Resolution Chart Comparison (Raw)

Shots here are of our 'version two' resolution chart which provides for measurement of resolution up to 4000 LPH (Lines Per Picture Height). A value of 20 equates to 2000 lines per picture height. For each camera the relevant prime lens was used. The chart is shot at a full range of apertures and the sharpest image selected. Studio light, cameras set to aperture priority (optimum aperture selected), image parameters default. Exposure compensation set to deliver approximately 80% luminance of white area.

For a (more) level playing field we also convert our resolution tests using Adobe Camera RAW. Because Adobe Camera RAW applies different levels of sharpening to different cameras (this confirmed) we had to use the following workflow for these conversions:

  • Load RAW file into Adobe Camera RAW (Auto mode disabled)
  • Set Sharpness to 0 (all other settings default)
  • Open file to Photoshop
  • Apply a Unsharp mask: 80%, Radius 1.0, Threshold 0
  • Save as a TIFF (for cropping) and as a JPEG quality 11 for download
Sony Alpha 550 (3.1MB, 14.2 MP) Canon EOS 500D (4.4MB, 15.1 MP)
Nikon D5000 (3.5 MB; 12.3 MP) Pentax K7 (3.6 MB, 14.5 MP)

Sony Alpha 550 Canon EOS 500D
Nikon D5000 Pentax K7

Sony Alpha 550 Canon EOS 500D
Nikon D5000 Pentax K7

Sony Alpha 550 Canon EOS 500D
Nikon D5000 Pentax K7

Measurable results

Camera Measurement
Sony Alpha 550 Horizontal LPH 2300 2500
Vertical LPH 2350 2500
Canon EOS 500D Horizontal LPH 2400  * 3300 
Vertical LPH 2350  * 3200 
Nikon D5000 Horizontal LPH 2400  * 3200 
Vertical LPH 2350  * 3200 
Pentax K7 Horizontal LPH 2450  * 3150 
Vertical LPH 2400  * 3400 

* Moire is visible
+ Chart maximum
LPH Lines per Picture Height (to allow for different aspect ratios the measurement is the same for horizontal and vertical)
Absolute resolution Point at which all lines of a resolution bar are still visible and defined, beyond this resolution loss of detail occurs (below Nyquist frequency).
Extinction resolution Detail beyond camera's definition (becomes aliased)

Unlike the other cameras here the Alpha 550 doesn't gain much at all resolution-wise when shooting raw - certainly not with Adobe Camera Raw or Sony's own converter. As we saw earlier you can get a touch (and I really do mean a touch) more resolution with other, less common raw converters.