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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

Because Adobe Camera Raw doesn't currently render the same level of detail as resolved by the camera's JPEG engine, we've taken the unusual step of using Phase One's Capture One. Again we've minimized sharpening and applied the same unsharp mask in Photoshop.

Sigma DP2 (2.3 MB, 4.69x3 MP) Olympus E-P1 (5.4 MB, 12.3 MP)
Ricoh GRD III (3.3 MB; 10.0 MP) Sony DSLR A330 (2.5 MB, 10.2 MP)

Sigma DP2 Olympus E-P1
Ricoh GRD III Sony DSLR A330

Sigma DP2 Olympus E-P1
Ricoh GRD III Sony DSLR A330

Sigma DP2 Olympus E-P1
Ricoh GRD III Sony DSLR A330

Measurable results

Camera Measurement
Absolute
resolution
Extinction
resolution
Sigma DP2 Horizontal LPH * 1500  * 2650 
Vertical LPH * 1450  * 2650 
Olympus E-P1 Horizontal LPH 2200  * 2750 
Vertical LPH 2150  * 2700 
Ricoh GR Digital III Horizontal LPH 1900  * 2600 
Vertical LPH 2000  * 2600 
Sony A330 Horizontal LPH 1800  * 2200 
Vertical LPH 1800  * 2200 

* 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)

ACR does little to pull more resolution out of the RAW files, which suggests the camera's JPEG engine is doing a reasonable job. Given that the JPEG is representing detail well beyond Nyquist (the theoretical maximum), it's no surprise that there's little more to be gained in RAW.

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