The Nikon 10-24mm and 12-24mm lenses are intended for use with the APS-C size sensor cameras such as the D40, D90 and the D300. They are targeted toward semi-professionals. As is typical of this type of lens, both show distortion on the outer edges that is more noticeable with large apertures. Both lenses are very good for close-up photography work or any instance where you need a wide angle of view.
Zoom Mechanism
The zoom mechanism on the 10-24mm lens moves in and out of the lens housing as you change the focal length. If the end of the lens hits anything while at extended zoom, the optics may be damaged. The 12-24mm lens uses an internal-focus design. The length of the lens doesn't change as it zooms from 12 to 24 mm, making it less susceptible to damage.
Image Distortion
In a perfect lens, a photograph of a straight line would appear as a straight line. This is very difficult to create with any lens and even harder to achieve in a zoom lens, as the optics change position relative to each other. The lens creates either a bending out of the line away from the center of the lens, called barrel distortion, or a bending of the line toward the center of the lens, called pincushion distortion.
Testing of the lenses by photozone.de and others indicates that the distortion of the 10-24mm lens is roughly equal to the 12-24mm lens. At wider angles of view, the 10-24mm lens has a barrel distortion at 10mm of 3.1 percent. As the magnification increases, distortion drops off rapidly, changing to a pincushion distortion. At 24mm, it is a pincushion distortion of 0.637 percent. On the 12-24mm lens, the barrel distortion is 1.71 percent at 12mm. It drops off rapidly and ends with a pincushion distortion of 0.572 percent at 24mm.
Chromatic Aberrations
Lens designers go to a great deal of trouble to minimize chromatic aberration. They choose lens materials and coatings to ensure that light of different colors will bend by the same amount as it progresses through the optics. This task is harder on zoom lenses since the glass in the optics change their relative position to each other as the lens magnification increases or decreases. The effect appears as a slight halo around high-contrast areas in the lens. Chromatic aberration is well controlled in both lenses. It is worst at the low end of the magnification but is only about 1.6 pixels.
Vignetting
Vignetting in a lens appears as a drop-off in the amount of light passing through the lens. The image will appear darker as the distance increases from the center of the lens. It is measured in terms of EV (exposure value). A drop of one EV is equivalent to losing half the light passing through the area of the lens. Since less of the lens area is used as you decrease the aperture, it is more noticeable when the aperture is wide open at f/4 or f/3.5. Since these lenses are designed for APS-C cameras, this effect is more noticeable than if you were using a full frame lens. The vignetting is reduced significantly at f/5 and is very good above f/8.
Resolution
The resolution of a lens is a measure of how sharp the detail presented to the sensor would be and how fine the detail in the image would be. Typically, the resolution in the center of the image is better than the edges. As is typical in zoom lenses, the resolution is worse at a minimum zoom and improves as the magnification increases. The testing by photozone.de indicates that the 12-24mm's resolution at minimum zoom and wide-open aperture is poor but improves rapidly as the zoom level increases. The 10-24mm lens shows a decrease in resolution at 18mm with the aperture wide open.
Tags: 10-24mm lens, pincushion distortion, 12-24mm lens, barrel distortion, center lens, distortion percent