Resolution (f5.6)

Performance at f5.6 (Zone A: centre frame)

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Canon 24mm L / f5.6 centre frame Zeiss ZF 25mm / f5.6 centre frame
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The Canon’s maximum resolution peaks centre frame at f4, whereas the slower lens predictably takes until f5.6 to reach its optimal performance. This is an exceptionally fine rendition in Zone A by the Zeiss, and is perhaps the finest we’ve ever even seen at this focal length.

Performance at f5.6 (Zone B: right side)

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Canon 24mm L / f5.6 mid frame Zeiss ZF 25mm / f5.6 mid frame
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By f5.6 the Zeiss ZF 25mm is starting to shake off the disadvantage of its smaller maximum aperture and for the first time, its Zone B performance exceeds that of the Canon 24mm L.

Performance at 24mm: f5.6 (Zone C: upper left corner)

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Canon 24mm L / f5.6 corner Zeiss ZF 25mm / f5.6 corner
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Performance at 24mm: f5.6 (Zone C: upper right corner)

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Canon 24mm L / f5.6 corner Zeiss ZF 25mm / f5.6 corner

However, the Canon retains its superiority in the corners – for resolution, at least. Note that whereas the Canon is relatively unaffected by lateral CA at wide apertures, we see purple fringing buzzing about the branches at f5.6 and up. The ZF 25mm by contrast loses its CA gremlins at f4 and here at f5.6 makes a fine showing.