Lens review

Sony FE 40 mm f/2.5 G

23 March 2021
Maciej Lata³³o

4. Image resolution

Our resolution test (resolution meaning the MTF50 function values) of Sony FE lenses is based on RAW files from the 42.4 Mpix sensor of the Sony A7R II or the 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 lenses have been able to exceed 70 lpmm. So far, two Sigma lenses have fared the best: the A 105 mm f/2.8 DG DN Macro (80.4 lpmm) and the C 65 mm f/2 GD DN (82.7 lpmm).

Let's see how the Sony FE 40 mm f/2.5 G compares – its results in the frame centre and on edges of the APS-C and full frame are presented below.

Sony FE 40 mm f/2.5 G - Image resolution

When it comes to the frame centre, the tested lens deserves to be praised. Already at the maximum relative aperture you deal with a high result, reaching almost 65 lpmm and on stopping down you can even exceed 75 lpmm. This performance is not as good as that of the Batis 2/40 and the Sigma C 2/35 (MTFs of both of them were a tad higher than 77 lpmm) but the Sony is a bit slower aperture-wise so its task was more difficult. Still it managed to perform very well, it's enough you compare it to other 2.8/35 class lenses. For example the Zeiss Sonnar 2.8/35 barely exceeded 62 lpmm and the Samyang 2.8/35 could get only as high as 63 lpmm.

Also the situation on the edge of the APS-C sensor should be assessed very positively. At the maximum relative aperture the lens is able to exceed 50 lpmm so it produces completely useful images. Maximum MTFs are reached in an aperture range from f/4.0 to f/5.6 and there you see very good values, of about 60 lpmm.

Please Support Us

The coronavirus crisis has been adversely affecting many businesses and, sad but true, ours is not an exception. Despite that difficult situation we would like to preserve continuity and high quality of publications available on all our websites. Still, we are now aware it might be impossible without additional financial help. That's why we would like to ask all those who visit, read, and care about Optyczne.pl, LensTip.com i Allbinos.com for support - it's enough you send us a small sum of money via PayPal. If a lot people decide to support our websites we think we'll stand a chance and survive next months without any lasting harm. We count on your support and understanding, stay safe and be healthy.

- - - - - - - - - - - - - - - - - advertisement - - - - - - - - - - - - - - - - -

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

When the constructors have to take into account the size of the lens, the edge of full frame is often troublesome. Also in this case you can notice some compromises connected to preserving right physical dimensions. By f/2.5 and f/2.8 the lens lands a bit below the decency level; fortunately on stopping down to near f/3.5 the problem disappears and from f/5.0 to f/9.0 MTF50 function values are on a really good level.

To sum up the Sony FE 40 mm f/2.5 G is a lens completely able to provide images that are sharp almost across the frame. There is a small compromise to be observed on the edge of full frame and at the maximum relative aperture but it's a price worth paying for smaller physical dimensions.

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, 40 mm, f/2.5
Sony FE 40 mm f/2.5 G - Image resolution
A7R III, JPEG, 40 mm, f/4.0
Sony FE 40 mm f/2.5 G - Image resolution