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

Please note that for this comparison we converted the E-620 RAW files in Capture One (using the default settings). This is because we have reason to believe that Adobe Camera Raw doesn't show the full resolution captured by recent Olympus SLRs (Capture One shows visibly more detail).

Pentax K-x (3.0 MB, 12.3 MP) Canon EOS 500D (3.3 MB, 15.1 MP)
Nikon D5000 (2.6 MB; 12.3 MP) Olympus E-620 (4.1 MB, 12.3 MP)

Pentax K-x Canon EOS 500D
Nikon D5000 Olympus E-620

Pentax K-x Canon EOS 500D
Nikon D5000 Olympus E-620

Pentax K-x Canon EOS 500D
Nikon D5000 Olympus E-620

Measurable results

Camera Measurement
Pentax K-x Horizontal LPH 2350  * 2800 
Vertical LPH 2400  * 3600 
Canon EOS 500D Horizontal LPH 2400  * 3300 
Vertical LPH 2350  * 3200 
Nikon D5000 Horizontal LPH 2400  3200 
Vertical LPH 2350  3200 
Olympus E-620 Horizontal LPH 2250  2650 
Vertical LPH 2250  2650 

* 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)

The resolution figures of all camera increase when shooting RAW but some gain more than others. Both the Nikon and Pentax improve significantly and in terms of absolute resolution almost catch up with the Canon EOS 500D. All cameras, apart form the Olympus E-620, show quite significant moire and artifacts, but this will almost certainly be a non-issue if you photograph scenes other than resolution charts.