Review Sigma 105 Macro

17 October 2012

Sigma 105 mm f/2.8 EX DG OS HSM Macro & Nikon D3200

Although I am not a macro photographer, macro lenses belong to my favorite test subjects. That is because they are so very good, even in ordinary, non-macro, photography. The Sigma 105mm macro lens is quite unique because of the built-in image stabilization. Besides Sigma, Nikon delivers such a lens too, with the Nikon 105mm VR. Otherwise, there are not many macro lenses with built-in image stabilization. We previously tested the Sigma macro lens of this test on two Canon cameras (with full-frame sensor and APS-C sensor) and the Sigma SD1 Merrill. Now this Sigma macro lens is tested on a Nikon camera with APS-C sensor, the Nikon D3200 .

We test the performances of a lens on different cameras, because they are partly determined by the test camera. A chain is only as strong as its weakest link. The 24 megapixels and the in-camera correction of chromatic aberration of the Nikon D3200 offer this Sigma 105mm macro lens a chance to do its best.
On a camera with an image sensor of the APS-C frame, the Sigma 105 macro delivers a field of view with a full frame focal length equivalent of 160 mm. For macro photography of flowers or insects, you get a pleasant workable distance from the subject because of that. The combination of this longer focal length and a maximum aperture of f/2.8 enables you to limit the depth of field, enabling you to focus the attention toward the subject. The blurred foreground and background look nicely ‘woolly.’ The brightness of this Sigma macro lens is not constant however. With a reproduction ratio of 1:1, the brightness is f/3.8 instead of f/2.8. This is a normal phenomenon for macro lenses. Nevertheless, those who hold a true macro lens in their hands for the first time, might be surprised by it. Click on the image for a magnification.	Sigma 105 mm f/2.8 EX DG OS HSM Macro @ f/3.8
Construction and autofocus
The lens is made of a high-quality type of plastic, and the mount is made of metal. The whole feels solid and the focus ring turns smoothly without play. The lens includes a lens hood and a (compared to the Sigma 105mm lens) very spacious pouch. On the lens are switches for controlling image stabilization, choice between AF and manual focusing, and limiting the focus range. The latter is useful because macro lenses have a large distance scale. Limiting the focus range makes the camera focus quicker.	{insertgrid=289}
Nowadays, you do not often see a distance scale on the lens anymore. On this macro lens, you also see, besides the set distance in feet and meters, the scale at the top. The autofocus is of the HSM (“Hyper Sonic Motor”) type. Focusing is smooth and is virtually without noise. In low light, the Sigma SD1 Merrill camera rarely hunts.
Vignetting Sigma 105 macro
At full aperture, some vignetting of the Sigma 105 mm may be visible if you photograph a solid blue sky. However, a macro lens is generally used for a different subject and rarely at full aperture. In practice, you do thus not have to take vignetting into account when using the Sigma 105mm Macro OS on a camera with an APS-C sensor. Vignetting, expressed in stops, is very low at all apertures. Here you can see one of the benefits if you have a lens designed for full frame, used on a camera with a smaller sensor.
Image stabilization
In the current Sigma 105mm OS test, we have not tested image stabilization. In the test of the Sigma 105mm macro OS on a Canon 5DMK2, the image stabilization of the Sigma 105 mm OS provided about 3 ½ stops gain. That corresponds to the 4 stops that can be achieved with the enabled Optical Stabiliser function (OS) according to Sigma. With a focal distance of about 33 cm, the efficacy is approximately one stop. The image stabilization of the Sigma occasionally makes a grunting sound, even long after the image was taken.
Distortion Sigma 105 macro This lens has a flat front lens, making the resolution equal over the entire image field, regardless of the aperture. That makes the Sigma 105 Macro OS also very suitable for reproduction work. The distortion is extremely low too and will never be visible or disturbing.
Flare
In an earlier review with the Sigma 105mm macro OS on a Canon 5DMK2, we have already seen that the flare is not too bad in backlight. According to Sigma, this is thanks to Sigma’s SML (Super Multi-Layer) lens coating, which ensures that internal reflections and ghosting are suppressed. In addition, the SML lens coating ensures a neutral color reproduction. In the practice shots images taken with the Nikon D3200 , we have not encountered flare. In the studio, we saw a few prominent light spots when we took pictures with the Sigma 105mm macro very close to a bright light source. Such an extreme situation does not occur in practice. Nevertheless, it is an indication that internal reflections are not fully prevented in the design or construction of this lens.
Resolution Sigma 105 macro
Starting at full aperture, the resolution at the extreme edges is equal to the resolution in the center. That is a very good performance, which is more common in macro lenses. The maximum resolution is achieved after stopping down two stops. After that, the resolution decreases due to diffraction, but this happens so slowly that in practice shots, you see no difference between a shot taken at f/5.6 and f/11 in terms of resolution (disregarding the greater depth of field at f/11). Click on this image for a cropped image at f2.8 and f8.
Here are the results of our Imatest measurements for a Nikon D3200 jpg file, in which the resolution in the center is displayed with a blue column. The gray columns represent the resolution of the edges and the red columns show the resolution in the extreme corners. The resolution at f/8 is slightly lower in this graph than you would expect. You would expect the resolution at aperture 8 to be between the resolution of aperture 5.6 and aperture 11. We suspect this measurable, but not visible to the naked eye, difference is caused by the autofocus that was off a little at the test shots of f/8.
Bokeh
The Sigma 105mm macro OS has, thanks to the longer focal length and a brightness of f/2.8, a nice woolly blur in the background. The 9 diaphragm blades are not circular, so the bokeh is slowly changing from round to angular. At aperture 8, the bokeh is still beautiful compared to many other lenses, but the straight edges of the aperture are recognizable. Move your mouse over the image to see the difference in bokeh of the Sigma 105 macro at f2.8 and at f/8.
Chromatic aberration
We have measured the chromatic aberration of the Sigma 105 mm OS in jpg files. The chromatic aberration of the Sigma 105mm macro remains invisible at all apertures. That is not the merit of the built-in correction of chromatic aberration by the Nikon D3200 . It is due to the design of this lens by Sigma. Direct comparison of jpg files to RAW files, at a magnification of 100%, both exhibit no trace of visible chromatic aberration in the corners. That is a top performance.
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Conclusion Sigma 105 mm f/2.8 EX DG OS HSM Macro review

WYSIWYG score: This table shows the performance of this lens if you store the files in the camera as jpg, where you have all available in-camera lens corrections applied. This score gives you for this lens/test camera combination: “What you see is what you get”.	{insertgrid=308}
Pros Excellent optical performances: high resolution, very low distortion, chromatic aberration and vignetting Constant resolution over the entire field Beautiful wooly display of blurred parts Built-in image stabilization	Cons The pouch is relatively large compared to the lens High price
The Sigma 105 mm f/2.8 EX DG OS HSM Macro is designed for a camera with a full frame sensor. In terms of optical quality, this is a very good lens, which performs very well on a modern camera with an APS-C sensor as the Nikon D3200 in this review. The Sigma 105 Macro OS also very suitable for reproduction work, since the corner sharpness matches the centre sharpness at all apertures.