The 24mm World Cup
Group C: Regular f2.8 Prime Lenses

Canon 24mm f2.8 v Olympus 24mm f2.8 v Sigma 24mm f2.8 v Yashica ML 24mm f2.8:
Corner Performance at f5.6 (100% Crops)

3 points	4 points
Canon 24mm at f5.6 (corner)	Olympus 24mm at f5.6 (corner)
Sigma 24mm at f5.6 (corner)	Yashica ML 24mm f5.6 (corner)
2 points	2 points

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Once again, the Canon turns in an evenly controlled corner performance, just squeezed out of the top spot by the Olympus, with the Sigma and Yashica trailing in joint last place.  By now you'll probably have noticed that the Yashica is showing the age of its coatings: compared to the modern lenses, it has a distinctive low-contrast 'glow', yet resolves reasonably strongly across the frames. Makes you want to track down a longer version for portraits.

Centre Performance at f5.6 (100% Crops)

1 points	4 points
Canon 24mm at f5.6 (centre)	Olympus 24mm at f5.6 (centre)
Sigma 24mm at f5.6 (centre)	Yashica ML 24mm at f5.6 (centre)
3 points	2 points

Here again, the gulf is a little wider than the points suggest: the Olympus and Sigma are very close, but both are better than the Yashica or the Canon by some margin. This particular sample of the Canon 24mm shows some evidence of de-centering: the left side of the image seems slightly better resolved than the right. Just the sort of problem you'd expect to encounter with an adapted lens . . . .