Coverage, wide angle with Nikon D2X

All three lenses on test claim the same 18-200mm focal length, but it's always worth putting this to the test. To compare actual coverage we shot the same scene with each lens within a few moments of each other; the camera was mounted on a tripod to ensure a consistent position. Here the lenses were set to their widest 18mm focal length.

At first glance the three lenses on test appear to deliver identical wide-angle coverage, but look closer and there's subtle differences. The Tamron 18-200mm actually delivered a fractionally wider view at 18mm than the others, followed closely by the Nikkor, and finally the Sigma.

Sigma 18-200mm F3.5-6.3 DC		Nikkor AF-S DX VR 18-200mm 3.5-5.6G IF-ED		Tamron AF18-200mm F3.5-6.3 XR Di-II LD IF
18-200mm at 18mm (27mm equivalent using Nikon D2X)		18-200mm at 18mm (27mm equivalent using Nikon D2X)		18-200mm at 18mm (27mm equivalent using Nikon D2X)

Coverage, telephoto with Nikon D2X

Next up came the telephoto-end of each lens. Again to compare actual coverage we shot the same scene with each lens within a few moments of each other; the camera was mounted on a tripod to ensure a consistent position. Here the lenses were set to their longest 200mm focal length.

Here all three lenses performed similarly, although upon close examination, the Nikkor's field was fractionally tighter than the others. In practice though it's fair to say all three lenses deliver essentially the same field of views.

Sigma 18-200mm F3.5-6.3 DC		Nikkor AF-S DX VR 18-200mm 3.5-5.6G IF-ED		Tamron AF18-200mm F3.5-6.3 XR Di-II LD IF
18-200mm at 200mm (300mm equivalent using Nikon D2X)		18-200mm at 200mm (300mm equivalent using Nikon D2X)		18-200mm at 200mm (300mm equivalent using Nikon D2X)

Note: both the Sigma and Tamron lenses were fitted with zoom lock switches to prevent their barrels from extending beyond the 18mm focal length while in transit. That said neither barrels of the models on test could be described as loose, and it was possible to zoom-in to 200mm on both, point vertically upwards and not suffer from any creep back down. The Nikkor lens didn't have a lock, but could be pointed up or down without suffering from discernable creep.