitor or review video
  • Hot shoe
    Both provide
    Off-camera flashes open new possibilities
  • 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
  • Touchscreen
    Neither provide
    Interact with your camera just like your smartphone
  • In-camera panoramas
    Neither provide
    Stitches multiple shots into a panoramic photo
  • Tiltable Screen
    Neither provide
    Tilt the screen for shooting flexbility
  • Built-in Wi-Fi
    Neither provide
    Share your photos wirelessly
  • NFC
    Neither provide
    Simplifies pairing your camera with supported phones
  • Built-in Bluetooth
    Neither provide
    Always-on wireless connectivity
  • Built-in GPS
    Neither provide
    Geotag your photos
  • On-sensor phase detect
    Neither provide
    Usually improves live view and video AF performance
  • Slow-motion videos
    Neither provide
    Shoot slow-motion videos

User reviews

Buy From

Your purchases support this site

Your purchases support this site

Buy the Pentax K-3

Review Excerpt

  • Top-notch image quality; Great ergonomics in a compact body; Unique on-demand low-pass filtering; Broad sensitivity range; Large and bright viewfinder for an APS-C camera; Dual card slots; Optional Wi-Fi remote control

  • AE Lock button is poorly located; Below-average battery life for a DSLR; Rather dated-looking menu system; Requires a different battery grip accessory than its predecessors; Less third-party support than some rivals

The Competition

Compared to Sony DSLR-A380

Nikon D3100
Sony DSLR-A380
  • $700
  • APS-C
  • Lens selection
  • Less expensive
  • $849
  • APS-C
  • In-Camera Image Stabilization
  • Tiltable Screen
Pentax K-3
Sony DSLR-A380
  • $699
  • APS-C
  • Lens selection
  • Focus peaking
  • $849
  • APS-C
  • Less expensive
  • Bigger pixels

Compared to Sony A33

Nikon D3100
Sony A33
  • $700
  • APS-C
  • Lens selection
  • Fast startup
  • $540
  • APS-C
  • In-Camera Image Stabilization
  • In-camera panoramas
Pentax K-3
Sony A33
  • $699
  • APS-C
  • Lens selection
  • Focus peaking
  • $540
  • APS-C
  • Less expensive
  • Bigger pixels

Compared to Pentax K-r

Nikon D3100
Pentax K-r
  • $700
  • APS-C
  • Less expensive
  • Higher effective ISO
  • $850
  • APS-C
  • In-Camera Image Stabilization
  • Fast startup
Pentax K-3
Pentax K-r
  • $699
  • APS-C
  • Focus peaking
  • Higher effective ISO
  • $850
  • APS-C
  • Less expensive
  • Bigger pixels

Compared to Nikon D7100

Nikon D3100
Nikon D7100
  • $700
  • APS-C
  • Bigger pixels
  • Lighter weight
  • $695
  • APS-C
  • Fast startup
  • Higher effective ISO
Pentax K-3
Nikon D7100
  • $699
  • APS-C
  • Focus peaking
  • In-Camera Image Stabilization
  • $695
  • APS-C
  • Fast startup
  • Longer stills battery life

Compared to Nikon D7200

Nikon D3100
Nikon D7200
  • $700
  • APS-C
  • Bigger pixels
  • Lighter weight
  • $1043
  • APS-C
  • Built-in Wi-Fi
  • NFC
Pentax K-3
Nikon D7200
  • $699
  • APS-C
  • Focus peaking
  • In-Camera Image Stabilization
  • $1043
  • APS-C
  • Fast startup
  • Built-in Wi-Fi
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