Lens review

Sigma C 65 mm f/2 DG DN

27 February 2021
Maciej Lata³³o

4. Image resolution

The resolution test (resolution meaning the MTF50 function values) of Sony FE lenses we base on RAW files from 42.4 Mpix sensors of the Sony A7R II and Sony A7R III cameras. 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 exceed 70 lpmm. So far, two Voigtlander lenses have fared the best: the Apo-Lanthar 65 mm f/2 Aspherical 1:2 Macro (78.5 lpmm) and the Nokton 50 mm f/1.2 (78.6 lpmm). The Sigma A 105 mm f/2.8 DG DN Macro (80.4 lpmm) remains very close behind them.

Let's check how the Sigma C 65 mm f/2 DG DN Macro compares – its results in the frame centre, on the edge of the APS-C sensor and on the edge of full frame presents a graph below.

Sigma C 65 mm f/2 DG DN - Image resolution

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When you starts thinking that you won't have to change the introduction section of this chapter for a longer period of time you get an inconspicuous Sigma for testing and you are in for a very positive surprise. Already from the maximum relative aperture the results are simply sensational - you deal here with a resolution close to almost 70 lpmm. By f/2.8 and f/4.0 this lens breaks resolution records and both these aperures get identical values within the margin of error. Officially, the result by f/4.0 was a tad higher, amounting to 82.7 ±1.3 lpmm and it is also our new Sony 42.4 Mpix sensor resolution record.

The performance on the edge of the APS-C sensor should also be described in only favourable terms. Already up from the maximum relative aperture you see a very high level of 56 lpmm and on stopping down the lens is able to exceed 70 lpmm. It's worth mentioning these results are better than those of the Sony Carl Zeiss Sonnar T* FE 55 mm f/1.8 ZA in the frame centre. In this category the Sigma simly outclasses its rival that some people call (as you see, quite unreasonably) a 'mini Otus'.

We also don't have the slightest reservations concerning image quality on the edge of the full frame sensor. By f/2.0 the resolution is about 50 lpmm so very safely above the decency level. The lens stopped down to near f/4.0 is able to exceed 60 lpmm so can generate images of good quality.

It's clear that resolution is a very strong point of the Sigma. Now we are really curious how it will fare in other testing categories.

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

A7R III, JPEG, 65 mm, f/2.0
Sigma C 65 mm f/2 DG DN - Image resolution
A7R III, JPEG, 65 mm, f/4.0
Sigma C 65 mm f/2 DG DN - Image resolution