To measure and compare the Nikon D40's kit lens geometric distortion we photographed a test chart consisting of a grid pattern, using it and a number of rival models.

Here are the results for each camera with their kit lenses at their widest focal length; where possible, the aperture was closed.

The images were analysed with Imatest using 5th Order line calculation and the full areas presented here at a reduced resolution.

The image left was taken with the Nikon D40 using the DX 18-55mm II kit lens zoomed-out to 18mm. Barrel distortion was measured at 3.73% which is more pronounced than the other lenses below, although not a great deal more than the Canon 400D / XTi's kit lens.

DX 18-55mm II at 18mm f8
Distortion: 3.73% barrel

Canon 400D / XTi Using EF-S 18-55mm		Canon PowerShot G7		Olympus E-400 Using ZD 14-42mm
EF-S 18-55mm at 18mm f8 Distortion: 3.35% barrel		7.4-44.4mm at 7.4mm Distortion: 3.34% barrel		ZD 14-42mm at 14mm f8 Distortion: 2.97% barrel

Nikon D40 telephoto geometry comparison

		To measure and compare the Nikon D40's kit lens geometric distortion we photographed a test chart consisting of a grid pattern, using it and a number of rival models. Here are the results for each camera with their kit lenses at their longest focal length; where possible, the aperture was closed. The images were analysed with Imatest using 5th Order line calculation and the full areas presented here at a reduced resolution.
DX 18-55mm II at 55mm f8 Distortion: 0.21% barrel

Canon 400D / XTi Using EF-S 18-55mm		Canon PowerShot G7		Olympus E-400 Using ZD 14-42mm
EF-S 18-55mm EF-S at 55mm f8 Distortion: 0.389% pincushion		7.4-44.4mm at 44.4mm f5.6 Distortion: 0.28% pincushion		ZD 14-42mm at 42mm f8 Distortion: 0.21% barrel