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.

Nikon D300 (3.3 KB; 12 MP) Canon EOS 40D (2.6 MB, 10 MP)
Sony DSLR-A700 (2.6 MB, 12 MP) Olympus E-3 (3.3 MB; 10 MP)

Nikon D300 Canon EOS 40D
Sony DSLR-A700 Olympus E-3

Nikon D300 Canon EOS 40D
Sony DSLR-A700 Olympus E-3

Nikon D300 Canon EOS 40D
Sony DSLR-A700 Olympus E-3

Measurable results

Camera Measurement
Nikon D300 Horizontal LPH 2200  2600 
Vertical LPH 2100  2600 
Canon EOS 40D Horizontal LPH 2100  2300 
Vertical LPH 1800  2300 
Sony DSLR-A700 Horizontal LPH * 2200  2900 
Vertical LPH 2100  2800 
Olympus E-3 Horizontal LPH * 2100  2400 
Vertical LPH * 1800  2200 

* Moire 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)

As you can see from the figures (and crops) above there really is very little difference between ten and twelve megapixels, however the sensor design (anti-alias filter strength), imaging pipeline (demosaicing, sharpening) have a much more significant effect that megapixels alone. The D300's image is the cleanest here with no noticeable moire and almost invisible sharpening artifacts. The DSLR-A700 delivers as much absolute resolution and manages to delve a bit deeper beyond nyquist (to extinction resolution) but seemingly at the expense of some visible moire.