Canon EF-M 15-45mm f/3.5-6.3 STM IS - Review / Test - Analysis
Lens Reviews - Canon EOS (APS-C)
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Many mirrorless lenses rely on digital auto-correction here but fortunately Canon follows a more conservative approach. The Canon EF-M 15-45mm f/3.5-6.3 STM IS produces a strong degree of barrel distortion at 15mm but at ~3.3% this is still moderate compared to what we've seen elsewhere in the mirrorless lens segment (Hello Fuji & MFT?). The distortions are equalized at 28mm followed by a moderate barrel distortion (1%) at 45mm. The latter is a little bit unusual actually - pincushion distortion is much more common at the long end of the zoom range.


Unfortunately vignetting is a massive weakness - again. We have seen this problem in our previous EF-M reviews so by now we are pretty confident to state that this isn't solely a lens issue. It seems as if Canon just took their APS-C sensor developed for some of their DSLRs and this just wasn't the smartest thing to do due to much closer distance to the lens' rear element. It seems as if the sensor doesn't like the more extreme light angles towards the corners.

The "raw" light falloff is shockingly high. At 15mm @ f.3.5, the Canon lens holds the new negative record (again) with a whopping 3.6EV(!!!). This is more than double our usual scale for APS-C format lenses! Even at f/11, you can observe a falloff of ~1.4EV (f-stops). The situation isn't quite as bad at 28mm where f/5.6 is sufficient to solve most of the issue. At 45mm it isn't overly relevant anymore.

Consequently you should leave the vignetting auto-correction activated although you'll have to live with increased corner noise at the wide-end in this case.

MTF (resolution)

The resolution figures of the Canon EF-M 15-45mm f/4-5.6 STM IS are quite decent. The weakest spot is at 15mm @ f/3.5. While the center quality is great, the outer image field is soft. However, stopping down to f/5.6-8 boosts the sharpness to a very good quality across the image field. The center quality decreases gradually towards the long end of the zoom range but the corners are quite good even at max. aperture. Diffraction has a limiting effect from f/11 onward.

The centering quality of the tested sample was Okay (albeit not great)

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations

Chromatic Aberrations (CAs)

The amount of lateral CAs is very moderate with an average CA pixel width at the image borders around the 1px mark. CAs are usually taken care of by the camera's auto-correction or in various RAW converters (Canon DPP, Adobe Photoshop, etc) so there's little to worry about here anyway. CA auto-correction is a lossless procedure.


The Canon EF-M 15-45mm f/3.5-6.3 STM IS may not be their most glorious offering but it is actually a quite decent lens. Unless we are talking about the wide-open performance at 15mm, it is a quite sharp lens. Image distortions as well as lateral CAs are about average for a lens in this class. There's one substantial weakness - the dramatic vignetting at 15mm although most of the issue does probably originate in the image sensor rather than the lens. In any case it's a good idea to leave image auto-correction activated here.

The build quality of this retractable, tiny lens is nothing to rave about but still livable. If you don't like plastics this one is not for you though. The auto-focus relies on Canon's noiseless STM (Stepping Motor) which also operates reasonably fast albeit not class-leading. Please note that the AF speed is also related to the performance of the camera so it may and it will improve with the next camera generations. The image stabilizer is certainly a very valuable feature given the fact that the lens is very slow especially at its 45mm setting.

The Canon EF-M 15-45mm f/3.5-6.3 STM IS competes against its in-house mate, the Canon EF-M 18-55mm f/3.5-5.6 STM IS. We haven't tested the latter formally yet but it is, most likely, the better lens both optically and especially mechanically so the remaining niche for the EF-M 15-45mm f/3.5-6.3 STM IS is a bit narrow.

Optical Quality: to    
Mechanical Quality:
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