All photos were shot raw and processed to correct camera-related inaccuracies such as exposure and white balance, without altering how the lens renders.
The forgotten macro
The Sigma 180mm ƒ/5.6 APO Macro UC is a rare and little-known macro lens from the late film era. Its main peculiarity, and one of the reasons why it didn’t make waves through the decades like so many legacy lenses did, is the very modest maximum aperture of ƒ/5.6, which narrows its shooting envelope and makes focusing quite tricky on SLRs. The other reason is that old Sigma lenses, as a whole, have bad reputation, and it looks like this particular model did not stay long in production.
Nowadays, electronic viewfinders and their focusing conveniences, as well as the need for small and light lenses for mirrorless cameras, can definitely give a second breath to this lens. The ƒ/5.6 maximum aperture is no longer a hindrance at focusing precisely and comfortably, and a long macro lens that is easy to carry in the field is refreshing. Internal focus is the icing on the cake.
When I reviewed the first photos I made with this lens, I immediately noticed the super clean rendition, both in the in-focus and out-of-focus areas, with a frame-wide clarity and well-defined focused elements. Considering the narrow wide open aperture, minimizing color errors is a requisite—with more defined defocused areas, these must be as undistracting as possible, ie. not plagued with color aberrations. It is definitely the case with this lens. Even though it is probably less of a challenge to create an apochromatic lens whose maximum aperture is ƒ/5.6, many optics don’t boast such a level of correction even stopped down to this value.
So how sharp is this old Sigma on a 42-megapixel sensor? Impressive at all distances over a large central portion of the frame, even wide open. Unlike close and medium distance shots, infinity requires ƒ/8 or ƒ/11 for corner-to-corner crispness, provided that you can nail the focus (more on this below) and that your combination of lens, adapter and camera allows at least near flat-field imaging. Although the Sigma 180mm ƒ/5.6 APO Macro UC is no slouch as a landscape lens, I think it shines most for close and medium distance shots wide open. It’s a rather clinical tool, and as a macro, it just delivers the goods. Beware the occasional veiling flare, that the lens hood appears to be helpless with, regrettably. By the way, global contrast is rather on the low side by today’s standards.
There’s a less obvious aspect of the ƒ/5.6 maximum aperture worth considering. With long lenses, in many close-up situations, stopping down is either a better choice or a downright necessity, both for better performance and to get more of the subject in sharp focus. This results in less smooth bokeh due to the shape of the diaphragm blades taking its toll in defocused areas—not only in “bokeh balls”, but with anything that has defined edges. With this lens, you get usable depth of field wide open and smooth bokeh in more situations than with other lenses of similar focal length. At medium distances, having less abstract out-of-focus areas is not necessarily a bad thing, just a different way to depict a scene. It gives more context to the viewer, yet with plenty of separation due to the long focal length, and some nice smoothness thanks to the fine optics and the wide open aperture.
In the end, the Sigma 180mm ƒ/5.6 APO Macro UC is a surprisingly high-performing, one-of-a-kind lens, and usually a bargain if you can find one in reasonable condition…
Out of the dark
Like many older macro lenses, the reproduction ratio goes to 1:2 only. The full 1:1 magnification can be achieved using a 2-diopter close-up lens like the Canon 500D. Even with IBIS, camera movement at close distances can be a sharpness killer at this focal length. With the Sony α7R Ⅱ, I’m not shooting handheld close-ups at less than 1/250s, but I’m not considering myself as particularly stable, so your mileage may vary.
If you start monitoring eBay and the like, you may notice that the Sigma 180mm ƒ/5.6 APO Macro UC exists in two versions: autofocus or manual focus. There are a few reasons that should goad you into seeking for an MF sample. Some AF versions have no aperture ring, so you may be stuck at ƒ/5.6, unless your adapter has contacts so the aperture value can be changed on camera. Besides, the MF version offers a much better focusing experience, thanks to a wider and smoother focusing ring. Not to mention that AF motors in old Sigma lenses are not mechanical prowess, so not having a part that may eventually break is always a good thing. Last, the dreaded “ZEN” finish (an awful plasticky material that always ends up leaking) seems to coat a larger portion of the lens on the AF version, compared to what I’m seeing on its MF sibling… and, yeah, less ZEN is better.
Due to the short throw of the focusing ring at non-macro distances, focusing for distant scenes can be very tricky. An extremely minute rotation can drastically change the focusing point, especially near infinity, and even at stopped down apertures, it makes a lot of difference. My particular combination of lens-adapter-camera allows focusing beyond infinity, so I can’t rely on the hard stop. If you’re shooting a landscape where you want sharp focus from say 100 meters to infinity, don’t focus on the most distant object you can see. Also, don’t rely too much on focus peaking for distant shooting, but magnify the viewfinder / LCD view as much as possible to nail the focus.
Which mount should you choose? Well, the lens is so rare that it’s unlikely you have a choice to make in the first place, so the question is more is the mount relevant?. For mirrorless cameras, the answer is not really, since adapters for all mounts are readily available. The Nikon F variant has the usual reverse Nikon focusing ring direction, and, well, that’s all you need to know.
Which adapter? While expensive ones from Novoflex and Rayqual are reliable in terms of build quality and tolerances, some much less expensive adapters are not necessarily worse. For instance, K&F Concept’s latest line of adapters (with a copper-colored ring near the mount) are much more affordable, and from what it seems, received a similar level of care in the design and manufacturing. They are sturdy, provide firm mounting, and feature nice touches like a matte inner finish to reduce potential issues caused by internal reflections—something hitherto only found on expensive adapters. The lens and adapter combo weighs about 500 grams.
Last, if not having lens-related info in the Exif data of your files bothers you, you can add them with the free Lightroom plugin LensTagger.
© 2020 Florent Chouffot, all rights reserved.