Canon EF 40mm f/2.8 STM review

Thursday January 17 2013

Lens Review
Introduction | Canon EF 40mm f/2.8 STM lens performance | Canon EF 40mm f/2.8 STM versus competition | Conclusion

Sharp and bright, but strong vignetting at widest apertures

Considering its relatively low price, the EF 40mm f/2.8 STM was a solid performer on our DxOMark Camera Lens Ratings. When mounted on a Canon EOS 5D Mark II, it rates among the top seven standard prime lenses (with a focal range between 35mm and 85mm) achieving an overall DxOMark Score of 26.

Strengths of the Canon EF 40mm f/2.8 STM include resolution, as evidenced by its Sharpness score of 15P-Mpix. Additionally, our sharpness measurements and field maps (below) indicated that the lens delivered relatively consistent edge-to-edge sharpness from f/2.8 to f/11.

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Canon EF 40mm f/2.8 STM: Acutance in the field

Other strengths include its low geometric distortion and well-controlled chromatic aberration as indicated by its low Chromatic Aberration score of 10µm.

The one weakness of the Canon EF 40mm f/2.8 STM was the strong vignetting evident at the widest apertures. You can see from the vignetting field maps below that at f/2.8, there is heavy shading across 2/3 of the field.

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Canon EF 40mm f/2.8 STM: Shading in the field