Lens review

Sony FE 135 mm f/1.8 GM

12 September 2022
Maciej Latałło

4. Image resolution

Our resolution tests (resolution meaning MTF50 function values) of Sony FE lenses are based on RAW files from the 42.4 Mpix sensor of the Sony A7R II or Sony A7R III camera. In the case of this kind of detector the decency level we set about 39-41 lpmm and the best fixed focal length lenses have been able to reach 75-80 lpmm, with record-breaking devices exceeding slightly 80 lpmm. So far, the following lenses have fared the best: the Voigtlander Apo Lanthar 50 mm f/2 E (81.0 lpmm), and the Sigma C 65 mm f/2 GD DN (82.7 lpmm) and the Sony FE 20 mm f/1.8G (83.7 lpmm).

Let's check how the Sony FE 135 mm f/1.8 GM fares – its results in the frame centre and on edges of the APS-C sensor and full frame presents a graph below.

Sony FE 135 mm f/1.8 GM - Image resolution

The performance in the frame centre is undoubtedly excellent. Already at the maximum relative aperture you deal with a good level of over 60 lpmm and it improves very quickly on stopping down. As a result, by f/4.0, you deal with a sensational value, exceeding 80 lpmm. The tested lens actually brushes against resolution records!

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Unfortunately, when it comes to edges of the frame we don't have such good news. Usually the resolution on the edge of the frame of fast lenses designed for DSLR cameras with focal lengths of 105-135 mm is just slightly weaker than their resolution in the frame centre. In the case of the Sony FE 135 mm f/1.8 GM you see a distinct decrease; as a result the edge of the frame lags noticeably behind the values we see in the centre.

Still, we have to emphasize the fact that these results aren't bad at all. Even on the edge of the full frame, near f/1.8-2.0, you deal with MTFs that are on the borderline of the decency level so there are no serious reasons to complain. We feel unsatisfied only because we have been spoilt by the performance of good lenses designed for reflex cameras, that's all.

Traditionally, at the end of this chapter we present crops taken out of images of our resolution testing chart, saved as JPEG files along RAW files which were used for the analysis above.

A7R III, JPEG, 135 mm, f/1.8
Sony FE 135 mm f/1.8 GM - Image resolution
A7R III, JPEG, 135 mm, f/4.0
Sony FE 135 mm f/1.8 GM - Image resolution