Introduction

Canon EF 28mm f/1.8 USM is one of the two (the other one being EF 28mm f/2.8) 28mm lenses in Canon's modern lineup. The lens was introduced back in 1995, and currently remains the fastest consumer oriented (read non L) wide angle offered by the company. Priced at about US$400 (as of February 2008), it remains within reach of amateurs and professionals alike. The lens carries an EF designation, meaning it was designed for full frame cameras, so on an APS-C body with 1.6x crop sensor its field of view will be similar to that of a 44mm lens, thus loosing its wide angle appeal.

The optical construction of the lens consists of 10 elements in 9 groups with a single aspherical element. Build quality of the lens is pretty decent, similar to that of Canon's other consumer grade lenses - outer barrel is made of hardened plastic and focus ring is fully rubberized and smooth. There is no wobbling inside or out, so the lens does not feel as flimsy as some other consumer grade lenses. The lens offers ring-type USM AF as well as a full-time manual focusing systems (controlled by an AF/MF switch on the side of the barrel). Like all modern Canon lenses, EF 28mm f/1.8 USM has a fully electronic aperture control, meaning that there's no dedicated aperture ring and settings are controlled through your camera.

Despite its relatively large maximum aperture, Canon EF 28mm f/1.8 USM is quite a light and compact lens, weighing mere 310g (10.9oz) and measuring 73 x 55mm (2.9 x 2.2in). The lens implements internal focusing mechanism, so the overall length of the lens remains constant throughout focusing. The minimum focusing distance is 25cm (0.8ft) and the minimum aperture is f/22. The filter thread is 58mm and since the front element does not rotate, the lens would allow using circular polarizers.

 

Image

 

The factory box includes Canon EF 28mm f/1.8 USM lens, front and rear lens caps, manual and registration card. The lens accepts Canon's Gelatin Filter Holder Adapter III and IV and is compatible with extension tubes EF 12 II and EF 25 II. Lens hood EW-63II and soft lens case LP814 are sold separately.

 

Summary
Lens Composition 10 elements in 9 groups
Angular Field 75 degrees
Minimum Focus 25cm/0.8ft
Focusing Action AF/MF, USM
f-stop Scale f/1.8-f/22, camera-controlled
Filter Size 58mm
Lens Hood EW-63II (optional)
Weight 310g/10.9oz
Dimensions 73x55mm/2.9x2.2"
Lens Case LP814 (optional)

 

Field Tests

Canon EF 28mm f/1.8 USM did not really impress in the field - image quality seemed to be rather on the softer side around borders. This was the case on both APS-C as well as FF cameras, but the lens particularly struggled on a FF body, where border quality remained soft almost throughout the entire tested aperture range.

The lens handling was not any different than any other AF lens in this class. While the lens is not the smallest 28mm prime ever made, it's compact enough to benefit those using smaller APS-C type bodies like Digital Rebel XTi, where the lens would produce a focal length equivalent to a standard prime. The AF system was somewhat of a mixed bag - it was quite fast and silent, but tended to re-focus a few times before locking on a target. Hunting was common in both low light as well as normal lightning conditions. The focusing ring is detached from the AF operation (the ring does not rotate during auto-focusing), so you can use it to fine tune the focusing after the AF locks on the target. As mentioned earlier, the lens supports manual focusing, but the lens is not really designed with manual focusing in mind - the focusing ring moves from the closeup to the infinity in about 90 degrees, making precise manual focusing rather hard.

 

ISO 400, 1/160, f/1.8, 28mm (Canon 5D)
ISO 400, 1/160, f/1.8, 28mm (Canon 5D)

 

When shot with wide open aperture, the lens produced out-of-focus highlights that were mostly uniformly lit but often carried harshly defined edges. The effect is not too distracting, but not pleasant either. Contrast transitions in the background and foreground OOF areas were somewhere in the middle - not too harsh, but not too smooth either. There was no sign of double-edging around back/fore-ground objects.

 

Vignetting @ f/1.8 - full frame vs 1.6x crop (135mm)
Vignetting @ f/1.8 - full frame vs 1.6x crop (135mm)

 

Canon EF 28mm f/1.8 USM showcased noticeable vignetting at f/1.8 when used on a full frame camera. Vignetting continued to persist at f/2.8, slowly disappearing by f/4-f/5.6. On an APS-C body, the lens produced practically no visible vignetting throughout the tested aperture range.

The lens produced noticeable color fringing that was visible pretty much throughout the aperture range on both APS-C as well as FF cameras (check the image crop below as well as purple highlights in the urban area shot in the image gallery). Axial CA (halation) was pretty insignificant at f/1.8, disappearing by f/2.8 (notice white halos around flowers in the blooming tree shot in the image gallery). Generally speaking, the lens did not handle color well - images at wider apertures were washed out, lacking good contrast separation across the entire frame. The lens also fell prone to flare at wide apertures, and showed noticeable degree of distortion.

 

ISO 100, 1/4000, f/2.8, 135mm (100% crop)
ISO 100, 1/4000, f/2.8, 135mm (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: Canon EF 28mm f/1.8 USM showcased somewhat of a mixed performance on an APS-C camera. Center performance was quite decent in general - at f/1.8 image quality in the center is average, but more or less acceptable, and from f/2.8 on, quality is quite good. Regretfully, border image quality is quite unimpressive, especially at wider apertures - from f/1.8 through f/2.8 quality around borders is mediocre at best. Even at f/4 quality is just average. You need to actually stop down to f/8 to achieve good quality across the frame. Here the lens would produce good quality 16in and decent 19in prints, which is not that impressive for a 28mm prime. Conclusion? While center performance is pretty decent, border quality is practically disastrous - when stacked against other 28mm prime lenses, Canon EF 28mm f/1.8 USM would fall somewhere in the bottom of the stack.

 

MTF50 (Line Width/Inch on the Print) @ 28mm
MTF50 (Line Width/Inch on the Print) @ 28mm

 

Normalized raw MTF50 @ 28mm
Normalized raw MTF50 @ 28mm

 

Chromatic aberration on an APS-C body was pretty low in the center and low to moderate around borders. Center CA averaged ~0.5px across the aperture range, while CA around borders hovered at ~1px with wider apertures, growing to ~1.1px by f/11.

 

Chromatic Aberration (APS-C) @ 28mm
Chromatic Aberration (APS-C) @ 28mm

 

Here are 100% crops taken with an APS-C type Canon Digital Rebel XTi comparing image borders at f/1.8 and f/8.

 

Image borders @ 28mm (100% crop): f/1.8 vs f/8
Image borders @ 28mm (100% crop): f/1.8 vs f/8

 

Canon FF: The lens did not produce any miracles on a full frame body - overall performance actually degraded slightly. Center image quality continued to remain consistently good throughout the aperture settings, but border quality fell apart. From f/1.8 through f/4 border performance is simply inadequate. Even at f/5.6, quality is just average and you need to stop down to f/8-f/11 to achieve more or less decent results. But even then, the gap in performance between the image center and borders is pretty large. Conclusion? This is pretty bad. It is expected that most fast wide angle lenses will show some weakness at wider apertures, but Canon EF 28mm f/1.8 shows pretty weak border performance even at smaller apertures, where most lenses are already capable of quite decent performance.

 

Normalized raw MTF50 @ 28mm
Normalized raw MTF50 @ 28mm

 

Canon EF 28mm f/1.8 USM showed pronounced degree of barrel distortion. At 1.36%, distortion will be visible in general photography and can cause some problems when shooting architecture and other types of scenery with straight lines around corners.

 

Distortion (FF) @ 35mm
Distortion (FF) @ 35mm

 

Chromatic aberration handling on a full frame camera remained pretty constant - CA in the center was quite low, averaging ~0.4px across the tested aperture settings, while CA around borders hovered at ~1px throughout the aperture range. Not the worst case one can see in a wide angle.

 

Chromatic Aberration (FF) @ 28mm
Chromatic Aberration (FF) @ 28mm

 

Here are 100% crops taken with a FF type Canon 5D comparing image borders at f/1.8 and f/8.

 

Image borders @ 28mm (100% crop): f/1.8 vs f/8
Image borders @ 28mm (100% crop): f/1.8 vs f/8

 

Alternatives

As mentioned above, Canon currently offers another 28mm prime lens - EF 28mm f/2.8, which might appeal to you if you're on a budget, but performance-wise it falls short of the expectations. If you're willing to spend a bit more, then you might want to consider EF 35mm f/1.4L USM which offers pretty good overall characteristics. Canon also offers another fast wide angle - EF 24mm f/1.4L USM, but unlike its 35mm brethren, this lens does show some weakness around borders at wider aperture settings. Outside of the Canon camp, Sigma offers a wide selection of wide angle primes, including Sigma 20mm f/1.8 EX DG, 24mm f/1.8 EX DG and 28mm f/1.8 EX DG. While all three lenses offer pretty large maximum aperture levels, all three suffer at wide apertures and are really usable once stopped down to f/2.8 or beyond.

 

Recommendation

Canon EF 28mm f/1.8 USM held a lot of promise on paper - a well performing fast wide angle prime, with silent and accurate AF system in a compact and light format that is affordable to a mainstream photographer. Unfortunately, in the real life the lens does not come even close to all these promises. THe biggest grunt here is about its performance around borders - after all, what is the point of buying a fast prime if you cannot use it effectively until stopped down to f/8 or so? Even then, numerous artifacts such as color fringing around borders, noticeable distortion and mediocre handling of color, will ultimately spoil the entire experience. So where does the lens shine? Nowhere... The lens does not really offer any strengths that are worth mentioning and while you can probably still use it if you're prepared to stop down to achieve more or less acceptable results, one might ask - 'Why bother?' Indeed, why when there is a plethora of other lenses out there...