Nikkor AF-S 24-70mm f/2.8G ED Review / Quick Test Report


11/11/2007 © by Klaus Schroiff
Lens kindly provided by Gustel Schrempp!
Introduction

Newly designed full format lenses weren't overly popular on the Nikon side of life lately but the release of the new Nikon D3 seems to have shifted the priorities again. The Nikkor AF-S 24-70mm f/2.8G ED is the first of a whole series of new professional grade full format lenses. It is obviously a replacement for the "old" AF-S 28-70mm f/2.8 ED D (released in 1999). Apart from the highly useful extension at the wide-end of the zoom range the new lens features a reduced minimum focus distance and Nikon's latest development in coating technology, Nano Crystal Coat, which is supposed to suppress internal reflections and ghostings. Typical for all new Nikkors it is a G-type lens so it doesn't offer a dedicated aperture ring anymore.
Eventually you'll see full format lens tests here at photozone but the current priority is still on APS-C format sensors and within this scope the field of view of the AF-S 24-70mm f/2.8G ED is equivalent to a classic "36-105mm" lens . The lens may loose quite a bit of its wide-angle appeal here but it is certainly more usable as a standard zoom than the old AF-S 28-70mm f/2.8 IF-ED D (equivalent to "42-105mm").

Over the decades Nikon earned a reputation of manufacturing lenses with a higher than average build quality and the AF-S 24-70mm f/2.8G ED does certainly deliver here. It is a truly professional grade zoom lens thanks to a tough metal lens body and smoothly operating control rings. As you may notice in the product shots below the lens (its inner tube) extends significantly when zooming towards the wide end of the zoom range and a tiny bit towards 70mm. The shortest physical length is reached around the 50mm setting. This may sound odd but it is actually quite typical for fast Nikon (and Canon) standard zooms. The supplied petal shaped hood can be attached to the outer lens barrel thus providing a near-optimal protection at all focal length. The physical length with attached hood is constant.


Thanks to an IF (internal focusing) design the front element does not rotate so using a polarizer is no problem (unless you attach the lens hood). Like all modern Nikkors it features a silent-wave (ultrasonic) AF motor providing extremely fast and near-silent AF operations. The AF accuracy of the tested sample was exceptional.
SpecificationsOptical construction15 elements in 11 groups inc. 3x ED elements, 3x aspherical elements and 1x Nano Crystal CoatNumber of aperture blades9 (rounded)min. focus distance0.39m @ 35-50mm (max. magnification ratio 1:3.7)Dimensions83x133mmWeight900gFilter size77mm (non-rotating)HoodNikon HB-40 (supplied), petal-shapedOther featuresRubber mount seal
Distortions

Similar to its predecessor the AF-S 24-70mm ED exhibits a very slight degree (~1.1%) of barrel distortions at 24mm decreasing to marginal pincushion distortions beyond. This is exceptional for a standard zoom lens (on an APS-C DSLR).
Please note that some users reported that the lens seems to produce a quite hefty amount of barrel distortions at 24mm when used on a full format DSLR.

Move the mouse cursor over the focal length text marks below to observe the respective distortions 24mm 40mm 70mm

The chart above has a real-world size of about 120x80cm.

Vignetting

Thanks to its full frame design the Nikkor AF-S 24-70mm ED shows very little vignetting on the D200. At 24mm and 40mm the issue is already negligible at wide-open aperture. The problem increases marginally towards 70mm but it is still not really field relevant here even at f/2.8.

MTF (resolution)

The AF-S 24-70mm f/2.8 ED produced very good to exceptional resolution figures in the MTF lab. The center resolution is excellent to outstanding throughout of the tested aperture range. At 24mm and 40mm the center resolution is likely to match and possibly even exceed a 10mp sensor resolution and that's also at f/2.8 which is quite amazing. The borders aren't quite as impressive but still very good at large apertures and excellent at medium aperture settings. There's a slight drop is quality at 70mm but even here the lens is darn good. On the downside the field curvature is fairly pronounced at 24mm so you need to stop down sufficiently when shooting flat objects at this setting - otherwise your background will run out-of-focus (depth-of-field). The tested sample showed a very good centering quality.
Below is a simplified summary of the formal findings. The chart shows in line widths per picture height (LW/PH) which can be taken as a quantity for sharpness. The chart is limited to the visually relevant LW/PH range of [750, 2250]. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations.

Chromatic Aberrations (CAs)

On the average chromatic aberrations (color shadows at harsh contrast transitions) are comparatively low for a standard zoom lens. Unfortunately the CAs were a bit unsymmetrical in the tested sample making it difficult to remove all CA traces via post-processing.

Sample Images

Here're some quick'n dirty sample images taken with the D200 and RAW-converted via ACR. Unfortunately the weather conditions where very unfavorable at the time of the test so I apologize for the rather low quality.
Click on a thumbnail to view the original file (opens in a separate window). Please note that the originals are FULL SIZE (=several megabytes) which requires quite some bandwidth for downloading so please don't waste the limited resources here.
MakeNIKON CORPORATION
ModelNIKON D200ISO Speed200Focal Length24.0mm Exposure Data:f/8.0 @ 1/640sSize2613x3898MakeNIKON CORPORATION
ModelNIKON D200ISO Speed400Focal Length24.0mm Exposure Data:f/8.0 @ 1/800sSize3898x2613MakeNIKON CORPORATION
ModelNIKON D200ISO Speed200Focal Length70.0mm Exposure Data:f/2.8 @ 1/640sSize3898x2613MakeNIKON CORPORATION
ModelNIKON D200ISO Speed200Focal Length62.0mm Exposure Data:f/2.8 @ 1/200sSize2613x3898MakeNIKON CORPORATION
ModelNIKON D200ISO Speed400Focal Length24.0mm Exposure Data:f/2.8 @ 1/250sSize2613x3898MakeNIKON CORPORATION
ModelNIKON D200ISO Speed400Focal Length29.0mm Exposure Data:f/8.0 @ 1/125sSize3898x2613Verdict

The Nikkor AF-S 24-70mm f/2.8G ED exceeds the already very good performance of its predecessor. The center quality is nothing short of outstanding matching or beating the resolution of a 10mp APS-C sensor. The border quality is very good at large aperture increasing to excellent levels at f/5.6-8. However, you've to be careful with the curved focus field at 24mm which can result in out-of-focus background corners! Distortions and vignetting are very low and not really field relevant. Chromatic aberrations are generally well controlled although they could have been somewhat more symmetrical (in the tested sample). The bokeh (out-of-focus blur) is unusually smooth and buttery for a zoom lens with aspherical elements. Please note, however, that 70mm f/2.8 isn't terribly fast on an APS-C DSLR so you've to be fairly close to your main subject in order to produce a pronounced out-of-focus blur. The build quality of the lens is superb and it´s a joy to handle it in the field despite its comparatively hefty size and weight. The high speed and low noise of the silent-wave AF drive is the cream on top of it all. The primary aspect which can spoil the game is, unsurprisingly, the high price point of around 1500€/US$.