Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens Review

Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens
Note: The Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens has been replaced by the Canon EF-S 18-135mm f/3.5-5.6 IS USM Lens.
In-Depth Review

The Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens is a significant upgrade from the standard-at-review-time 18-55mm IS kit lens. It is an upgrade in many ways, but the 18-135's most attractive features are a wide (7.5x) focal length range, a relatively light weight & small package, a good IS (Image Stabilization) implementation and a low price (a great value in a DSLR kit – medium price otherwise).

The 18-135 STM arrived in a Canon EOS Rebel T4i DSLR kit just before my scheduled trip to northern Maine. The pair became inseparable travel companions on this trip. Their light weight, small size, wide image stabilized focal length range and good image quality made this combo a great choice for long periods of carrying.

18-135 STM Sample Picture

The Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens sample image above was captured at Island Pond in the North Maine Woods using a Canon EOS Rebel T4i. Settings were 24mm, f/8, 1/80 and ISO 100. I was attending a large family social event when the above scene presented itself. I had this small, light camera and lens combination with me for one these just-in-case situations.

18-135 STM Top View with Hood

Multiplying the 18-135's focal length range by 1.6x shows that the 18-135 mounted on an APS-C body will deliver an angle of view equivalent to a 28.8-216mm lens mounted on a full frame format DSLR. This is an excellent general purpose focal length range, starting at a moderately wide angle and going to a nicely-long focal length. Here is an example of what this focal length range looks like:

18-135 STM Focal Length Range Example

18mm | 24mm | 35mm | 50mm | 85mm | 135mm

Image stabilization is an 18-135 STM feature that I wish was present in every lens I own - one that helps insure the sharpest image possible while shooting handheld.

Canon rates this IS implementation at 4 stops. Standing, handheld testing with this lens and IS switched off indicated that I need shutter speeds of 1/25 at 18mm and 1/160 at 135mm for a good keeper rate. With IS on, my acceptable keeper rate shutter speed was about .4 and 1/6 seconds at 18mm and 135mm respectively. That is an impressive nearly 4 stops of improvement at 18mm and better than 4 stops at 135mm.

Here is what that difference looks like:

18-135 STM Image Stabilization Example

The above 18mm .4 sec exposure examples were captured in RAW format using a Canon EOS Rebel T4i/650D. Image stabilization works – and is useful even at 18mm. Of course, just because you can shoot at these long shutter speeds doesn't mean you should. IS does not keep your subject still. People move. The wind blows.

The quietness and smoothness of the 18-135 STM's image stabilization implementation make it especially well-suited for video capture. This IS system is silent – I don't hear any IS sound even with my ear next to the lens – the T4i's in-camera stereo mics do not pick up IS sounds. It is also well behaved – IS does not cause the viewfinder to jump – also helpful for video capture. As always with in-lens IS, the photographer is presented with a stabilized viewfinder (or LCD). This makes subject framing easier – and makes your photography a more pleasant experience.

The 18-135 STM features "... dynamic IS, effective when shooting while walking since it expands the IS range." This mode is automatically activated when shooting in movie mode.

The 18-135 STM also features auto-panning detection – a switch setting is not required for the lens to stabilize in one direction only. Auto tripod sensing is also featured. Canon recommends turning IS off when using a tripod (to conserve a small amount battery life) and leaving IS on when using a monopod (to assist in stabilizing the image).

Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens Mounted on Canon EOS Rebel T4i

IS is especially helpful on a relatively narrow aperture lens such as this one. Details of the max aperture step-down as focal length is increased are in the Lens Specifications link at the top of this review, but this is not a good lens for stopping action in low light levels – at least not without a flash. The max aperture step-down improved slightly from the previous 18-135 in our tests.

Canon EF-S 15-85mm f/3.5-5.6 IS Lens  15mm18mm27mm38mm61mm
Canon EF-S 17-55mm f/2.8 IS Lens17mm      
Canon EF-S 17-85mm f/3.5-5.6 IS Lens   17mm26mm38mm47mm
Canon EF-S 18-55mm f/3.5-5.6 IS II Lens  18mm24mm29mm39mm47mm
Canon EF-S 18-55mm f/3.5-5.6 IS Lens  18mm24mm28mm39mm47mm
Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens  18mm24mm35mm50mm76mm
Canon EF-S 18-135mm f/3.5-5.6 IS Lens  18mm22mm31mm41mm64mm
Canon EF-S 18-200mm f/3.5-5.6 IS Lens  18mm24mm40mm50mm90mm
Canon EF 28-135mm f/3.5-5.6 IS USM Lens  28mm37mm50mm67mm85mm

My previously-scheduled trip to Maine did not allow lab evaluation of the 18-135 STM prior to leaving, but I wanted to try this lens out while traveling – and did so. For most of the trip, I kept the 18-135 STM's aperture stopped down to a safe-for-most-lenses f/8 while shooting mostly landscape/scenics. My laptop's monitor is too sharp, but even taking this fact into consideration, the 18-135 STM results while traveling appeared reasonable – as expected.

Immediately upon return from my travels, the Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens went through the standardized testing. The lab-grade, repeatable results from the ISO 12233 resolution chart testing usually tell the full story of a lens's image quality. In the case of the 18-135 STM, these results show impressive performance. Performance rivaling a favorite lens of mine – the Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens.

In the lab, the 135 STM is nicely sharp from the center into the corners throughout the entire focal length range – with some modest softness at 85mm. Stopping down has relatively little effect on the results aside from reduced vignetting.

Reviewing my trip images on a quality external monitor left me not-quite-as-excited. I was not disappointed, but my excitement was tempered somewhat by some softer corners being noticeable. Outdoor comparison testing between the new and old 18-135mm lenses indeed showed some complexity to their image quality with these lenses showing more-similar results overall. Often one lens was sharp on one side of the frame while the other lens was sharp on the other side – asymmetry is an indicator of less-than ideal construction quality. I could easily create a comparison that made either lens appear to shine against the other. Let me show you an example.

Following are four comparison crops taken from two Rebel T4i images – one from each 18-135mm lens set to 35mm with a wide open f/4.5 aperture. The Standard Picture Style was used with sharpness set to 0 (low – and equal to 1 on previous APS-C DSLR bodies). The tree branch crops are taken from a top left area of the frame and the rock crops are taken from an area near the bottom right. Subjects showing in these images are along the expected plane of sharp focus.

18-135 STM Image Quality

Canon EF-S 18-135mm IS STM Lens: Top Left | Bottom Right
Canon EF-S 18-135mm IS Lens: Top Left | Bottom Right

If I want to make the STM look better, I don't show the bottom right. And vice versa. My 18-135mm IS STM Lens delivers a better image on average, but it is not better enough to land it in a higher class than my pervious version 18-135mm IS Lens.

Full frame-compatible lenses used on APS-C sensor format bodies typically show little or no vignetting – or distortion. With their smaller image circles, APS-C-only EF-S lenses generally show both.

The 18-135 STM shows more than 2 stops of vignetting in the outer image circle (frame corners) at 18mm f/3.5. Vignetting decreases to about 1.4 stops as the focal length is increased to 35mm and then remains relatively steady through 135mm. Though these numbers are slightly higher than from the previous 135 IS lens, they are not bad. Stopping down, as usual, reduces vignetting a noticeable amount.

As is typical for a zoom lens in this focal length range, the 18-135 IS STM Lens exhibits relatively strong barrel distortion at 18mm. Increasing focal length dials in barrel distortion reduction which takes the form of pincushion distortion beyond the approximately 24mm crossover focal length. Pincushion distortion becomes moderately strong by 85mm. Distortion results are similar for the 18-135 IS and 18-135 IS STM lenses.

The 18-135 STM shows nearly no flare over the entire focal length range (except at around 35mm) with a wide open aperture. Only slightly more flare is apparent at f/8 and slightly more at f/11 and f/16.

Chromatic aberration is rather strong in outer portions of the image circle at the ends of the 18-135mm IS STM lens's focal length range. CA amounts diminish to practically none in the longer midrange focal lengths.

With relatively narrow apertures at their max, this is not the best lens to select for blurring the background. Still, blurs can be created with a relatively close subject. The 18-135 IS STM received an extra aperture blade – now featuring a 7-rounded-blade aperture (up from 6). Still, the out-of-focus blur quality from this lens is not especially nice - especially when harsh concentric rings are created from specular highlights at stopped down apertures. Here are 135mm examples:

18-135 STM Bokeh Comparison

18-135 STM Extended with Hood on Rebel T4i

The STM in the Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens product name refers to the new-for-Canon stepping motor driving autofocus. Designed with video recording in mind, the 18-135 IS STM focuses smoothly while in continuous Movie AF mode. The stepping motor does not seem quite as fast as the Ring USM implementation in the EF-S 15-85mm IS Lens, but it seems faster than the Micro Motor. It is however, much quieter than the 18-135 IS lens's noisy micro motor – and even quieter than the 15-85mm IS lens's Ring USM-driven motor. The Rebel T4i's built-in stereo mics do not capture any AF sounds from this lens.

Focus adjustments do not cause the subject framing to shift – alignment remains tight. Also important for video capture is that focus breathing is not a problem with this lens – subjects do not change size as they go in and out of focus. And also helpful for video capture is that this lens tests to be essentially parfocal, meaning that focus distance settings do not change as focal lengths are changed. Of course, the depth of field at this lens's relatively narrower max apertures makes this feature less challenging to achieve – but it is still helpful for shooting video.

The 18-135 IS STM Lens has been focusing accurately for me One shot AF mode. As this is not a made-for-action photography lens, I have not stress tested this lens in AI Servo mode.

STM uses a focus-by-wire design that requires the camera meter to be live (more accurately, for the lens to be wakened from its sleep mode) for electronically controlling the focus distance setting even in switched-to-MF mode. FTM (Full Time Manual) focusing is available, but only after AF completes in One Shot mode with the shutter release remaining half-pressed.

18-135 STM Angle View

This lens focuses internally and attached filters do not rotate during focusing.

The nicely-sized focus ring is smooth with a long about-360º rotation. The focus ring functionality is very-much-improved over the prior model. The shifted-back location of the focus ring is another improvement.

No focus distance setting information is available on this lens – there is no focus distance window.

Upgraded is the 18-135 STM's minimum focusing distance and its corresponding maximum magnification spec. These new figures are near best-in-class:

ModelMin Focus Distance "(mm)Max Magnification
Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens13.8(350)0.21x
Canon EF 16-35mm f/2.8L II USM Lens11.0(280)0.22x
Canon EF 17-40mm f/4.0L USM Lens11.0(280)0.25x
Canon EF-S 17-55mm f/2.8 IS USM Lens13.8(350)0.16x
Canon EF-S 17-85mm f/4-5.6 IS USM Lens11.8(300)0.20x
Canon EF-S 18-55mm f/3.5-5.6 IS II Lens9.8(250)0.34x
Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens15.4(390)0.28x
Canon EF-S 18-135mm f/3.5-5.6 IS Lens19.3(490)0.21x
Canon EF-S 18-200mm f/3.5-5.6 IS Lens17.7(450)0.24x

Maximum magnification specs, as usual, increase with extension tubes. The 18-135 STM's magnification range numbers for the Canon EF 12mm Extension Tube II are 0.43-0.09x and 0.61-0.21x for the Canon EF 25mm Extension Tube II. This lens is not compatible with Canon Extenders.

Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens Product Images

MFD |    MFD |    w/ Hood:  MFD |    MFD |    Rotated        Compare >

The 18-135 STM features a simple, smoothly-shaped exterior that is practically all zoom and focus rings. The zoom ring located toward the rear of the lens is my preference for positioning. Again featured is a quality plastic barrel with an attractive finish and the usual ribbed-rubber-covered rings.

Noticeably improved from the 18-135 IS is that there is practically no play in the 18-135 STM's extended lens barrel – and essentially no play in the focus and zoom rings. The rings are smooth with a nice amount of dampening. A zoom lock switch is now provided (locks the zoom ring at 18mm), but my lens will not need it for a long time - the pull of gravity is not nearly strong enough to extend this lens.

The 18-135 STM's external design varies only slightly from the 18-135 IS. The more-rear-set focus ring is a nice improvement – this is a more-easily usable location for this ring. The STM is slightly shorter when retracted, but slightly longer when fully extended at 135mm and the STM is slightly heavier. The differences are not enough to matter – both lenses are relatively small (especially narrow) and light. The length of the STM's zoom extension is 1.96" (49.6mm).

ModelWeight oz(g)Dimensions w/o Hood "(mm)FilterYear 
Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens20.3(575)3.2 x 3.4(81.6 x 87.5)72mm2009
Canon EF 16-35mm f/2.8L II USM Lens22.6(640)3.5 x 4.4(88.5 x 111.6)82mm2007
Canon EF 17-40mm f/4.0L USM Lens16.8(475)3.3 x 3.8(84 x 97)77mm2003
Canon EF-S 17-55mm f/2.8 IS USM Lens22.8(645)3.3 x 4.4(83.5 x 110.6)77mm2006
Canon EF-S 17-85mm f/4-5.6 IS USM Lens16.8(475)3.1 x 3.6(79 x 92)67mm2004
Canon EF-S 18-55mm f/3.5-5.6 IS II Lens7.1(200)2.7 x 3.3(68.5 x 84.5)58mm2011
Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens16.9(480)3.0 x 3.8(76.6 x 96)67mm2012
Canon EF-S 18-135mm f/3.5-5.6 IS Lens16.1(455)3.0 x 4.0(75.4 x 101)67mm2009
Canon EF-S 18-200mm f/3.5-5.6 IS Lens21(595)3.1 x 4.0(78.6 x 102)72mm2008

For many more comparisons, review the complete 18-135 STM Specifications using the site's Lens Spec tool.

The size and weight of the 18-135 STM are such that you can take this lens everywhere without much effort. Here is a look at many review-time-current Canon EF-S lenses:

18-135 STM Compared to Similar Lenses

Positioned above from left to right in their fully retracted positions are the following lenses:

Canon EF-S 18-55mm f/3.5-5.6 IS II Lens
Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens
Canon EF-S 17-85mm f/4-5.6 IS USM Lens
Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens
Canon EF-S 18-135mm f/3.5-5.6 IS Lens
Canon EF-S 18-200mm f/3.5-5.6 IS Lens
Canon EF-S 17-55mm f/2.8 IS USM Lens

The same lenses are shown below in their fully extended states with their lens hoods in place.

18-135 STM Compared to Similar Lenses with Hoods

The optional petal-shaped Canon EW-73B Lens Hood is relatively compact, but not so much that it does not provide protection for the front lens element. With the hood installed, the Rebel T4i's built-in flash is partially blocked (lens hood shadow in frame) up to about 32mm (this lens does not block the built-in flash with no hood installed.

The Canon LP1116 Lens Pouch is also optional for this lens. I suggest buying a different case – such as a Lowepro Lens Case.

The 18-135 STM accepts 67mm threaded filters. This is a common size for Canon glass. Even the side-pinch-only Canon version I lens caps are not difficult to install or remove with this hood in place.

Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens compared to Canon EF-S 18-55mm f/3.5-5.6 IS II Lens – Top View

As seen in various examples in this review, the current standard entry-level Canon EF-S 18-55mm f/3.5-5.6 IS II kit lens is smaller than the 18-135 STM. It is also less expensive. In reality, the 18-55 IS II is a good value – but the 18-135 STM is a much better lens in many ways – including its AF and MF capabilities and the longer focal length range. I feel that the upgrade to the 18-135 STM is worth the extra cost – especially when it is available in a kit.

Canon EF-S 18-135mm f/3.5-5.6 IS STM Lens compared to Canon EF-S 18-55mm f/3.5-5.6 IS II Lens – Angle View

The 18-135 IS STM hit the streets costing only slightly more than the prior 18-135 IS. The 18-135 IS STM is worth the small price difference for many reasons already discussed.

I still prefer the Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens for general purpose uses not needing a wide aperture (typically stopping action in low light and creating a strong background blur). As of 18-135 STM review time, the price of the 18-135 STM is approaching the price of the 15-85 (though, again, the 18-135 STM is a better value in the with-DSLR kit).

The evaluated 18-135 STM was purchased retail online. And it has now traveled the northeast US coast including Kennebunkport, Maine (below) as a travel lens – a purpose for which it is well-suited.

18-135 STM Sample Picture 2

The 18-135 STM sample image above was captured in using a Canon EOS Rebel T4i. Settings were 135mm, f/8, 1/160 and ISO 100.

18-135 STM Top View Extended with Hood

If your budget stops at the Canon EF-S 18-135mm f/3.5-5.6 IS STM lens's price tag, it well may be the right lens choice for you. It is a small, light and reasonably-priced lens with effective image stabilization and a great general purpose focal length range. This lens's video-specific capabilities are another compelling reason to choose it.

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