Image: Shooting so close gives a very shallow depth of field, but thankfully the out-of-focus bokeh is soft and smooth
For our resolution chart images, the Sigma 180mm f/2.8 macro lens was paired with a 21-million-pixel Canon EOS-1Ds Mark III. Its performance was very impressive, resolving up to around 30 on our chart.
As you would expect, the results are sharpest at around f/8-f/11, but even at f/2.8 the lens still resolves plenty of detail and it is more a loss of contrast that gives the impression that detail has lessened. At f/16 and f/22 there is a slight drop in both resolution and contrast. This is common in all lenses, as refraction starts to take effect. However, it is particularly significant with
a macro lens as the depth of field is so important. At the 47cm minimum focus distance, and using a Canon EOS-1Ds Mark III, the depth of field is around 40mm at f/16 and 57mm when at f/22.
As this is a fixed telephoto lens, barrel distortion is not an issue, although there is a slight pincushion effect. As a lens of this focal length will not be used to photograph architecture, the slight distortion should be of no concern and it is very easily corrected.
It is a similar story with vignetting: unless really looked for, or photographing a completely solid background, it shouldn’t be too noticeable, and certainly nothing that would degrade a macro or wildlife image.
The lens does produce red/cyan chromatic aberrations, but these are very slight and only really visible on close inspection of the image at 100%. As usual, such distortions are easily removed in Adobe Camera Raw.
Overall, the Sigma 180mm f/2.8 lens is a very good macro optic, on a par with the Sigma 105mm f/2.8 macro lens we use for all our camera resolution tests.
The images below show a small section of our resolution chart. All the images in this test were taken with the Sigma APO Macro 180mm f/2.8 EX DG OS HSM lens and a Canon EOS-1Ds Mark III, which has a full-frame, 21-million-pixel sensor. The results are on par with the Sigma 105mm f/2.8 Macro lens, which is our standard lens for testing camera sensor resolution.
To see a large resolution chart, click here