• 0.98 inch 285.7mm2
  • 4.7 megapixels
  • ISO 100 - 1600
  • APS-C 369.7mm2
  • 16.1 megapixels
  • ISO 100 - 16,000

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Differences

Sigma SD15 advantages over Sony A57

  • Bigger pixels
    ~ 7.84 vs 4.82 microns
    Better low-light and dynamic range (all else equal)
  • Top deck display
    Yes vs No
    Check settings with a screen on top of the camera
  • Doesn't require an AA filter
    Yes vs No
    A unique sensor design provides sharp photos without moiré

Sony A57 advantages over Sigma SD15

  • Lens selection
    Good vs Limited
    Better lens selection gives you more options
  • Focus peaking
    Peaker vs Non-peaker
    Your camera will highlight what's in focus
  • Larger sensor
    APS-C vs 0.98 inch
    More sensor area. Bigger is (generally) better.
  • In-Camera Image Stabilization
    Yes vs No
    Reduces the effects of camera shake at slower shutter speeds
  • In-camera panoramas
    Yes vs No
    Stitches multiple shots into a panoramic photo
  • Tiltable Screen
    Tiltable vs Fixed
    Tilt the screen for shooting flexbility
  • Longer stills battery life
    More info 550 vs 250 shots
    Capture more photos
  • More cross-type AF points
    3 vs 1
    Cross-type AF points improve autofocus performance
  • HDMI out
    HDMI out vs None
    Use HDMI output to monitor or review video
  • Shoots 24p video
    Yes vs No
    Gives your movies a big-screen feel
  • More dots on screen
    922k vs 460k dots
    Can mean greater resolution or a brighter screen
  • Shoots 1080p video
    Yes vs No
    You'll want this if you shoot video
  • More viewfinder magnification
    0.69x vs 0.53x
    Get a bigger view of the scene through the eye-level viewfinder
  • More pixels
    16.1 vs 4.7 megapixels
    Higher resolution photos
  • Shoots 60p video
    Yes vs No
    A faster framerate can give you more editing options
  • More AF points
    15 vs 5
    More AF points improve autofocus
  • Faster JPEG shooting
    10.0 fps vs 3.0 fps
    Faster JPEG shooting (burst mode)
  • Higher extended ISO
    25600 vs 3200 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
  • Hot shoe
    Both provide
    Off-camera flashes open new possibilities
  • Bulb shutter
    Both provide
    Hold the shutter open manually for long exposures

Common Weaknesses

  • Touchscreen
    Neither provide
    Interact with your camera just like your smartphone
  • 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
  • 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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Review Excerpt

The Competition

Compared to Olympus E30

Sigma SD15
Olympus E30
  • $1500
  • 0.98 inch
  • Larger sensor
  • Bigger pixels
  • $1299
  • 4/3
  • Lens selection
  • In-Camera Image Stabilization
Sony A57
Olympus E30
  • $800
  • APS-C
  • Less expensive
  • Focus peaking
  • $1299
  • 4/3
  • Top deck display
  • Higher max flash sync

Compared to Sony DSLR-A330

Sigma SD15
Sony DSLR-A330
  • $1500
  • 0.98 inch
  • Bigger pixels
  • Top deck display
  • $530
  • APS-C
  • Lens selection
  • Larger sensor
Sony A57
Sony DSLR-A330
  • $800
  • APS-C
  • Focus peaking
  • In-camera panoramas
  • $530
  • APS-C
  • Less expensive
  • Bigger pixels

Compared to Olympus E-5

Sigma SD15
Olympus E-5
  • $1500
  • 0.98 inch
  • Larger sensor
  • Bigger pixels
  • $1700
  • 4/3
  • Lens selection
  • In-Camera Image Stabilization
Sony A57
Olympus E-5
  • $800
  • APS-C
  • Less expensive
  • Focus peaking
  • $1700
  • 4/3
  • Longer stills battery life
  • Top deck display

Compared to Nikon D5100

Sigma SD15
Nikon D5100
  • $1500
  • 0.98 inch
  • Bigger pixels
  • Top deck display
  • $650
  • APS-C
  • Lens selection
  • Larger sensor
Sony A57
Nikon D5100
  • $800
  • APS-C
  • Focus peaking
  • In-Camera Image Stabilization
  • $650
  • APS-C
  • Lens selection
  • Tilt-swivel screen

Compared to Pentax K-5 IIs

Sigma SD15
Pentax K-5 IIs
  • $1500
  • 0.98 inch
  • Bigger pixels
  • Doesn't require an AA filter
  • $497
  • APS-C
  • Lens selection
  • Larger sensor
Sony A57
Pentax K-5 IIs
  • $800
  • APS-C
  • Less expensive
  • Focus peaking
  • $497
  • APS-C
  • Lens selection
  • Higher effective ISO
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