Lens review

Sony Carl Zeiss Sonnar T* FE 35 mm f/2.8 ZA

20 August 2016
Arkadiusz Olech

4. Image resolution

The resolution test (resolution meaning the MTF50 function) of the Zeiss Sonnar T* FE 35 mm f/2.8 ZA was based on RAW files from the Sony A7RII camera. In the case of that mirrorless device the decency level is situated near 38-40 lpmm and the best fixed focal length lenses can reach 64-67 lpmm. So far these levels are a result of testing just several primes so they might be verified a bit in further tests.

Now let’s check how the tested lens compares to those values – a graph below presents its performance in the frame centre, on the edge of the APS-C sensor and on the edge of full frame.

Sony Carl Zeiss Sonnar T* FE 35 mm f/2.8 ZA - Image resolution

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You shouldn’t expect any record-breaking values from a lens constructed with preserving small dimensions in mind, and, accordingly, there are no records here. Still it is important that already at the maximum relative aperture the Sonnar provides useful images, with the MTFs exceeding 50 lpmm. The maximum of its possibilities it reaches by f/4.0, getting to 62 lpmm. That result is several lpmm short of the best primes but, overall, you can’t have any reservations whatsoever concerning the image quality in the frame centre.

The physical dimensions of elements amounting to just more than a dozen millimeters along with a significant distance from a large, full frame sensor, made us worry about the image quality on the edge of the frame. The measurements show those fears were more than justified. The image quality on the edge of the APS-C sensor is barely on the borderline of the decency level; on full frame the lens never reaches that level at all, with results only exceeding 30 lpmm. It wouldn’t be a good result even on the 21-24 megapixel full frame sensors of Canon or Nikon cameras, used by us so far for testing full frame lenses…

To sum up the tested lens did its job well in the frame centre but on the edges of full frame it performed a bit weaker than expected.

At the end of this chapter traditionally we present crops of our resolution testing chart, taken from JPEG files which were saved along RAW files used for the analysis above.

A7R II, JPEG, f/2.8
Sony Carl Zeiss Sonnar T* FE 35 mm f/2.8 ZA - Image resolution
A7R II, JPEG, f/4.0
Sony Carl Zeiss Sonnar T* FE 35 mm f/2.8 ZA - Image resolution