• 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-PM2

  • Larger sensor
    APS-C vs 4/3
    More sensor area. Bigger is (generally) better.
  • Eye-level viewfinder
    Eye-level vs Rear display only
    You'll be able to frame photos even when the sun is out
  • Bigger pixels
    ~ 5.01 vs 3.75 microns
    Better low-light and dynamic range (all else equal)
  • Fast startup
    ~0.40 vs 0.7 sec
    Faster startup lets you catch the moment
  • Longer stills battery life
    More info 550 vs 360 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
  • Bigger JPEG buffer
    100 vs 16 shots
    Take more JPEG shots before waiting (burst mode)

Olympus E-PM2 advantages over Nikon D3100

  • Less expensive
    $500 vs $700 (MSRP)
    Save money for lenses or accessories
  • 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
  • Thinner
    33 mm vs 74 mm
    Thinner
  • Lighter weight
    384g vs 777g
    Lighter weight
  • More dots on screen
    461k vs 230k dots
    Can mean greater resolution or a brighter screen
  • Longer exposure
    60 vs 30 sec
    Long exposures for night shots
  • Faster JPEG shooting
    7.9 fps vs 2.9 fps
    Faster JPEG shooting (burst mode)
  • Higher extended ISO
    25600 vs 12800 ISO
    Higher extended ISO can give more low-light flexibility

Similarities

Common Strengths

  • 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

  • Focus peaking
    Neither provide
    Your camera will highlight what's in focus
  • 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
  • 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
  • Top deck display
    Neither provide
    Check settings with a screen on top of the camera
  • External Mic Jack
    Neither provide
    Improved sound fidelity when shooting video
  • 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-PM2

Review Excerpt

  • Super compact and lightweight; Excellent image and print quality that rivals much more expensive CSCs and DSLRs; Solid low-light (high ISO) performance; Touchscreen LCD responsive and useful once you get used to it; Speedy and accurate AF on still subjects; Tons of advanced shooting features and customizing options.

  • Maddening menu system; No physical Mode dial; Motion AF not quite up to par; Mediocre HD video quality; No built-in flash (but a small external flash is included).

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
Olympus E-PM2
Sony DSLR-A380
  • $1599
  • 4/3
  • Lens selection
  • Less expensive
  • $849
  • APS-C
  • Larger sensor
  • Eye-level viewfinder

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-PM2
Sony A33
  • $1599
  • 4/3
  • Lens selection
  • Less expensive
  • $540
  • APS-C
  • Larger sensor
  • Eye-level viewfinder

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-PM2
Pentax K-r
  • $1599
  • 4/3
  • Less expensive
  • Touchscreen
  • $850
  • APS-C
  • Larger sensor
  • Eye-level viewfinder

Compared to Panasonic GF3

Nikon D3100
Panasonic GF3
  • $700
  • APS-C
  • Larger sensor
  • Eye-level viewfinder
  • $675
  • 4/3
  • Touchscreen
  • Thinner
Olympus E-PM2
Panasonic GF3
  • $1599
  • 4/3
  • Less expensive
  • In-Camera Image Stabilization
  • $675
  • 4/3
  • Bigger pixels
  • Internal flash

Compared to Panasonic GM5

Nikon D3100
Panasonic GM5
  • $700
  • APS-C
  • Larger sensor
  • Less expensive
  • $898
  • 4/3
  • Focus peaking
  • Touchscreen
Olympus E-PM2
Panasonic GM5
  • $1599
  • 4/3
  • Less expensive
  • In-Camera Image Stabilization
  • $898
  • 4/3
  • Focus peaking
  • Eye-level viewfinder
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