Introduction

Sigma 14mm f/2.8 EX ASPH HSM was the widest prime angle lens in Sigma's lineup. Unfortunately, the company discontinued manufacturing the lens circa 2007, although new copies of the lens are still available as new old stock at some photo retailers at ~US$800. Old copies of the lens are also pretty common on used markets and sell for ~US$700 (as of April 2008). While not necessarily cheap, the lens was still priced quite aggressively compared to the OEM 14mm lenses from Canon, Nikon and others. The lens was available in several mounts, including Canon, Nikon, Sony/Minolta and Sigma.

The optical construction of the lens consists of 14 elements in 10 groups. The optical formula incorporates aspherical elements, designed to correct various forms of aberration. The build quality of the lens is excellent, rivaling that of any of Canon's L pro-grade lenses - the barrel looks and feels very sturdy, with no wobbling inside or out. The focusing ring is rubberized and rotates with ease. The ring is pretty wide and is comfortable to grip. The barrel has matte finish and is scratch resistant.

Sigma 14mm f/2.8 EX DG ASPH HSM sports a fully automatic aperture control mechanism, so there's no dedicated aperture ring and aperture settings have to be controlled directly from the camera. Sigma included an HSM (Hyper Sonic Motor) type AF as well as fully manual focusing system that can be controlled using an AF/MF switch on the side of the barrel. Sigma detached AF operation from the focus ring, so it does not rotate during auto focusing - you can still rotate the ring to fine-tune focusing after the AF narrowed-in on to a target.

Image

The lens is pretty compact and light, measuring 80 x 91mm (3.15 x 3.6in) and weighing 655g (23.1oz). The minimum supported aperture is f/22 and the minimum focusing distance is 18cm (7.1in). The front element is a chunky piece of glass, bulging out of the front of the lens. And while Sigma incorporated a built-in petal shaped lens hood which is cut out on the sides to reduce vignetting, the front element still seems alarmingly unprotected. Fortunately, Sigma also included a slip-on circular adapter with a 72mm front thread, which allows attaching filters. Keep in mind though that the adapter will cause additional vignetting at wider apertures, so you might want to remove it during shooting.

The lens was designed for traditional 35mm systems (read full frame in digital world), so when used on APS-C type cameras with 1.6x crop factor, the field of view of the lens resembles that of a 22mm prime on a full frame body.

 

Summary
Lens Composition 14 elements in 10 groups
Angular Field ~114 degrees
Minimum Focus 18cm/7.1in
Focusing Action AF/MF, HSM
f-stop Scale f/2.8-f/22, manual
Filter Size Gelatin, rear-mounted
Lens Hood Built-in + metal, slip-on
Weight 655g/23.1oz
Dimensions 80x91mm/3.15x3.6"
Lens Case Vinyl (included)

 

Field Tests

If you never tried a 14mm lens before, the moment you mount Sigma 14mm f/2.8 EX DG ASPH HSM on a full frame camera, you will immediately be taken by its immense field of view. Because of such a wide field of view, the lens is not very suitable for everyday photography, unless you're taking pictures of expansive areas/landscapes or need to include as much coverage as possible in relatively small interiors (i.e. museums, art galleries etc.). But even then, composition with the lens would take some practice since you could literally include everything from the ground under your feet to distant clouds in the frame.

The AF system is pretty fast and silent, however, it is not extremely accurate at closer ranges and has a tendency to hunt, especially in low light conditions. For longer distances, this issue becomes less of a problem, since the depth of field of the lens would likely mask small focusing errors - you might even decide to manual focus the lens to speed up the operation and avoid unnecessary auto-refocusing.

Overall performance in the field was pretty decent. The lens produced pretty sharp images in the f/8-f/11 range on both APS-C as well as FF cameras, but seemed to struggle at wider apertures, with visibly softer borders.

 

Vignetting @ f/2.8 - full frame vs 1.6x crop (200mm)
Vignetting @ f/2.8 - full frame vs 1.6x crop (200mm)

 

The lens showed moderate level of vignetting on a full frame camera with wide open aperture. What is surprising is that the amount of vignetting here is not extreme as one might have expected from such a wide lens. As you stop down the lens, vignetting is reduced and by f/5.6 is all but gone. On an APS-C camera, with its smaller sensor, the lens naturally shows slightly better performance - vignetting is still present at f/2.8, but is pretty minimal by f/4.

Color reproduction was more or less accurate, however images carried rather low level of contrast at wider apertures. Images at f/2.8 seemed rather 'washed-out' with color levels constantly being skewed towards highlights. Stopping down the lens improved contrast and by f/5.6 or so, the lens produced pretty balanced images. Color fringing was visible predominantly around borders and at wider apertures, which is typical of majority of wide angle lenses. But on a positive side, axial CA (halation) was not visible throughout. Like most ultra wide angle lenses, Sigma 14mm f/2.8 EX DG ASPH HSM is quite prone to flare as well as to distortion, which was visible in on both APS-C as well as FF cameras.

 

ISO 100, 1/1250, f/2.8, 14mm (100% crop)
ISO 100, 1/1250, f/2.8, 14mm (100% crop)

 

Lab Tests

Please note that MTF50 results for APS-C and Full-Frame cameras are not cross-comparable despite the same normalized [0:1] range used to report results for both types of cameras.

 

Canon APS-C: Sigma 14mm f/2.8 EX DG ASPH HSM showed pretty good overall performance on an APS-C body. Center image resolution was decent with wide open aperture, improving quite nicely with stopped down aperture. In the f/4-f/11 range, center performance is quite respectable. Unfortunately, border quality was lagging center, especially at f/2.8, where quality quite mediocre. Fortunately, quality improved at f/4 and then improved further at f/5.6, reaching quite good levels. The lens performed best in the f/5.6-f/8 range, where it is capable of producing excellent 16in and decent 24in prints. Conclusion? Results are surprisingly good. While overall performance is not strictly speaking the best among fixed focal length lenses, the fact that the lens is so wide changes things. Here Sigma 14mm f/2.8 EX DG ASPH HSM earns both respect and envy since very few lenses with such a wide angle of view can produce comparable performance.

 

MTF50 (Line Width/Inch on the Print) @ 14mm
MTF50 (Line Width/Inch on the Print) @ 14mm

 

Normalized raw MTF50 @ 14mm
Normalized raw MTF50 @ 14mm

The lens showed decent handling of chromatic aberration. CA in the center was well under control, never exceeding ~0.5px throughout the tested aperture settings. CA around borders was higher - at f/2.8 it was reaching ~1.1px, dropping to ~0.6px by f/11.

 

Chromatic Aberration (APS-C) @ 14mm
Chromatic Aberration (APS-C) @ 14mm

Here are 100% crops taken with an APS-C type Canon Digital Rebel XTi comparing image borders at f/2.8 and f/8.

 

Image borders @ 14mm (100% crop): f/2.8 vs f/8
Image borders @ 14mm (100% crop): f/2.8 vs f/8

 

Canon FF: Regretfully, Sigma 14mm f/2.8 EX DG ASPH HSM did not hold its ground when used on a full frame camera. Center image quality remained pretty decent overall - at f/2.8 performance is already good and in the f/4-f/11 it's simply excellent. However, border image quality lags significantly and in the f/2.8-f/4 range it's plain average, if not mediocre. Performance gets better at f/5.6, but not by much and only by f/8 it gets to very good levels. Conclusion? Expectations not met and dreams of high performance ultra wide prime lens shattered. The lens does produce good performance in the f/8-f/11 range, but certainly under-delivers at wider apertures. Oh well...

 

Normalized raw MTF50 @ 14mm
Normalized raw MTF50 @ 14mm

We're dealing with a super wide angle lens here, so if you expected it not to produce any distortion, you are going to be sorely disappointed. The lens indeed exhibits barrel distortion and at 1.39% it is going to be visible in general photography. However, for such a wide angle, distortion can be considered well corrected.

 

Distortion (FF) @ 14mm
Distortion (FF) @ 14mm

Chromatic aberration on a full frame body was well under control in the center - here CA never exceeded ~0.5px throughout the tested aperture range. Border CA was somewhat higher, hovering around ~1.2px at f/2.8 and gradually dropping to a more manageable ~0.6px by f/11.

 

Chromatic Aberration (FF) @ 14mm
Chromatic Aberration (FF) @ 14mm

Here are 100% crops taken with a FF type Canon 5D comparing image borders at f/2.8 and f/8.

 

Image borders @ 14mm (100% crop): f/2.8 vs f/8
Image borders @ 14mm (100% crop): f/2.8 vs f/8

 

Alternatives

There are not that many alternative 14mm primes available on the market. Actually, with the exception of Voigtlander's Ultra Heliar ASPH 12mm f/5.6, Sigma's, Tamron's and Canon's 14mm primes are the widest rectilinear lenses available on the market. But considering that Voigtlander's Heliar can only be used on a Nikon's SLR with mirror lock-up, it and obviously Nikon's 14mm prime cannot even be considered alternatives for those of us using Canon or other SLRs. Ok, so as you've guessed it, Canon's EF 14mm f/2.8L II USM is one of the alternatives here. Tamron SP AF 14mm f/2.8 ASPH is another. That's pretty much it. If you want to expand your search, you will have to settle on a wider alternative. In this case, your choice can include Sigma's own 20mm f/1.8 EX DG HSM or Canon's EF 20mm f/2.8 USM.

 

Recommendation

It's rather hard to draw a verdict on Sigma 14mm f/2.8 EX DG ASPH HSM. The lens is a pretty mighty performer on an APS-C camera, with good image quality across the frame almost throughout the entire aperture range (almost, since at f/2.8 border performance is lagging somewhat). But, on an FF body the lens is a mixed performer, with very respectable center performance and pretty unimpressive border quality at wider aperture settings. So if you plan to use the lens on a FF camera like Canon 5D, prepare to stop down to at least f/8 to achieve best results across the frame. Other then that, you should be aware of the barrel distortion, which is not that unusual for wide angle lenses in general, as well as vignetting and some CA around borders. But then again, this is one of the widest rectilinear lenses ever made and as you know, the wider the lens, the harder to make it perform well. As I said, hard to make a conclusive recommendation...