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This review is about the old version of the lens – Sigma 105/2.8 EX Macro and its performance on an APS-C camera (Canon EOS 40D). The current version (Sigma 105/2.8 EX DG) shares the same construction but has an improved lens coating that reduces reflections from the sensor. Hence the DG (Designed for digital) in it’s name. This is a full-format lens so it is still usable on film SLRs as well. On APS-C DSLRs, the lens field of view is equivalent to that of 168mm focusing distance on full-frame cameras. The primary application of the lens is, obviously, macro photography, but it’s not limited to that – infinity focus is possible.

The widest aperture is f/2.8, at which it is fully usable.

f/2.8, 1/125, ISO800 (100% crop)

For macro purposes, I usually use f/8, rarely f/9, to gain more depth of field without entering the diffraction zone at smaller apertures. Besides this, according to the photozone.de MTF charts (concerning the DG version), the max sharpness is at f/8, which pleases me. Another reason to not use smaller f-numbers than these is that I always use the lens with extension tubes, sometimes tele-converter, which leads to even smaller effective f-number.

f/9, 1/250, ISO100 (Macro setup) (100% crop)

When shooting landscapes, I use at least f/8 to achieve sufficient depth of field.


f/8, 15″, ISO100 (100% crop)

For portraits, I usually use at least f/3.2 to gain more sharpness and confidence that I’ll have enough depth of field.

f/3.2, 1/160, ISO100 (100% crop)

The minimum aperture is f/45, but you probably won’t ever use it. There are 8 aperture blades, giving a very pleasing and unobtrusive bokeh, especially when shooting portraits.

f/3.2, 1/160, ISO160 (100% crop)

The minimum focus distance (from the sensor plane to the object) is 31 cm. In this case, the effective working distance (from the front edge of the lens to the object) is 12 cm, giving 1:1 reproduction ratio. I.e. 22.2 mm fill the frame of an APS-C camera horizontally, and respectively, 36 mm for a full-frame camera. Combining the lens with extension tubes and a tele-converter is more interesting to me, but I’ll write another article about this.

As you can read in the reviews on the Net, the distortion level is negligible which is quite normal for a prime lens. Vignetting is reduced to minimum, and, according to the laws of physics, decreases with smaller apertures, so it is not to be worried about. You would hardly notice any chromatic aberrations on your photos. I rarely manage to cause them, but even then, their size is insignificant.

f/4, 1/250, ISO200 (100% crop)

When there are CAs in macro shots, they’re usually in the diffuser’s reflection in something in the frame, but after all, as I already said, I always use extension tubes, which is a precondition for additional degradation of image quallity, even if minimal.

f/8, 1/30, ISO100 (Macro setup) (100% crop)

The weakest side of the lens, in my opinion, is the speed of autofocus. Naturally, this may bother you only when you’re not shooting macro. In this case you can use the focus limiter to reduce the lens hunt.

For macro purposes, you would usually prefer using manual focus, whether you use the focusing ring or move the camera back and forth to position the focus plane where you want it to be. Besides being slow, the autofous is also a little bit noisy. Interesting thing here is the Dual-Focus (DF) mechanism. It allows you to decouple the focus ring from the focusing gear by pushing it forward. This way, during autofocus you don’t have to worry where you’re holding the lens.

Another disadvantage of the lens is the fact that it’s length grows when focusing towards closer distances. To get 1:1 reproduction ratio the front element protrudes by approx 5.5 cm.

On the other hand, the front element resides 2 cm behind the outer edge of the lens.

This makes it difficult to clean but also hard to scratch and stain when shooting in the field. It also doubles as a lens hood. I consider this an advantage over the fixed length of the Canon EF 100/2.8 Macro, which is easy to scratch, because its front element is unprotected. Not being an internal focusing lens, the Sigma 105/2.8 EX Macro is supposedly predisposed to easily collect dust, but I have no such complaints.

The construction is solid with the typical Sigma EX (“Excellence”) finish. The focusing ring operates very smoothly and is well damped. Of course, the lens mount is metal. With its weight of 460g and a size of Ø74 х 95 mm (at infinity focus), it is pretty compact. The filter thread is 58 mm and the front element doesn’t rotate, so using a polarizer wouldn’t be a problem.

The package includes a case and a lens hood, but you are unlikely to use the latter often. As I said, the front element is deep enough behind the front edge of the lens, so the hood would additionally decrease your working distance. It mounts on the filter thread, not on a separate bayonet, so you could mount a CPL filter and the hood on top of it without a problem. The hood also has a 77 mm thread, which can also be used to mount a filter or a lens cap.

Conclusion
I’m fully satisfied with my purchase and I don’t think I will replace it with any of its direct competitors in this focal length group (90-105 mm) anytime soon. I haven’t tried any of them, but I don’t think they could offer much more to justify the higher price tag. Besides, its weight is of exceptional importance to me, because I often use extension tubes, tele-converter and a flash unit which makes the setup rather heavy.

Comparison table of 90-105 mm Macro lenses

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