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
Canon EOS 7D (4.7MB, 18 MP) Canon EOS 50D (4.0 MB, 15.1 MP)
Nikon D300s (3.2 MB, 12 MP) Pentax K7 (3.6 MB, 14.5 MP)

Canon EOS 7D Canon EOS 50D
Nikon D300s Pentax K7

Canon EOS 7D Canon EOS 50D
Nikon D300s Pentax K7

Canon EOS 7D Canon EOS 50D
Nikon D300s Pentax K7

Measurable results

Camera Measurement
Absolute
resolution
Extinction
resolution
Canon EOS 7D Horizontal LPH 2500  * 3800 
Vertical LPH 2500  * 3900 
Canon EOS 50D Horizontal LPH 2450  * 3300 
Vertical LPH 2350  * 3300 
Nikon D300s Horizontal LPH 2300  3200 
Vertical LPH 2250  3200 
Pentax K7 Horizontal LPH 2450  * 3150 
Vertical LPH 2400  * 3400 

* Moiré 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)

Shooting in RAW and using Adobe ACR to process the images increases the measured resolution on all four cameras but the difference is less obvious on the 7D than on the competitors. Nevertheless, while the absolute resolution remains almost unchanged, extinction resolution is increased which improves the rendering of very fine detail in an image.