Canon EF 35 mm f/1.4L USM review - Image resolution

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Canon EF 35 mm f/1.4L USM

29 May 2009

Arkadiusz Olech

4. Image resolution

The lens was tested in a standard way, using the RAW files from the Canon 20D. Additionally we decided to check how it fares on the full frame detector of the Canon 5D.

Let’s start with the lens’s performance on a smaller sensor, The graph below shows the frame center and corner performance.

Canon EF 35 mm f/1.4L USM - Image resolution

When it comes to the frame center, we broke two record so there’s hardly anything to complain about. Firstly, none of the lenses tested by us before has obtained a better f/1.4 result and part of them had it easier, working on the 10 megapixels sensors. A result of over 30 lpmm is a proof that even working at maximum relative aperture the lens will take sharp and useful photos. The second record is the result obtained by f/5.6, on the level of 44.1 +/- 0.5 lpmm, which supersedes the Tamron 2.8/90 lens in this category (we forget for a while about the Sigma 2.8/10 result because it was too close to the chart so was given an advantage). These results made us note that the holes in lens elements, unless they occupy a significant areas, do not influence the picture quality – interesting!

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The frame picture quality is perhaps not outstanding and record-breaking but also you can hardly find a fault with it. Only by f/1.4 the lens doesn’t reach 30 lpmm but for higher aperture values it exceeds that level without a problem, sometimes even significantly, which allows you to take sharp or very sharp pictures.

At the end of the 20D performance description we present the test chart excerpts, saved as JPEG files, at f/1.4 and f/4.0

Now let’s progress to the full frame performance, which can be seen in the picture below.

First question, which arises here is: why these values are so low? The answer is not so difficult to find. The linear pixel density on a full frame Canon 5D detector is almost 30 % lower than on a smaller 20D detector. In fact the MTF values are lower by the same factor because the 20D record result by f/5.6 is exactly 29% higher than 34 lpmm, reached on 5D by f/5.6. Small wonder that our assessment of the frame center performance will be exactly the same as for 20D – it is truly outstanding, as it befits an expensive L-series!

With the frame corner results, there is some modification. The full frame edge is not the same as on the APS-C sensor and it can be noticed clearly by f/1.4 and f/2.0, which stand out quite a lot from the center results. If we use the lens wide open and we want to have sharp edges we have to stop down to at least f/2.8.

In the picture below we present how big differences we found between these two detectors performances; you can see the excerpts of the left-hand upper corner of the test chart, obtained on 20D and 5D by f/1.4.