Canon EF-S 18-135 mm f/3.5-5.6 IS STM review - Image resolution

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Canon EF-S 18-135 mm f/3.5-5.6 IS STM

21 September 2015

Arkadiusz Olech

4. Image resolution

The resolution test of the Canon 18–135 mm IS STM was based on RAW files from the Canon EOS 50D reflex camera. Let’s remind here that the best fixed-focus lenses attached to that body can reach as high as 52-55 lpmm and the decency level we situate near 34-35 lpmm.

First let’s check how the tested lens fares in the frame centre by glancing at the graph shown below.

Canon EF-S 18-135 mm f/3.5-5.6 IS STM - Image resolution

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The performance is good for a zoom lens with a quite wide range and two things are especially worth our praise. Firstly at every focal length at the maximum relative aperture the MTFs exceed 40 lpmm so the results are significantly above the decency level. Secondly the lens’s performance is quite even - no focal length lags behind the others.

You shouldn’t expect any resolution records from a lens of this type and, accordingly, you see here none – the values don’t exceed a level of 50 lpmm at any focal length. The predecessor was hardly better: its performance was less even and a tad worse at the maximum relative aperture. If you decide to compare the tested lens and its direct rival, the Nikkor AF-S DX 18–140 mm f/3.5–5.6G ED VR, you find out they are very much alike. The Nikkor could exceed a bit 50 lpmm but only at the shortest focal length and on the sensor of the Nikon D7000 which provides a bit higher MTFs than the sensor of the EOS 50D.

Now let’s see how the Canon EF-S 18–135 mm f/3.5–5.6 IS STM performs on the edge of the frame – an appropriate graph you can find below.

Once again you can observe quite even performance; one reservation concerns the difficult combination of wide angle and the maximum relative aperture where the MTFs are a tad below the decency level . Still on slight stopping down that problem disappears. This performance varies distinctly from that of the lens’s predecessor where the 70-135 mm focal lengths distinctly lagged behind the 18-35 mm range.

At the end of the chapter traditionally we present crops taken from photos of our resolution testing chart saved as JPEG files.

Canon 50D, JPEG, 18 mm, f/3.5