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Sigma 150-600mm f/5-6.3 DG OS HSM | Sports (Canon EOS) - Review / Test - Analysis |
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Lens Reviews -
Canon EOS (Full Format)
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Distortion
The Sigma lens produces pincushion distortions throughout the zoom range. The amount is very low (0.3%) till 450mm and increases only a bit at 600mm (0.6%). By most standards, this is rather negligible.
Vignetting
Vignetting is visible at maximum aperture throughout the range. It's most pronounced at 150mm f/5 at 1.8EV (f-stops) and slightly less so at longer focal lengths. Stopping down to f/8 pushes the light falloff below 1EV, especially at the wide end. At f/11, you may still spot a little vignetting at 600mm but otherwise, it's negligible.
MTF (resolution & chromatic aberrations)
Some may be surprised by the relatively moderate performance figures below. Please note that two effects are coming together here. First of all, the "common" peak performance on the EOS 5Ds R, our test camera, is reached around f/4. The Sigma lens is slower than that thus, diffraction effects are already decreasing the resolution potential at all aperture settings. On top of that comes the fact that we are talking about a super tele lens here. Remember that this is a chart-based MTF system, and the longer the focal length, the longer the distance between camera and chart. Beyond 300mm, air diffusion is starting to have an impact, and as you can conclude, it's correspondingly more pronounced the more you zoom out. Please keep that in mind here.
The Sigma lens is capable of delivering a very decent performance throughout the range, albeit with a few hiccups (on the EOS 5Ds R @ 50mp).
The center performance is excellent at 150mm and decreases slightly the more you zoom out. However, the center - and near-center - is still very good straight from the max. aperture even at 600mm. The borders are usually good except at 300mm, where they reach very good levels. The extreme corners are a bit soft at 150mm and 600mm but better in the middle range. The global peak performance is around the 300mm mark.
The centering quality of the tested sample was very good for such a lens.
Please note that the MTF results are not directly comparable across the different systems!
Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure of sharpness.
If you want to know more about the MTF50 figures, you may check out the corresponding Imatest Explanations
Chromatic Aberrations (CAs)
Lateral chromatic aberrations (color shadows at the image borders) are very well controlled between 150mm and 300mm. Beyond, they increase a bit but remain unobtrusive.
Bokeh
The max aperture of the Sigma lens may be moderate, but a shallow depth-of-field is still easily possible at longer focal lengths and medium focus distances. So let's have a look at the bokeh.
Out-of-focus highlights are pleasing if they are sufficiently "big", but once they compress, they show a ring substructure that is getting pronounced the more you stop down. This is not unusual - we've seen a similar characteristic in the Tamron 150-600mm f/5-6.3 as well as the Sony 70-400mm f/4.5-5.6.
As usual, you'll also have to live with "cat's eyes" at the image borders - shown below at 500mm f/6.3.
As far as the general out-of-focus blur is concerned - the background is quite smooth (left-hand sample crop below), a bit less so in the less critical foreground blur (to the right).
Bokeh Fringing / Longitudinal Chromatic Aberrations (LoCA)
The so-called bokeh fringing refers to colored halos in the focus transition zone. Hard contrasts can have a purple color tint in the foreground, changing to greenish beyond the focus point. However, this aspect is mostly an issue for ultra-large aperture lenses and the slow speed Sigma isn't really affected by this even at max. aperture.
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