Tuesday, January 22, 2013

Tokina AT-X PRO DX 12-24 F/4 Review

The AT-X Pro DX 12-24 F/4 is one of Tokina's two entries into the APS-C ultrawide zoom category, the other being the more popular 11-16 2.8. Plenty of other competitors round out the category from both first and third-party manufacturers so I recommend checking those out as well to help you make your decision. This lens differs from the rest in that instead of starting at 10mm like almost all of its brethren, it begins at 12mm but goes all the way to 24mm on the tele end, allowing it to extend into 'normal' lens territory and compliment the 24-XX zooms very well. The lens in the following review was tested on a Canon 50D, 20D, 350D, and 5D (that last one wasn't a typo), and was purchased for $450 retail in 2012.

Note that there's now a 'II' version of this lens, which is optically identical to the version reviewed here. The only difference between that and the original is the inclusion of an in-lens motor for the Nikon mount version and 'improved lens coatings', which I get the feeling is a marketing placebo to justify the new version for the other mounts.
12mm @ f/9 - I bet nobody has ever photographed this place before
My impression upon picking the lens up for the first time was just how solid it looked and felt. Made of high-quality textured polycarbonate, the lens is very tightly assembled and devoid of any unwanted movement from the zoom or focus rings and has a fair heft for its size. Both focus and zoom rings turn very smoothly and have a good amount of travel. Since the lens uses internal focusing, its physical length does not change while zooming or focusing, though the inner barrel moves back and forth slightly. Other features include a focus distance window (without infrared or DoF markings), an included petal-shaped lens hood, and a 77mm centre pinch cap. Strangely, Tokina uses a green line to denote where to mount the lens on the body, but it must be inserted at the 10 o'clock position instead of 12 or 1 of the usual red dot/white square. After nearly a year of ownership, this still trips me up every once in a while.

Utilizing a conventional DC motor instead of the ultrasonic motors of Canon, Nikon, and Sigma competitors, the lens lets off a rather high-pitched whine while focusing, though it isn't loud by any means and is inaudible from more than a couple feet away. Despite not having an ultrasonic motor, AF remains fast in low light though not quite at the same speed as a ring USM or HSM. In lower light AF slows down noticeably to about half its normal speed yet it doesn't hunt at all - accuracy seems to be preserved. Another key disadvantage of not having an ultrasonic motor is the lack of manual focus override - you have to be in manual focus mode to do so. Speaking of manual focus, this lens does away with the traditional AF/AF switch that nearly all other lenses use and instead uses a clutch mechanism that's engaged by pulling the entire focus ring toward you. In theory this seems like a much faster and easier way to switch between focus modes but in practice it takes far more force than it should to activate, and requires an entire hand to do so, instead of the single finger one would use on a traditional switch.
12mm @ f/8. Sometimes you'll wish for 10mm on the wide end.
Image quality from the Tokina 12-24 ranges in various aspects. Sharpness is pretty good throughout the focal range wide open in the centre, and tails off slightly into the edges of the frame. Sharpness improves noticeably when stopped down to f/5.6, though oddly enough stopping down to f/8 or f/11 yields diminishing returns. Vignetting is present wide open but it's not terribly intrusive, and is lower than the Canon 24-85 and 50 1.8 exhibit wide open. Distortion is also fairly low, at least in the image centre. While low on barrel/pincushion distortion, the edges of the frame will show any buildings or square objects to racked and stretch, as with most ultrawides. Fortunately the distortion isn't terribly complex and is easy to correct. Shown below is a quick newspaper sharpness comparison taken with an EOS 50D at 24mm (resize of original image):

Optical weaknesses of the 12-24 are best seen in backlit scenarios, where rather heavy chromatic aberration rears its ugly head. Not just in the corners, either, but throughout the whole frame and at all focal lengths. It's easy enough to remove in Photoshop. Every now and then flare issues appear, though normally only in long exposures where artificial lights hitting the lens at certain angles will prove problematic. Unfortunately protection against this is going to prove difficult since the included hood is about as large as it can be without being visible in the frame, so it's something to keep in mind if shoot in these situation often.
CA viewed at 200% @ 12mm
As alluded to earlier, third party APS-C lenses have one small advantage over Canon EF-S glass, and that is in the ability to actually mount on a full-frame body, something an EF-S lens can only do after some modification. While this is of very little practical use, it is a cool novelty and when used on a 5D or other full-frame body it covers the entire image circle from 18-24mm (and sadly it performs better than the EF 24-85 at 24mm). Below 18mm vignetting gets really heavy because of the small image circle, so you get images that look like they came from a circular fisheye lens. Shown below are samples of the Tokina 12-24 on an EOS 5D, showcasing the 'damage' from hurricane Sandy.

Useful? No.     Fun? Yep
Ultimately, the Tokina 12-24 f/4 is great lens that, at least in the EF mount, is unique in its focal length range and constant aperture ability. It's a fantastic all-rounder with a sturdy build quality and generally good optical results that have prevented me from wanting a 17-40L. The only real bringdowns are CA, flare, and the lack of an ultrasonic motor. Luckily for you, there's plenty of competition out there to choose from, so make sureyou check all of those out before deciding if this lens is right for you.

The Good

  • Sharp wide open, improved further by f/5.6
  • Excellent build quality and solid feel
  • Fast AF in good light; accurate AF in any reasonable light
  • Low distortion for an ultrawide
  • Nice, deep hood (relative to competition)

The Bad

  • Chromatic aberration very strong 
  • AF slows down noticeably in low-light
  • No full-time manual
  • Clutch AF/MF switch too tight
  • Occasional flare issues

Update May 19th, 2013: My 12-24 has developed an issue where attempting to stop down the lens at focal lengths between 12 and 15mm will result in Err 01 on the camera. Even pressing the DoF preview button won't stop the aperture down, and it happens on all of my bodies. For more details, it's identical to what's described in this post on photozone.de. I'll most likely have to get it serviced, I'll update later and let everyone know how that goes.

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