Resolution Chart Comparison
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.
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| Nikon D90 (3.8 MB, 12.2 MP) | Nikon D80 (2.7 MB, 10.0 MP) |
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| Canon EOS 450D (2.6 MB, 12.2 MP) | Pentax K20D (8.6 MB, 14.5 MP) |
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| Nikon D90 | Nikon D80 |
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| Canon EOS 450D | Pentax K20D |
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| Nikon D90 | Nikon D80 |
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| Canon EOS 450D | Pentax K20D |
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| Nikon D90 | Nikon D80 |
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| Canon EOS 450D | Pentax K20D |
Measurable results
| Camera | Measurement | Absolute resolution |
Extinction resolution |
|---|---|---|---|
| Nikon D90 | Horizontal LPH | 2200 | 2450 |
| Vertical LPH | 2150 | 2450 | |
| Nikon D80 | Horizontal LPH | 2200 | 2300 |
| Vertical LPH | 1800 | 2300 | |
| Canon EOS 450D | Horizontal LPH | 2300 | * 2500 |
| Vertical LPH | 2200 | * 2500 | |
| Pentax K20D | Horizontal LPH | 2250 | * 2400 |
| Vertical LPH | 2250 | * 2400 |
| * | 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 D90's output may not appear as sharp but it's actually capturing a not-dissimilar amount of detail. It's also noticeable that it shows much less of the moiré that is clearly visible as the Pentax and Canon approach extinction resolution. It certainly puts any concerns about resolution into perspective - it may not quite have the 450D or D300's pixel-detail in side-by-side comparisons but the difference, even when faced with a resolution test chart that is more demanding than any real-world situation, is negligible.
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