Group Test: 24-120mm Extended Standard Zooms - Verdict

Verdict

This review has looked at lenses that nominally cover a 24-120mm zoom range. Sigma's lens is an 18-125mm but has a shorter minimum focal length because it is for use with APS-C sensors only whereas Canon's and Nikon's lenses, which cover 28-135mm and 24-120mm respectively, also accommodate full-frame sensors. Nevertheless, Sigma's lens achieves a 7x zoom range, which the most expansive in this test.

Olympus's lens may seem out of place with a 14-54mm zoom range but the format's 22mm standard focal length means that the zoom covers from 0.6x to 2.5x the standard focal length. As it happens this is very similar to the effect of a full-frame 24-120mm zoom, which covers from 0.6x to 2.8x its own standard focal length.

As noted earlier, a complication arises when the same 24-120mm lens (or a slightly longer 28-135mm lens) is used in combination with an APS-C sensor. In this case the equivalent range is from 0.9x to 4.4x the standard focal length (or 1x to 5x for the longer zoom) so a lens that covers both sides of the standard focal length for a full-frame camera will be an (almost) entirely telephoto zoom when fitted to an APS-C camera.

Having established that the four lenses tested here are both similar (if used on their native formats) and different (when the full-frame lenses are fitted to APS-C bodies) it is time to summarise the results and draw some conclusions.

The four lenses are all compact designs that are affordably priced, although Sigma's lens is the bargain and Nikon's is the most costly. Nikon could say that its lens combines the best of all the others because only two of the other three feature image stabilisation technology of some sort; a different two of the other three sport aspherical profiles and yet another two-from-three selection provide full manual intervention in AF mode. Only Nikon's lens does everything.

The problem is that Nikon's lens doesn't produce the best results despite being packed to the gunnels with technology. First place goes to Canon's lens, although this ranking is made with the important proviso that the EF 28-135mm zoom was tested only on an APS-C body and the possibility of slight full-frame vignetting, spotted with the Nikkor, cannot be discounted. Even so, on the evidence presented here there is little of substance that can be held against Canon's zoom.

Sigma's lens is the only one that is available to fit multiple mounts and is therefore likely to have wider appeal than the others. Optically it performs well under most conditions although greater wide-aperture consistent would be preferred. In addition, the Sigma's fall-off in MTF beyond f/22 is even more severe than is often the case. It seems pointless for lens manufacturers to offer tiny minimum apertures when the MTF figures have fallen to 0.15 cycles-per-pixel or even lower but still they do. That said, it is not so much optical quality as ergonomics that really let the Sigma down.

Lastly there is the Olympus lens, which has been tested here for the second time following an appearance last year amidst a clutch of Canon and Olympus standard zooms. On the previous occasion it scored 90% and was criticised only for slight chromatic aberration: the same problem has also been noted here but to a higher extent, witnessed by weaker wide-aperture MTF data and resulting in a minor deflation of its score.

This raises the potentially thorny issue of consistency in the results published within these tests. It should be noted that repeats are performed within each test, especially if unexpected results are obtained, but the tests or not duplicated en masse. The results that are reported are consistent within their own data sets but that does not rule out long-term variation. This could be caused by experimental errors, degradation of the lens during prolonged testing by several magazines or genuine differences between multiple samples of the same lens.

Whatever the cause of such variations they should always be slight unless there is a rogue sample amongst the lenses. This means that the trends reported should be valid in general although the details of each trend may be specific to the test in hand.

Returning to the four lenses that have been evaluated here, it is clear that they are all very competent and affordable (although to slightly different degrees). They are also all compact designs, which will help for lenses that could serve as the default choice for many picture-taking occasions. In fact any one of these lenses might be all that you will need to cover the majority of your everyday photographic needs.

See tests of these lenses

• Canon EF 28-135mm f/3.5-5.6 IS Macro USM review
• Nikon AF-S VR Zoom-Nikkor 24-120mm f/3.5-5.6G IF-ED review
• Olympus Zuiko Digital 14-54mm f/2.8-3.5 II review
• Sigma 18-125mm f/3.8-5.6 DC OS HSM review