Lens review

Sigma A 50-100 mm f/1.8 DC HSM

26 April 2016
Arkadiusz Olech

4. Image resolution

The resolution test of the Sigma A 50–100 mm f/1.8 DC HSM was based on RAW files from the Canon EOS 50D camera. Maximum MTFs reached by the best lenses, attached to that body, amount to 52-55 lpmm. The decency level is situated near 34-35 lpmm.

First let’s check how the lens fared in the frame centre; the graph below presents appropriate results in a form of MTF50 function values we got at 50, 75 and 100 mm.

Sigma A 50-100 mm f/1.8 DC HSM - Image resolution

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It’s really difficult to find the right words in order to describe the results. The new Sigma is absurdly sharp. At the beginning of this chapter we wrote that the best lenses, tested on the 50D, are able to reach near 55 lpmm. In the shorter range of focal lengths the Sigma is able to go as high as them…being wide open! It is an incredible achievement, especially if you take into account the fact that you deal here with a zoom lens! What’s more, by f/2.8 and across the whole focal range the lens gets record-breaking results amounting to 59 lpmm. So far we haven’t tested a more outstanding device designed to work with APS-C/DX sensors…

Now let’s check the performance of the tested lens on the edge of the frame, presented by another graph.

Sigma A 50-100 mm f/1.8 DC HSM - Image resolution

No records here but it would be difficult to find even the slightest reason to complain. The performance is more or less even but you can notice a slight advantage of the middle of the range over the other focal lengths. What’s the most important, even at the maximum relative aperture the MTFs go as high as 42-44 lpmm so the images you get there are more than decent; in fact you can call them good. No weak points…

To sum up Sigma have proven once again that they are able to produce lenses which are not only unique when it comes to their parameters but also exceptionally sharp. A big round of applause!

At the end of this chapter traditionally we are presenting crops taken from photos of our resolution testing chart; they were saved as JPEG files.

Canon 50D, JPEG, 75 mm, f/2.8
Sigma A 50-100 mm f/1.8 DC HSM - Image resolution
Canon 50D, JPEG, 100 mm, f/1.8
Sigma A 50-100 mm f/1.8 DC HSM - Image resolution