Canon EF-M 55-200mm f/4.5-6.3 STM IS Review / Test - Analysis
Lens Reviews - Canon EOS (APS-C)

Distortion

Unlike other mirrorless manufacturers, Canon does not believe in (lossy) digital auto-correction of distortions which is certainly commendable. And they are certainly showing that it is also not necessary by avoiding extreme distortions with little efforts. The Canon EF-M 55-200mm f/4.5-6.3 STM IS produces a slight barrel distortion at 55mm. There are moderate pincushion distortions at 135mm and 200mm but they remain within acceptable limits.

Vignetting

The vignetting charateristic is typical for a native APS-C tele zoom lens. Thus the Canon lens produces high and noticeable vignetting at max. aperture but the issue is pretty much gone when stopping down by 1 f-stop.

MTF (resolution)

Canon has an excellent reputation when it comes to tele lenses but we don't see any greatness with the Canon EF-M 55-200mm f/4.5-6.3 STM IS. The sweet spot of the lens is clearly at the lower end of the zoom range. At 55m the quality is very high across the image field. However, the quality falls apart the more you zoom out. At 135mm, the center quality is still good to very good but the image borders are mediocre at fully open aperture. Stopping down to f/8 is a good idea because it boosts the quality quite a bit without reaching truly impressive levels though. 200mm f/6.3 is the weakest spot - unsurprisingly. The image center manages to stay good at f/6.3 but the corners deteriorate even further. Better stop down again for better results here.

The centering quality of the tested sample was acceptable.

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 low between 55mm and the middle range. At 200mm they are getting noticable with an average width of 1.8px at f/6.3. Stopping down helps a bit though. 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.