Did you ever think that your standard 17-50 (or similar) lens has a too large zoom range, weighs too little and is too cheap? Surely not. So why would you want to have a massive 18-35mm lens that costs around 750€? Sigma must be nuts to develop such a thing!
Two reasons: aperture and image quality. It’s that simple.
Long Story first – skip if you just need technical details.
I first tried the Sigma 18-35mm f/1.8 DC HSM Art in Dublin on holiday. After a few test shots the autofocus appeared to be a hit and miss so I played it safe and decided not to buy abroad.
Back home I went to my local dealer and spent a long time trying their only remaining model. The result was so-so even on a 7DmkII and 750D that they had on display. But as they had all lenses on sale for 10% off that day I jumped right in and bought it.
What do you do with a new lens? You walk around and shoot random things, learning how your new toy behaves in the real world. Disillusion came quick as I realized that the focus was off at many distances that I had not tried in the shop.
So I went back, ready to get an instant refund. The good man at the shop however convinced me to give it one more chance and let him send it to Sigma for calibration. So after an agonizing 6 weeks (they forgot to send the proof of purchase) I went back, tried it and oh wonder suddenly it was focusing perfectly at the distances that were terrible before.
Some days later I had time for some testing and instantly I regretted ever getting the lens. The focus was now way off at the distances that were perfect before! This time I decided to contact Sigma directly via eMail. The response was quick and nice and they asked me to send the lens and camera in again promising to return all before christmas. I got a for for a free return with DHL and off it went.
Wondering how long this may take I was extremely surprised when 3 days later I got a packet back.
The result? Oh well… I was SO frustrated to find that trying to focus on my self-printed test target was horrible at 18mm and a distance of around 1-1.5m.
What now? An email with no so happy words was prepared to go, I went through loads of websites where people seemed to have similar problems but they solved them by calibrating the lens themselves with the Sigma USB dock. But I had the lens calibrated twice by Sigma themselves! Why should I invest even more time and money to make the lens work?
Oh well, the dock can be returned and I really want the lens to work so I will just give it one last try.
Hours of adjusting and testing later all focal lengths were adjusted at all possible distances. Especially the infinity setting had to be heavily corrected.
And the result of all this? Let me put it like this: The focus itself is far from perfect and hopefully Sigma can improve it via firmware update in the future but in the real world it works really fine. Not always perfect but most of the time.
Now let’s get to the technical details.
The lens is a massive piece of equipment. Compared to the Tamron 17-50mm f/2.8 it not only looks huge. It’s almost twice the weight (852g according to the kitchen scales) and with the hood off it is as long as the Tamron with the hood on.
The filter diameter is reasonable at 72mm and there is no restriction for using filters like bulbous front elements or similar.
What stands out even more than the size and weight is the high quality feel when holding it. Sigma has really outdone themselves with the latest lens design of the Art-Line lenses. The Plastic feels almost like metal, focus and zoom rings are perfectly damped, the AF switch clicks nicely and of course there is no wobble at all.
One thing that I always hated about Canon lenses is the lack of accessories that come with the lens as standard. On non-L lenses you don’t even get a lens hood as standard and bags are not nice and padded but mostly simple pouches. Sigma supplies you for free with a nice bag and a lens hood that is unparalleled (as far as my knowledge of lenses goes).
There is no movement when zooming or focusing. Everything happens inside the barrel.
Enough for the external view. How does it look on the inside? The optical construction is very complex with 17 elements in 12 groups. That’s of course what makes the lens heavy and big.
Chromatic aberrations are low, vignetting is well controlled, distortion is ok and not really relevant in everyday situations, AF is really fast, coma is good.
What is most important: the images produced are incredibly sharp at all apertures and focal lengths. Images at f/1.8 are already sharp and contrasty across the frame. Stopping down improves corner quality and overall detail a bit but mainly it reduces vignetting.
18mm@f/1.8, 100% crop, no adjustments
18mm@f/4, 100%crop, no adjustments
One important aspect of large aperture lenses is the background blur or “bokeh”. The question whether the quality is good or not depends very much on your own taste.
EOS 7D – ISO100 – 1/1000 s – f/1.8 – 18 mm
EOS 7D – ISO100 – 1/1600 s – f/2 – 18 mm
For me the Bokeh is very nice but not perfect. Highlight are nice and circular but not as creamy as you are used to from f/1.8 prime lenses.
Sigma has created a unique lens with the 18-35mm f/1.8 DC HSM Art that makes things possible that one could only dream of before. 18mm f/1.8 lenses were not even available as prime lenses and they managed to put in zoom and astounding image quality as well!
Optics and build quality are up to highest standards and combined with the reasonable price (around 700€ in Germany in November 2015) the value for money is amazing.
The focus issues are something to worry especially for those who do not want to invest hours of work for calibration. Especially the fact that two trips to the Sigma service center did not really help makes me wonder what they are doing. Better calculate 40€ for the USB dock when looking for the lens.
So in the end there is a lot of good stuff but it is hard to overlook the focus calibration issue.