|Canon EF-S 18-135mm f/3.5-5.6 IS STM on EOS 70D|
Kit lenses are typically middling, as per their very nature. The lens needs to be inexpensive enough to make the price of the camera kit affordable, but the optical quality can't be so cheap that it would turn off a buyer from ever delving deeper into a manufacturer's lens lineup. Because of this formula, kit lenses usually end up in the "not bad for it's price" category. "Hey, it's only opens as wide as f/5.6, but it's still sharp at that aperture!"
The Canon EF-S 18-135mm f/3.5-5.6 IS STM is one step up from such lowly aspirations, and is offered as the second kit option on the T5i (EOS 700D) after the 18-55mm STM, and as the primary kit lens option for the 70D. Like the Nikon AF-S DX NIKKOR 18-140mm f/3.5-5.6G ED VR, the Canon lens feels more at home on the advanced-enthusiast body than it does on the consumer body. The EF-S 18-135mm covers the full frame equivalent of 29-216mm, which technically takes it out of the normal-zoom bracket and puts it into the lower end of the super-zoom category. Traditionally, such lenses have been Jack-of-all-trades but master of none. Does the Canon EF-S 18-135mm STM break that mold?
Build and Operation
Though not heavy nor bulky, this lens is a bit on the fat and long side for a consumer camera. When attached to the 70D, the total camera/lens package is substantial enough that non-photographic acquaintances are going to ask you where you are going with your "paparazzi camera." This lens mounted on a 70D will fit in a medium sized messenger bag with room to spare.
|EW-73B Hood for Canon 18-135mm STM|
The filter size is 67mm and the front element does not rotate. The focus ring is electronic; there is no mechanical connection between it and the optical hardware inside. Manually focusing this lens is reminiscent of using a Micro Four Thirds camera. The accessory petal hood is the EW-73B. As is unfortunately typical for non-L Canon lenses, the hood is an (expensive) extra. However, the hood is of a higher quality construction than entry-level parts as it does have velvet lining on the inside surface to better absorb stray light.
As per Canon's other STM lenses, the focus speed is silent and utterly smooth. When it comes to focus acquisition speed, it doesn't have the quick snap of the USM driven lenses, but the utter silence of the lens' operation makes it a pleasure to use.
As with the other STM lenses, the 18-135mm plays well with live view and tends to do better with video focusing than comparable USM lenses.
In Daily Use
Because of the wide focal length range, this is a lens that can be used in a great many difference circumstances. However, what you gain in zoom versatility, you lose in depth of field control. That doesn't mean that you cannot achieve a blurred-out background due shallow depth of field, it just requires bring the lens closer to the subject, as below with the orchid.
|Canon EOS 70D: 1/125s, f/5.6, 85mm|
Pretty much any DSLR lens can achieve this effect (often mistakenly referred to as "bokeh," which is a description of the quality of the blur, not the amount.) However, with a variable-aperture zoom like the 18-135mm, bokeh is not particularly achievable at distances typically used to photograph people.
As is de rigueur nowadays, the 18-135mm is stabilized. Don't expect miracles; usually camera companies quote a figure of roughly four stops of hand-held advantage. A more practical (and conservative) rule of thumb is to factor in a more modest two-stop advantage; three if you are fairly certain of your technique. In other words, a two-stop advantage means that for non-moving subjects, you can use a shutter speed that is four times as long as what you would normally be using without image stabilization. Keep in mind that there are diminishing returns; 1/10s is roughly the practical limit of any sort of hand-held shooting.
|Canon 70D: 1/80s, f/4.5, ISO 640|
As a walk-about lens, the 18-135mm is adept at framing many situations, but without the wider aperture of a fast-zoom lens or prime, a sense of depth takes some work to achieve. In the picture of the states below, there isn't much that can be done to de-focus and de-emphasize the background. The diagonal lines created by the benches and the shadows compositionally add back the suggestion of depth.
|"Steveston's Legacy" - Norm Williams|
Though there are wider lenses, 18mm on an EF-S camera is wide enough for most scenery shots. Once you go past this in to the ultra-wide range (10-20mm), composition starts becoming a challenge. With wide angle, there's always the temptation to try to "fit it all in," but many such shots don't come alive unless there is something for the eye to anchor on. There's some barrel distortion, as would be expected at the wide end of a lens with such a wide zoom range. However, these are out of camera JPEG's, meaning that the camera is doing some electronic correction. The RAW data would show significantly more distortion at the wide end; by 50mm it's more or less gone, and becomes a slight pin-cushion towards the long end of the lens.
|Canon 70D: 1/160s, f/8, ISO 100|
Uncorrected lateral chromatic aberration is on the high side for this lens, but vignetting is reasonably well controlled. For a kit lens, sharpness is fairly consistent throughout the focal length range. There are no obvious weaknesses, but neither does this lens achieve the biting sharpness of Canon's best L lenses.
Just to emphasize what "all-arounder" actually means, the following two shots were shot in the middle of the night, without a tripod. (Always watch your step when you are walking out on the docks in the dark!) Mind you, ISO 3200 and 6400 were necessary and there's a lot of noise-reduction and editing that was added back in during post-processing, but these are remarkably usable pictures for a "slow" variable-aperture lens. ("Usable" is in the eye of the beholder, but since there isn't much in the way of fine detail in either picture, pouring on the noise reduction is acceptable in either case.)
|Canon 70D: 1/20s, f/4, ISO 3200|
|Canon 70D: 1/5s, f/4, ISO 6400|
Usually, enthusiasts buying replacement DSLR skip the kit option and buy body-only. Even if you already have a f/2.8 standard-zoom, it's worth checking out the kit options that include this lens. As a do-everything lens, the 18-135mm is a better choice than the older Canon EF-S 18-200mm f/3.5-5.6 IS as it is sharper and does not give up much in terms of actual lens reach despite the 65mm difference in maximum focal length. Like most kit lenses,it's really not worth buying this lens by itself; the MSRP is roughly $550 USD. However, even if you prefer to buy body-only, it would still be worthwhile to get the kit option instead, and then sell this lens as it has appeal to a broad number of users on the secondary market.
Overall, still a kit lens, but a very competent one at that.