When Sigma announced the release of the worlds fastest zoom lens available, the photography world stood by and waited. When they announced that it was for crop bodies only, they were let down. When sigma announced the price was sub $1,000, they became idolized. But, with all this hype, does the lens live up to expectations? Do the empty shelves, and backordered request live up to expectations?
When DxOMark released their latest numbers on the new Sigma (canon mount) 18-35 F1.8 it was rated at the time (and still to this date) the sharpest, and highest rated lens on a crop sensor body. While it may seem like this is an ultra wide lens (18mm on the widest) we have to remember that this is before the “crop factor” has been put in place. On a canon APS-C sensor, you will yield an effective focal length 28.8mm – 56mm, this falls just shy of replacing the full frame 24-70mm, and does not compliment either ends of the spectrum. So where does the hype come from? Perhaps its because on a crop sensor, the f1.8 zoom will give you the “look” of a f2.8 lens in terms of performance, but give you an extra stop of light in order to keep your ISO lower on these poorer performing bodies. This means better quality low light videography, and photography. Mounted on a 70D this lens is quick, smooth to focus and zoom, and provides excellent quality in regards to both video and stills. But with a price tag retailing at 799 USD, can one justify buying this crop sensor only lens? Let’s look at how it performs on canons 1.3x Sensor pro-body (APS-H), the EOS 1D Mark III.
Because the APS-H sensor has a 1.3x crop factor, the thought would be vignetting should be less, if at all, across the zoom range, and possibly nonexistent around 24-35mm range. In order to test vignetting, I used the 1D mark III attached to the sigma and brought a pure white backing into sunlight and shot directly at the white board. This of course exaggerated any (if any) vignetting to give the best example. Let’s examine the results, all images were shot with the same exposure: F4.0, ISO 200, Shutter 1/8000. No hood was in place, only a B+W MRC Pro UV Filter.
Vignetting seems to disappear around 20-22mm with only slight edge vignetting visible at 21mm in our test. From here it seems like vignetting is pulled very well under control until you get closer to the tele end where slight vignetting returns at 35mm. The further you stop down with this lens on your body, the more exaggerated this effect will be seen, giving possible unusable results at the widest end, and possible only becoming clear of vignetting around 23mm till 32mm, where it returns slightly. Whether these results are acceptable to you or not, will vary with need. Many users who have pro bodies, will more than likely already have a plethora of glass in this range, including many primes. The idea of this lens is to provide a constant prime like aperture across a usable zoom range, while maintaining sharpness across the frame. One must consider that since this is made for an APS-C sensor, the edge sharpness will suffer when used on a larger sensor. It’s easiest to maintain sharpness across the frame when using APS-C sensors, simply because the sensor is looking at the best section of the glass only.
Verdict: If you have an APS-C body (7D, 70D, SL1) and need a fast zoom lens to replace some of your primes, (28, 35, 50), this could be your goto solution. Images taken on the 70D are crisp, clean, and beautifully rendered. If your main body is a canon APS-H proline, and you keep a 7D as back up for your wildlife scene, and are interested in getting a zoom lens for lower light photography where you don’t want to push that ISO too high, again, this may very well be the lens for you. However, if your main bodies are Canon Full Frame, and APS-H pro bodies, and you do not have a crop sensor body, the choice will vary per individual. Knowing that 18mm is only usable with slight vignetting and 35mm as well, it’s a trade off game you will ultimately play. For 800 USD you can get an 85mm F1.8 and 50mm 1.4 and still have some money left to put toward a used 20mm F2.8. All these lenses will perform on all your bodies (Crop, Full Frame, APS-H) and will give you the beauty primes are known for. If you want a single lens to replace these primes, this will do it for you on an APS-C body, but for the APS-H it could be yes it could be no. If I personally didn’t keep an APS-C camera around, I would have a hard time justifying keeping this lens around. But for the time, it generally stays locked onto my 70D.
All in all I highly recommend this lens be added to your bag if. . .
1) You have an APS-C Body
2) You shoot in low light
3) You want to shoot video in low light
4) You have an APS-H body, but also an APS-C as a backup and do not have a 24-70 F2.8
Feel free to send questions and sample requests in the comment section below.
I have also received some request regarding full frame performance with this lens. While I won’t go into a lengthy write up to say what 5 pictures can illustrate. Here is the lens mounted on my 6D undergoing the same test, the shots were performed at ISO 400, f8 1/30 of a second on a tripod.