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
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| Nikon D300s (3.2 MB, 12 MP) | Canon EOS 7D (4.7MB, 18 MP) |
|---|---|
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| Pentax K-7 (3.6 MB, 14.5 MP) | Canon EOS 50D (4.0 MB, 15.1 MP) |
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| Nikon D300S | Canon EOS 7D |
|---|---|
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| Pentax K-7 | Canon EOS 50D |
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| Nikon D300S | Canon EOS 7D |
|---|---|
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| Pentax K-7 | Canon EOS 50D |
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| Nikon D300S | Canon EOS 7D |
|---|---|
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| Pentax K-7 | Canon EOS 50D |
Measurable results
| Camera | Measurement | Absolute resolution |
Extinction resolution |
|---|---|---|---|
| Nikon D300S | Horizontal LPH | 2300 | 3200 |
| Vertical LPH | 2250 | 3200 | |
| Canon EOS 7D | Horizontal LPH | 2500 | * 3800 |
| Vertical LPH | 2500 | * 3900 | |
| Pentax K7 | Horizontal LPH | 2450 | * 3150 |
| Vertical LPH | 2400 | * 3400 | |
| Canon EOS 50D | Horizontal LPH | 2450 | * 3300 |
| Vertical LPH | 2350 | * 3300 |
| * | 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 alias ed) |
Shooting in RAW and using Adobe ACR to process the images increases the measured resolution on all four cameras and also brings them all to a similar level. Although the D300S has the lowest nominal resolution (pixel count), it isn't far behind the others in terms of what it can actually resolve. As we've already seen, still better results are possible from Nikon's own software, so anyone worried that a 12 megapixel camera can't quite cut it can allay much of this fear by processing from RAW.
