Canon EF-S 18-55mm f/3.5-5.6 IS STM

SLRgear Review
July 29, 2013
by Andrew Alexander

Canon has once again updated its kit lens for consumer digital SLR cameras, the 18-55mm ƒ/3.5-5.6 IS STM lens shipping with the Canon SL1, T5i and 70D cameras. Compared to previous iterations there have been some significant changes, primarily with Canon's new focusing system, STM ("Stepping" motor) which allows for fast, quiet autofocus.

The EF-S mount lens will only mount to Canon digital SLR cameras with sub-frame (APS-C) sensors. Thus, for this particular lens, it will exhibit an effective focal length of 29-88mm. The lens takes 58mm filters, and a lens hood is indicated as an optional accessory.

This lens isn't a ''constant'' lens, in that as you increase the focal length, both the minimum and maximum aperture increases. The following table reflects the increasing minimums and maximums:

The Canon 18-55mm ƒ/3.5-5.6 IS STM lens takes 58mm filters and is available now for around $200; the EW63-C lens hood is an optional extra.

Sharpness
The Canon kit lens is remarkably good, considering its economical price point; there's a little improvement between this lens and the previous (third) version of the 18-55mm, primarily at the telephoto end (55mm) where it's a little bit sharper when used wide open at ƒ/5.6. However, this comes at the expense of formerly good performance at the wide end (18mm). Our sample of this lens was very slightly de-centered to the right.

The 18-55mm ƒ/3.5-5.6 IS STM shows very good sharpness at 18mm wide-open at ƒ/3.5, a focal length/aperture combination which typically shows off the weakness of most consumer-grade lenses. If you were looking very closely, you would see that this performance isn't completely ''flat'' across the frame, but in our view it's not noticeable enough to be a problem. Stopping the lens down to ƒ/8 will provide optimal performance at 18mm - not tack-sharp, but very, very good.

The sharpness performance improves as you zoom out the focal range and stop down, achieving its optimum sharpness at 35mm and ƒ/8. Diffraction starts to set in around ƒ/11, but you don't really start to see mediocre performance until the aperture is stopped down to ƒ/16. Beyond that point, with the lens fully stopped-down, images produced are quite soft indeed.

Canon seems to have changed its mind about this lens: performance at 55mm is much better than at 18mm, and this is directly opposite to how the previous version of the lens performed. The variable aperture starts at ƒ/5.6, where we note very good sharpness (though in our copy, a little soft on the left side). Stopping down to ƒ/8 provides almost tack-sharp results at 55mm, if not for the slight de-centering.

Chromatic Aberration
Something's got to give when you're creating an economical lens, and in this case, it comes in the form of prominent chromatic aberration. Performance related to chromatic aberration in wide-angle kit lenses is typically never very good, but in the Canon 18-55mm IS STM, it's definitely prominent. CA in this lens shows up as magenta fringing in areas of high contrast, and it is possible to correct in post processing. It's most prominent in the wider angles than zoomed in, but it's always present in the corners, and it's worst when the lens is used at 18mm and ƒ/3.5.

Shading (''Vignetting'')
Corner shading isn't overly problematic in this lens - there is some, but it's only notable when the lens is used in its widest angle (18mm) and with its widest aperture (ƒ/3.5). At this setting, the extreme corners are 3/4 of a stop darker than the center of the frame. This improves to almost being negligible by ƒ/8. At other focal lengths, the only time corner shading is even slightly noticeable is when the lens is used wide open, and then the shading is almost unremarkable.

Distortion
The new lens design produces a slightly different pattern for distortion: for the 18-55mm design, distortion has typically been lots of barrel distortion when zoomed to wide (18mm), approaches no distortion in the middle, and gets a bit of pincushion distortion at the telephoto end. However, the new STM lens produces a more graceful pattern of distortion, where things are barrel-distorted at 18mm, get less so as the lens is zoomed in, and reach no distortion at the 55mm end.

Autofocus Operation
The Canon 18-55mm ƒ/3.5-5.6 IS STM has a completely new Stepping motor, which offers fast and near-silent autofocus operation. The lens takes less than a second to focus from infinity to close-focus. Attached 58mm filters do not rotate while focusing. Finally, the lens now offers full-time manual focus, meaning you can just turn the focusing ring to fine-tune your focus rather than having to switch to a manual focus mode first.

Macro
With a reproduction ratio of 1:2.9 (0.34x), the 18-55mm has decent macro capability, but it still won't replace a macro lens. Its minimum close focusing distance is 25cm (just under 9 inches).

Build Quality and Handling
At 7.2 ounces, the Canon 18-55mm ƒ/3.5-5.6 IS STM is very light, and to accomplish this it is largely (if not completely) polycarbonate plastic, though it is of a high-quality construction. The design of the lens has been changed completely: two new groups of lenses have been added (going from 11 lenses in 9 groups, to 13 lenses in 11 groups). The new lens receives a seventh diaphragm blade, presumably to improve out-of-focus elements. The cosmetic design of the lens has also changed, moving from a matte grey finish to a semi-gloss black, with slight stippling.

In terms of construction, both the lens mount and 58mm filter threads are plastic. The only information available on the lens are marked focal lengths: there are no distance scales or depth-of-field indicators. The lens only has two switches to speak of: one to enable or disable autofocus (''AF/MF'') and one to activate or deactivate image stabilization (''Stabilizer ON/OFF'').

The zoom ring is the prominent feature of the lens, at over an inch and a quarter in width. The rubber texture is a series of raised ribs that provide an easy grip. The zoom action is smooth, going from 18mm to 55mm in a seventy-degree turn, with only a minor amount of force required to transition between focal lengths. The lens extends as it is zoomed out, adding an extra 3/8'' to its overall length. Zoom creep was not a factor in our testing with this lens.

The focusing ring is mounted near the front of the lens, with a rubber ridged knurl that is easy to turn. The lens is built better for manual focus than the previous version of the lens: while the ring is only an quarter of an inch in width, and there are no stops at either the close-focusing end or infinity end to let you know you've reached the limit of focus, the focus action is actually quite smooth. Also, the ring no longer turns during autofocus operation, and full-time manual focusing is available (you don't have to switch to a manual focusing mode to fine-tune focus). As previously mentioned the front element does not turn, so attached filters will stay in place during focusing operations.

Image stabilization works as advertised, providing four stops of steadiness in our hands at 55mm, though as always the actual usefulness is going to depend largely on the capability of the individual camera user. (See our IS Test page for more details).

The optional EW-63C lens hood is petal-shaped with a bayonet mount. The hood lens reverses onto the lens for easy storage, and has a smooth black finish on the interior. Attaching the hood adds about a half-inch to the overall length of the lens.

Alternatives

Canon 18-55mm ƒ/3.5-5.6 IS USM ~$160
There's not a lot different between these versions of the lens, however it is a bit better for wide-angle, less so at the telephoto end. It's also perhaps a little better in the CA department.

Sigma 18-50mm ƒ/2.8-4.5 DC OS HSM ~$200
Sigma produces a worthy competitor at around the same price point, offering an HSM focusing system and slightly faster aperture. It's slightly sharper (except when used wide open) and has less tendency to chromatic aberration.

Tamron 17-50mm ƒ/2.8 XR Di II VC LD Aspherical IF SP AF ~$600
You'd pay a little more, but it's a bit more than a kit lens; the Tamron 17-50mm offers a wider angle, and a faster aperture. It's not as consistent for sharpness, with our review copy showing some interesting corner softness results when used at ƒ/2.8, but stopped down, it was quite decent.

Canon 18-135mm ƒ/3.5-5.6 IS STM ~$600
Another option would be to get a more dedicated all-in-one lens such as the 18-135mm. It costs signficantly more, but offers much more telephoto performance, with about the same or better optical results.

Conclusion
The lens is decently sharp when stopped down and there is a nice sweet spot around the 35mm point where you will get sharp, undistorted photographs. The four stops of image stabilization live up to the manufacturer's claims at 55mm: it shows a bit more chromatic aberration than we would like, but of course if that is a problem for a given user, there are dozens of other lenses to upgrade towards.

Product Photos

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

Still Life shot

VFA target

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.