In 1991, the Canon 100 mm, fully named Canon 100 mm 2.0 USM, was put on the market, and has always been somewhat snowed under by the nearly as big but cheaper Canon 85 mm 1.8. A 100 mm is at an APS-C reflex camera a very nice addition to the Canon 18-55 mm kit lens or the fast Canon 17-55 mm. A 100 mm lens has a big advantage over a 85 mm lens. Namely, if you change from the APS-C format to full frame, you immediately have the nearly perfect portrait lens in case of a 100 mm lens. Remember that lenses such as the Canon 100 mm IS Macro, Sigma 105 mm OS Macro and Tokina 100 mm Macro are tremendous rivals of the Canon 100 mm though.
Construction
The lens is made of a high quality type of plastic and the fitting is made of metal. The focus ring is smooth and without play. The filter size is, despite the high speed, only 58 mm, and the filter does not turn when focusing. The size of this lens does not change during focusing. The lens is delivered without lens hood. The autofocus is of the HSM type. Focusing is fast and nearly silent with a Canon 600D. Focusing only takes 0.21 seconds from 15 meters to 1.5 meters. Even in low light, the camera does not hunt.
Vignetting
Vignetting amounts to only 0.25 stops at full aperture, which is a very low value.
Distortion
The distortion, expressed as a percentage, is extremely low at 0.14%, and will never be visible in practice.
Flare
The lens suffers from flare at an open light source. However, and this is very positive, the image remains free from ghosting at backlight.
Resolution
The resolution, expressed in lines/ sensor height, is a bit disappointing at all apertures. Stopping down to f/4.0 improves the sharpnes a lot. ‘Real photo’s’ show that sharpnes is better than sharpnes of many consumer zoom lenses. If you compare the Canon 100 mm with the Sigma 85 mm, you will see that both lenses should be stopped down about 2 stops in order to achieve good performance.
Chromatic aberration
Chromatic aberration is a bit high at f/2.8 and should be combated software-wise.
Bokeh
The detail shots are of the left glass and the right bottle. The image comes across very ‘busy’ in the blurred parts. You can see that the blurred, round shapes are marred by circular lines. Bokeh is not that nice. |  |
 Canon EF 100 mm 2.0 USM @f/2.0 |  Canon EF 100 mm 2.0 USM @f/2.0 |
 @f/8.0 |  @f/8.0 |
Conclusion
Pro
| Con
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The Canon 100 mm in combination with an APS-C reflex camera lacks of sharpnes. On the other hand, vignetting is low and there is almost no distortion. Despite the high speed, the Canon 100 mm is built compactly. The bokeh of the Canon 100 mm IS Macro, Sigma 105 mm OS Macro and Tokina 100 mm Macro is nicer. For the lovers of ‘primes’ the Canon 100 mm can be usefull and is a nice addition to the Canon 17-55 mm.
