Review: Sigma 70mm 2.8 DG EX Macro
byon 12-03-2012 at 06:16 AM (1592 Views)
Macro lenses let you get close to your subject, and that's all they really are- lenses with short minimum focusing distances in relation to their focal length. There's a predictable set of focal lengths of macro lenses- ~60mm, ~1000mm, 150mm, and the higher-end 180mm. Sigma has one lens sitting outside of this pattern, making a 70mm lens, which sits in between the shorter 50mm and standard 105mm macro lenses.
Inside the Box
- Both caps (Sigma caps are okay, I prefer them to Tamron caps)
- Screw-in hood
- Serial number sheet
- Instruction manual (Explains their switches and bits)
- Pouch (I'll quickly forget about this)
It's happier to see you than you are it.
My copy of this lens has received the updated rubberized Sigma coating. Most on the used market will carry the older coating,which seemed to be quite polarizing in reception. I've handled an older copy, and while both seem about equally susceptible to permanent scratching, the anodized hood of the newer version seems easier to accidentally scratch off paint.
Interestingly, I've found that the version with the older finish stops down to a minimum aperture of f/22. The newer version goes down to f/40, which is actually a pretty big deal at the small DoF distances this lens works at.
This and the 50mm macro are the only macro lenses in the Sigma lineup that extend upon rotation; definitely a negative on the 70mm. The minimum working distance is a few inches, lessened further by the hood. When working near insects or something that may run away, I'd leave off the hood.
It should be pointed out that at the minimum focusing distance, the maximum aperture drops down to f/4.8, at the dismay of many users. This is due to the T-stops of the lens, not the F-stops, but for whatever reason, some lenses report their maximum f-stops instead, which is convenient for metering and retaining handholdable shutter speeds, but is not good practice for proper exposure. It appears that Sigma's 50mm macro retains f/2.8 at 1:1; how erratic the approach of the lens designers. I won't consider this as a fault since more lenses than not are this way, and you'd be a fool to stay at f/2.8 for serious macro work, but do be aware that f/2.8 is only achievable at infinity (4.5+ft).
The Sigma 70 bears a vey nice weight- 11.5oz. by my scale. It's not heavy enough for users to complain, like with a 24-70mm 2.8, but not so insignificant that it feels cheap, the Nikon 28 1.8G for example. I'm perhaps overtly critical of lenses when they're too light, and this one's gets a very happy passing grade.
The lens hood is a bit irregular- because the lens is externally focusing, and a significant amount of external protrusion at that, it's necessary to have the hood be screw-in. Interestingly, the front of the hood is threaded to accept standard 77mm filters, making it a convenient 62mm-77mm step-up adapter. However, because there's a good amount of space between the hood and the front element, you put a significant amount of air-to-glass boundaries, resulting in degradation of image quality; enough to visibly see unlike typical filter vs. no filter tests on the lens filter thread. I would still heavily consider picking up a proper step-up adapter if I were to consistently use filters on this lens. The hood is annoyingly irreversible for storage. This may be one of the few lens hoods I don't use religiously.
A bit of an oddity, there is no AF/MF switch on the lens. Therefore, you must toggle AF on the camera body, which can be a bit tedious depending on what body you pair the lens with. While this usually is not an issue, with macro lenses, you'll find yourself flipping to manual focus mode easily half of the time in order to get full 1:1 magnification.
How do you know how close up you are? Markers clearly delineate how much magnification is achieved at a certain focusing distance. Unfortunately, there's no way to tell if the full macro magnification is being utilized without taking your eye away from the viewfinder.
Pretty good actually.
With non-internally-focusing macro lenses, AF is often presumed to be cataclysmically slow, due to the extremely long focus throw. The Sigma 70 has a great path to travel; the focus ring rotates about 270° from near to infinity. However, it is screw-driven, meaning that the speed at which the lens focuses is dependent largely upon how good the camera body AF motor is; a bit of a double-edged sword. A focus limiter switch allows the lens to act as either a normal short telephoto lens that locks on as fast as any other lens, or a dedicated macro lens that focuses from only 0.257-0.48m. On a D800, because the throw between 0.55m to infinity takes only takes about a 30° turn, it focuses surprisingly quickly for this sort of lens. Very nifty indeed. Remember to turn on the limiter though; the full range of focusing takes almost four seconds.
Focusing, as you can imagine, is accurate; that's what all this long and winding focus travel path is for. The greatest limitation will be human forward and backward motion when being used handheld.
A hero among champions
Macro lenses are typically regarded as sharp; lens manufacturers rarely ever come out with soft lenses of this class. This typically great performance as standard makes it difficult to make a decision when comparing potential macro lens purchases. Somehow, the Sigma seems to be a small step above other macro lenses.
A few other macro lenses I've played with have shown slight signs of weakness wide open at maximum magnification. Others have shown a significant amount of chromatic aberration, which becomes magnified when shooting so close up. A few hiccups here and there. The Sigma 70 simply dances through all optical tests. I haven't been able to figure out a way to reveal flaws that are unique to it that another macro of this class wouldn't exhibit. I'm likely to keep this lens on absolute optical quality alone.
I plan to use the Sigma 70 as a normal lens at typical, non-macro distances, and see how they stack up compared to lenses like 85mm primes at infinity. Some lenes are good at some distances, and while it's a no-brainer that the Sigma 70 will be good close up, it's not guaranteed that it'll resolve well at long distances.
Chromatic Aberration- A bit of longitudinal CA can be found at times, but has been easily corrected so far. Very manageable. I haven't found significant lateral CA yet.
Distortion- I can't find even the smallest sliver of it.
Vignetting- Maybe a stop of corner shading on full-frame wide open, but easily corrected.
Flare- I will get back to this as I do more macro shots involving shooting flashes straight into the lens from behind a subject.
[++]: [+]: : [-]: [--]:
[++]Tier one image quality without having to think about where/when it's sharp
[+]Limiter does the trick for making it a typical-use lens.
[+]Very low levels of CA
[-]Occasionally hunts near macro, can take a while to lock macro distances
[-]Mediocre screw-in hood
[-]Atypical filter thread size