The Sigma 180mm f/2.8 DG EX OS HSM Macro is not a mainstream macro lens. It is a specialized tool that one acquires with specific goals and purposes in mind, like getting the most diffused out-of-focus areas, taking advantage of a long working distance, or avoiding most of the background distractions by virtue of the narrow field of view.
Usefulness of f/2.8
An aperture of f/2.8 is not often used in macrophotography, and compared to the previous 180mm f/3.5 Macro design, the increase in size and weight with the 180mm f/2.8 OS Macro is dramatic. So what is the interest of f/2.8 here?
A large aperture is useless on a macro lens is a comment often seen from dim-witted photographers. After all, these lenses (most of) also offer the possibility to focus all the way to infinity, right?
Actually, increased size and weight (yes, and cost) are the only drawbacks to a wider aperture to me. The pros are:
- Brighter viewfinder
- More room to work before diffraction kicks in
- Use of faster shutter speeds, which is useful in some cases (any moving subject, dim light)
- Better subject isolation (portraits, and anything shot at medium-distances)
- Creative effects in general, even at macro distance
All in all, it allows the user to benefit from the great optical performance that comes with such a lens in more situations.
Two OS modes are available on the Sigma 180mm f/2.8 Macro OS. “Os 1” compensates for movement along both the horizontal and vertical axes, whereas “OS 2” takes only the vertical axis into account (useful for panning). “OS 1” was used here.
Pressing the shutter button halfway activates the OS. A little noise can be heard, and the viewfinder stabilizes, making framing easier.
Sigma rates the effectiveness of the Optical Stabilization incorporated in the 180mm f/2.8 Macro OS at 4 stops. So, theoretically, the user should be able to get a sharp image handheld at around 1/10s-1/15s.
Sigma also specifies something important, especially when dealing with a macro lens:
The OS effectiveness will gradually decrease as the shooting distance becomes shorter.
This is due to the user-induced shaking effects increasing along with the magnification, and being particularly strong at 180mm to begin with.
The following test shots show what it is like in practice, both at distance and up close. Overall it should be quite faithful to what a user with no exceptional steadiness skills can expect.
Click on “Compare images” to switch between the crops.
Optical Stabilization at distance
Sigma’s claims are underpinned by field shots. The stabilization feature of the Sigma 180mm f/2.8 Macro is proving its efficiency with such a scene.
When shooting a distant scene handheld, my keeper rate is good until as low as 1/10s. This is about 4 stops of improvement, an impressive result given that the equivalent field of view of the lens is 270mm when used on a Sigma SD1 Merrill.
Optical Stabilization up close
At 1:2 life-size, my keeper rate becomes good at 1/50s. That is about 2 stops of improvement.
Beyond this magnification, I would use a tripod for pin-sharp results if light is lacking.
Optical Stabilization on tripod
It is advised to turn optical stabilization off when the lens is mounted on a tripod, due to the total lack of movement fooling the stabilization algorithm.
As you can see, the results sustain this advice.
Four stops of improvement can be expected in the best case. At least this is congruent with what Sigma announces. Sometimes, manufacturers are a little too optimistic, but not here.
The usefulness of OS will be driven by your use of the lens, but having a steady viewfinder is always comfortable. It is quite delightful when the lens is used as a telephoto, less so but still helpful for close-up photography, which happens to be the chosen field of this lens.
Tripod or not tripod?
In the field, at one time or another, there is always a situation where a tripod-less photographer thinks: here, a tripod would have helped.
The stabilization featured in the Sigma 180mm f/2.8 Macro can definitely reduce the occurrence of this thought, but an issue become even more prominent when it comes to macro shooting. An issue calling for a tripod!
Aside from the reduction of OS effectiveness shown above, there is no way the OS can compensate for the photographer’s movements that put the plane of focus in front or behind the subject. This is a frequent problem in photography and even more in macrophotography, where a very slight movement of the photographer is enough to kill the shot.
The above setup weighs at about 2.5kg (5.5 oz). Tripod manufacturers are often a bit optimistic about the weight capacity of their gear, so be careful when choosing/using yours. A look in the viewfinder should let you know about the steadiness of your setup.
Sigma supplies a removable metal tripod collar with this lens. It is rather well-made and adjusts easily. However, a longer plate would be nice considering the front-heaviness of the Sigma 180mm f/2.8 Macro OS, and a longer neck would allow the lens to be held from the plate.
Minimum focusing distance
One of the reasons to choose a 180mm macro lens over a shorter one is the minimum focusing distance: the distance from the sensor plane at which full magnification is obtained.
Sigma indicates a minimum focusing distance of 47 cm for the Sigma 180mm f/2.8 Macro OS. This is about 15cm more than with a 100/105mm lens. However, a 180mm f/2.8 lens is much longer than a 100mm f/2.8 lens. So, is the longer MFD really useful for practical use?
The effective working distance, from the end of the lens, is about 21.5 cm (8.46 in). That gives about 3 cm of extra distance versus a 100mm macro lens like the Canon 100mm f/2.8L Macro IS USM.
When taking pictures of shy critters, you may want to leave the 9-cm lens hood out of the equation, to prevent your subject from running or flying away. Also, the hood will create a shadow on the subject if a cobra flash is fired at minimum focusing distance.
The effective working distance is at its lowest with the extra hood portion that Sigma supplies for use with APS-C cameras (not shown here).
In fact, the MFD found in the specs provided by the manufacturer only tells at which distance the photographer can be when focusing for full magnification. An extrapolation must be made from this value, by taking the size of the lens into account, so as to get the effective working distance that is so relevant for field use.
Want more working distance? Grab a teleconverter.
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