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Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions

12 January 2023
Maciej Lata││o

3. Autofocus and some remarks concerning optical properties

Image quality

Sample shots, presented in the last chapter, show clearly that image resolution is excellent in the range from 60 to 300 mm. When it comes to 400-600 mm focal lengths you can observe slight worsening but it's not clear why and the optics of the lens doesn't have to be the main or the only reason. Let me also observe that winter solstice in Poland is a very bad time to test telephoto zoom lenses – the weather is horrible, the transparency of air rather poor, the sun is hovering near the horizon, never getting to more than 15 deg even in the middle of the day...

Anyway the final assessment of the new Sigma's optics has to wait till we are able to test the final product. I also hope that, apart from the full resolution check, we will be able to get better sample shots.

Distortion

Lenses with high zoom factor, and the newest Sigma certainly belongs to that group, always have difficult times with correction of geometric deformations. Photos below show how the S 60-600 mm f/4.5-6.3 DG DN OS deals with that problem.

Sony A7R III, FF, JPEG, 60ámm
Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties
Sony A7R III, FF, JPEG, 200ámm
Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties
Sony A7R III, FF, JPEG, 300ámm
Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties
Sony A7R III, FF, JPEG, 600ámm
Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties


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As you see, it's pincushion variant everywhere and, as you move toward the longer end of the focal spectrum, these deformations tend to increase. At 60 mm you deal with a slight level of +0.5%, at 200 mm it increases to +1.4%, at 300 mm it is already +1.5% and at the longer focal lengths it amounts to +1.6-1.7%.

These values aren't very bothersome and, taking into account the fact that the task was difficult, you can say the Sigma managed to perform rather well.

Vignetting

Now let's check vignetting correction – below you can find photos we reached at maximum relative apertures of 60, 200, 400, and 600 mm.

A7R III, FF, JPEG, 60ámm, f/4.5 A7R III, FF, JPEG, 200ámm, f/5.6
Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties
A7R III, FF, JPEG, 400ámm, f/6.3 A7R III, FF, JPEG, 600ámm, f/6.3
Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties


As you can notice, the lens doesn't have any serious problems with light fall-off because its level doesn't exceed 2 EV at any given focal length. Results of 1.8-1.9 EV we obtained at 60, 400, and 600 mm focal lengths; a bit lower value, that of 1.5 EV, was observed at the 200 mm focal length.

Flares

When it comes to the performance against bright light, we feel the bar couldn't have been raised higher - in the case of the new Sigma you get as many as 27 elements positioned in 19 groups and it means as many as 38 air-to-glass surfaces where you can catch unwanted reflections. What's more, you also deal with a big front element that is not hidden inside the barrel very deep. The high zoom factor, autofocus, and image stabilization units mean it's rather cramped inside the casing; you don't get many places where apertures or ribs, helping to fight off reflections, can be installed.

It would be difficult to expect excellent performance so we are not especially surprised that we managed to catch quite a lot of light artifacts. As a kind of consolation you might add that these are present only when the sun is situated close to the frame corner and these aren't frequent situations while taking photos with this kind of equipment.

Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties

Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties

Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties

Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties

Sigma S 60-600 mm f/4.5-6.3 DG DN OS – first impressions - Autofocus and some remarks concerning optical properties

Autofocus

Sigma claims that their newest lens features the HLA motor which is supposed to guarantee a better focusing mechanism performance, with a faster, more accurate image tracking.

When joined with the Sony A7R III, the autofocus of the Sigma S 60-600 mm f/4.5-6.3 DG DN OS is completely noiseless. We didn't have any reservations when it comes to its accuracy and efficiency near the shorter end of the focal spectrum – the lens is able to cover the whole range, find, and confirm the focus in an excellent time of 0.3-0.4 of a second. The longer focal lengths are a different story, with focusing time amounting to 0.8-1.0 second. What's more, the mechanism sometimes wavered, as if not knowing the right direction. In situations with lower contrast the lens had a lot of slip-ups; while I was taking a photo of a sparrow sitting on a branch against a wall the autofocus often got lost, not being able to zero in on the proper aim even after choosing the smallest focus point that fit the sparrow very well.

Still, the producer explicitly states that the pre-production lens, with a beta version autofocus installed, doesn't feature final software. We do hope that the final specimen will be significantly improved in this area.