Canon EF-S 18-135mm f/3.5-5.6 STM IS - Review / Test Report
Lens Reviews - Canon EOS (APS-C)

Introduction

Canon produces some of the finest lenses out there but to date their extreme range zoom lenses were hardly stunning. The Canon EF-S 18-200mm f/3.5-5.6 IS is clearly substandard and the EF-S 18-135mm f/3.5-5.6 IS was not without flaws either. Even the mighty full format Canon EF 28-300mm f/3.5-5.6 USM L IS is ... well ... white ... but optically not all that great as well (albeit sufficiently good and certainly tough enough for press work). So let's get ready for the next attempt - the Canon EF-S 18-135mm f/3.5-5.6 STM IS. While the paper-specs look pretty similar to the old EF-S 18-135mm f/3.5-5.6 IS, Canon redesigned the optical construction with a large diameter UD element sitting in the front lens group which is certainly promising. The lens has, obviously, a 7.5x zoom ratio and an equivalent full format range of 29-216mm. As such it can be used for a variety of scenes although the slow max. aperture limits the creative potential a bit. Additionally it features a new AF motor - a "STM" = "stepping motor" which has been optimized for movie shooting.

The build quality of the Canon lens is somewhat better compared to the typical low-end/"budget" class zoom lenses by Canon. The plastic quality is quite decent and the lens feels pretty "tight" in terms of build tolerances. The mount is made of metal. The lens extends when zooming towards the longer focal lengths but there's no wobbling of the inner tubes even at the 135mm setting. Both the zoom and especially the focus ring operate smoothly. Unlike on the predecessor the focus ring does no longer rotate during AF operations - which is a nice value-add from the new STM. The tested sample did not suffer from zoom creeping.

As already mentioned the EF-S 18-135mm f/3.5-5.6 STM IS features a new stepping AF motor (STM). Surprisingly the AF speed is very high and we can confirm that the AF action is much smoother compared to a conventional USM AF motor. AF operations are also basically noiseless. Our test camera is not optimized for STM lenses yet but we'd say that LiveView AF is also better now - certainly more so on brand new DSLRs with explicit STM support such as the EOS 650D.
Typical for most Canon EF lenses, it features an optical image stabilizer which is supposed to offer an equivalent "gain" of up to 4 f-stops. In the real life you should expect somewhat less than that though. The IS is "dynamic" so it switches automatically between static image stabilization and panning for object tracking.

Specifications
Equiv. focal length29-216 mm (full format equivalent)
Equiv. aperturef/5.6-f/9 (full format equivalent, in terms of depth-of-field - not speed)
Optical construction16 elements in 12 groups inc. 1x UD and 1x aspherical elements
Number of aperture blades7 (circular)
min. focus distance0.39 m (max. magnification ratio ~1:3.6 @ 135 mm)
Dimensions76.6 x 96 mm
Weight480 g
Filter size67 mm (non-rotating)
Hoodoptional, petal-shaped, bayonet mount
Other featuresIS (Image-Stabilizer), STM




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