Nikon D300 Optics

Zoom
Excellent performance from the newly-announced 24-70mm lens.

The Nikon AF-S 24-70mm f/2.8G ED lens was announced at the same time as the Nikon D300 and D3 digital SLRs were. It almost certainly won't be a "kit" lens for the D300, but we thought readers would be interested in some sample images from this latest example of Nikon's optical prowess. Along with the 14-24mm f/2.8 lens that was announced at the same time, Nikon aims to deliver prime-lens quality with zoom-lens flexibility. As of this writing, we haven't completed our DxO Analyzer evaluation of these lenses, but they certainly appear to deliver impressive quality.

With an equivalent focal length range from 36 to 105mm on the D300, the 24-70mm covers a useful range from moderate wide angle to short telephoto, with a fast, constant f/2.8 aperture. Results were very good at 24mm, with minimal corner softness and strong detail throughout the frame. Coma distortion in the trees is very low, with very little chromatic aberration visible in the corners and edges (see the CA test results below to find out why). Results are also very good at the 70mm setting as well, with no signs of visible coma distortion or chromatic aberration. All in all, a great performance from this new lens.

Distortion
Low barrel distortion at wide angle and low pincushion distortion at telephoto as well.

This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide angle) or inward (like a pincushion -- usually at telephoto). The Nikon 24-70mm lens produced about 0.3% barrel distortion at full wide angle, which is much lower than average. At the 70mm telephoto end, barrel distortion was just under 0.1%; also below average. An excellent performance.

Chromatic aberration
Virtually no chromatic aberration in JPEGs, as the D300 automatically applies C.A. reduction during JPEG processing. Moderate at wide angle when shooting NEFs.

Chromatic aberration is extremely low, almost non existent at both wide angle and full telephoto. This isn't really a surprise though, as the D300 (and D3) remove CA while processing JPEGs. Dave reported on this when he attended the Tokyo rollout for the D300 and D3, but this is the first opportunity we've had to get hands-on with the technology, to see how well it worked.

Below are crops from RAW files converted through Adobe Camera RAW, with no CA correction applied. (Properly treating the D300's RAW files as exactly that (raw, unprocessed recordings of the actual sensor data), Nikon only applies CA correction to the camera-generated JPEGs.)

As you can see from the wide angle RAW crops above, the D300 does a very good job at removing CA from JPEGs (compare to the previous set of wide angle crops). In the uncorrected wide-angle image, the CA is pretty noticeable, but in the corrected version, the coloration is almost invisible. If you look carefully, you can see very slight tinges of color around the target elements in the corrected image, but keep in mind that these are 200% magnifications of 12-megapixel files. Depending on the pixel pitch of your monitor, this is roughly equivalent to squinting at a print roughly 100 inches (~2.6 meters) wide. Very impressive, particularly considering that the camera is figuring this all out on the fly (that is, without the benefit of any pre-recorded lens information) at up to 8 frames/second. (When shooting with the optional battery grip, maximum frame rate is 6 frames/second with the internal battery.)

As it turns out there wasn't much CA to remove from the telephoto RAW file, so the improvement is not as dramatic there.

Corner Sharpness
Minor softening in the corners of the frame with the 24-70mm lens.

The Nikkor 24-70mm lens produced moderately soft corners at wide angle, with the lower right corner being the softest on our sample, but the softening didn't extend very far into the frame at all, so the net effect was really quite minimal. At full telephoto, the corners were only slightly softer than the center of the frame. Again, very good performance.