• APS-C 355.7mm2
  • 14.2 megapixels
  • ISO 100 - 3200
  • 4/3 224.9mm2
  • 16.1 megapixels
  • ISO 200 - 25,600

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Differences

Nikon D3100 advantages over Olympus E-M1

  • Larger sensor
    APS-C vs 4/3
    More sensor area. Bigger is (generally) better.
  • Bigger pixels
    ~ 5.01 vs 3.75 microns
    Better low-light and dynamic range (all else equal)
  • Fast startup
    ~0.40 vs 0.8 sec
    Faster startup lets you catch the moment
  • Higher effective ISO
    919 vs 757 iso
    Take photos in low light with less noise
  • Longer stills battery life
    More info 550 vs 350 shots
    Capture more photos
  • Internal flash
    Internal flash vs None
    Useful in a pinch for fill flash
  • Shoots 24p video
    Yes vs No
    Gives your movies a big-screen feel
  • Has anti-aliasing filter
    Filter vs No Filter
    Reduces unsightly moiré in photos
  • Bigger JPEG buffer
    100 vs 50 shots
    Take more JPEG shots before waiting (burst mode)

Olympus E-M1 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
  • Touchscreen
    Touch vs No touch
    Interact with your camera just like your smartphone
  • Tiltable Screen
    Tiltable vs Fixed
    Tilt the screen for shooting flexbility
  • Built-in Wi-Fi
    Wi-Fi vs None
    Share your photos wirelessly
  • More dynamic range
    12.7 vs 11.2 evs
    Retain detail in highlight and shadows
  • On-sensor phase detect
    Yes vs No
    Usually improves live view and video AF performance
  • External Mic Jack
    Jack vs No jack
    Improved sound fidelity when shooting video
  • Higher max flash sync
    1/320 vs 1/200 sec
    Reduce the effect of ambient light in flash shots
  • 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
    0.74x vs 0.53x
    Get a bigger view of the scene through the eye-level viewfinder
  • Lacks anti-aliasing filter
    No Filter vs Filter
    Enjoy sharper photos
  • Longer exposure
    60 vs 30 sec
    Long exposures for night shots
  • Faster JPEG shooting
    9.9 fps vs 2.9 fps
    Faster JPEG shooting (burst mode)
  • Faster shutter
    1/16000 vs 1/4000 sec
    Shoot wide open in bright light
  • Higher extended ISO
    25600 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
  • 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
  • In-camera panoramas
    Neither provide
    Stitches multiple shots into a panoramic photo
  • 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
  • Top deck display
    Neither provide
    Check settings with a screen on top of the camera
  • Dual card slots
    Neither provide
    Gives you more storage flexibility
  • Headphone jack
    Neither provide
    Monitor audio recording while you shoot video
  • Slow-motion videos
    Neither provide
    Shoot slow-motion videos

User reviews

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Buy the Olympus E-M1

Review Excerpt

  • Exceptional rugged, weather-proof, professional build; Lightning fast contrast-detect AF, and phase-detect AF that makes Four Thirds lenses far more responsive; Tons of useful physical controls with immense customizability; Arguably the best image quality of any Micro Four Thirds camera we've tested to date; Large, sharp, high-resolution electronic viewfinder; Advanced Wi-Fi capabilities, including remote control shooting in PASM exposure modes.

  • Bigger and heavier than many other compact system cameras; Most expensive Micro Four Thirds camera on the market to date; Menu system and customization options have a steep learning curve; No optical low-pass filter means greater risk of moire; No built-in flash.

The Competition

Compared to Olympus E-M5

Nikon D3100
Olympus E-M5
  • $700
  • APS-C
  • Less expensive
  • Larger sensor
  • $900
  • 4/3
  • In-Camera Image Stabilization
  • Touchscreen
Olympus E-M1
Olympus E-M5
  • $1099
  • 4/3
  • Focus peaking
  • Fast startup
  • $900
  • 4/3
  • Thinner
  • Shoots 60p video

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
Olympus E-M1
Sony DSLR-A380
  • $1099
  • 4/3
  • Lens selection
  • Focus peaking
  • $849
  • APS-C
  • Larger sensor
  • 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
Olympus E-M1
Sony A33
  • $1099
  • 4/3
  • Lens selection
  • Focus peaking
  • $540
  • APS-C
  • Larger sensor
  • 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
Olympus E-M1
Pentax K-r
  • $1099
  • 4/3
  • Focus peaking
  • Touchscreen
  • $850
  • APS-C
  • Larger sensor
  • Bigger pixels

Compared to Panasonic GH3

Nikon D3100
Panasonic GH3
  • $700
  • APS-C
  • Less expensive
  • Larger sensor
  • $798
  • 4/3
  • Tilt-swivel screen
  • Touchscreen
Olympus E-M1
Panasonic GH3
  • $1099
  • 4/3
  • Focus peaking
  • In-Camera Image Stabilization
  • $798
  • 4/3
  • Tilt-swivel screen
  • Longer stills battery life
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