Introduction

Canon EF 75-300mm f/4.5-5.6 DO IS USM is one of a about half a dozen telephoto zoom lenses that the company offers in its modern lineup. First introduced in March of 2004 at a retail price of ~US$1,300, the lens now sells for a little bit over US$1,000 (as of May 2008). While not terribly expensive, the lens is probably not going to be a first choice for the mainstream consumer - not just because of the price, but rather because of a pretty tough in-house competition from lenses like EF 75-300mm f/4.-5.6 IS USM, EF 70-200mm f/4L IS USM and a few others.

The optical construction of the lens consists of 18 elements in 12 groups, however, unlike majority of the conventional lenses implementing refractive lens elements, Canon EF 70-300mm f/4.5-5.6 DO IS USM incorporates a multi-layered diffractive optical elements, which are significantly more compact in size and provide improved handling of various forms of color aberration (or so the theory goes). Dimension-wise, the lens is actually pretty compact, albeit a little bit bulky, when fully collapsed - it measures 82 x 100mm (3.2 x 3.9in). However, the lens extends during zooming, practically doubling in length. The build quality of the lens is pretty decent - it is not as cheap and cheesy looking as many of Canon's consumer grade lenses, but it's not on par with L type pro-grade zooms like EF 70-200mm series. The all-plastic barrel and inner cams obviously keep the weight of the lens down, but at 720g (25.4oz), it is not particularly light to begin with. The inner cams wobble a little bit and don't really improve the feel.

 

Image

 

As you might have guessed from its name, Canon EF 75-300mm f/4.5-5.6 DO IS USM incorporates an image stabilization technology. This is a second generation IS that provides two modes of operation: mode 1 for horizontal and vertical shake correction, which is typically suitable for regular handheld photography, and mode 2 for only vertical shake correction, which is suitable for panning (action based photography). According to Canon, the IS system correction provides gain for up to 3 f-stops.

Like all modern EF type lenses, Canon EF 75-300mm f/4.5-5.6 DO IS USM is an auto-focus lens, although in addition to the typical AF operations, the lens supports fully manual focusing with a dedicated focusing ring - although you first need to switch the lens to manual focus mode using the dedicated AF/MF switch located on the side of the barrel. Unfortunately, the lens does not have a dedicated aperture ring, so the aperture levels are set directly from the camera. The minimum supported aperture is f/38 and the minimum focusing distance is 1.4m (4.6ft). The lens accepts 58mm screw-in type filters.

The factory box include Canon EF 70-300mm f/4.5-5.6 DO IS USM lens, front and rear caps, LP1116 soft lens case, ET-65B lens hood, manual and registration card. Since the lens was designed for full frame cameras, when used on APS-C type bodies with 1.6x crop factors, the field of view of the lens resemble that of a 112-480mm zoom on a full frame camera.

 

Summary
Lens Composition 18 elements in 12 groups
Angular Field 34 - 8 degrees
Minimum Focus 1.4m/4.6ft
Focusing Action AF/MF, USM
f-stop Scale f/4.5-f/38, camera-controlled
Filter Size 58mm
Lens Hood ET-65B (included)
Weight 720g/25.4oz
Dimensions 82.4x99.9mm/3.2x3.9"
Lens Case LP1116 (included)

 

Field Tests

One of the much touted advantages of EF 70-300mm f/4.5-5.6 DO IS USM mentioned in Canon's marketing literature is the significantly smaller size of the lens, which was possible to achieve due to the innovating design involving diffractive optics. After spending a week shooting with the lens, I'm not so sure that the extra 5-7cm of length (when compared to say Canon EF 70-300mm f/4-5.6 IS USM) is that much of an advantage. The lens is shorter but bulkier and leaves an impression of being heavier (partially to its bulky feel). The weight of the lens is actually substantial enough to cause the inner cams to collapse/extend under their own weight when the lens is pointed up/down. This actually makes shooting at close to vertical angles pretty problematic - at 70mm you can lock the lens cams using a dedicated switch, but at any other focal length you will have to hold the zoom ring with one hand to prevent the cams from extending. Not very convenient.

Aside from this rather annoying quirk, the lens handles like any other Canon zoom. The AF system is pretty accurate, although it felt a little bit slower when compared to some of the more recently released tele zooms like EF 70-200mm f/4L IS USM. As mentioned above, the lens supports manual focusing, so you can always rely on your eyesight to improve the accuracy when AF fails - that actually happened quite often with EF 70-300mm f/4.5-5.6 DO ID USM is low light situations. In general, auto-focus systems pretty much seem to give up in low light conditions., and EF 70-300mm f/4.5-5.6 DO IS USM is no exception here. If you do decide to manual focus the lens, keep the mind that the focusing ring rotates about 100 degrees from the closeup all the way to the infinity - not necessarily the most precise system, but not that bad either.

Image quality-wise, Canon EF 70-300mm f/4.5-5.6 DO IS USM showcased somewhat mixed performance, with slightly better overall performance on a crop sensor camera. The lens produced pretty good results in the shorter end of the zoom range. Overall quality seemed to peak around f/8-f/11, where both borders and center areas were uniformly sharp. From 70mm to 135mm image quality in the center was consistently good, while border quality suffered a little bit at wider apertures. From 135mm to 200mm the lens seemed to start loose its sharpness around borders, however, image quality across the entire frame started to really suffer the moment the lens is zoomed past 200mm. Quality degradation in the 200-300mm range was visible across the aperture range but f/5.6 suffered most.

 

Vignetting @ f/4.5 - full frame vs 1.6x crop (70mm)
Vignetting @ f/4.5 - full frame vs 1.6x crop (70mm)

 

Vignetting @ f/5.6 - full frame vs 1.6x crop (300mm)
Vignetting @ f/5.6 - full frame vs 1.6x crop (300mm)

 

The lens showed somewhat surprising behavior when it came down to vignetting. At 70mm, the lens shows good handling of light falloff on both FF as well as APS-C cameras - the amount of vignetting even with wide open aperture is pretty minimal and once stopped down to f/5.6 is practically non-existent. However, once the lens is zoomed towards the longer end of the focal range, the amount of vignetting starts to increase and at 300mm the lens clearly vignettes more then at 70mm. Of course, more is a relative term here - even at 300mm vignetting is still not as bad as with some ultra fast, ultra wide angle lenses.

Canon EF 70-300mm f/4.5-5.6 DO IS USM also fell prone to surprisingly large amount of flare and aperture ghosting, both of which can be observed in the image below. Vailing and reflective flare persisted with bright light sources directly within or close to the frame as well as in moderately bright backlit environments. Particularly harsh lightning conditions also caused severe aperture ghosting across the entire zoom range as well as across all aperture settings.

 

ISO 400, 1/320, f/8, 70mm (Canon 5D)
ISO 400, 1/320, f/8, 70mm (Canon 5D)

 

Color reproduction was a little bit off, with colors generally being warmer across the entire zoom range and all apertures. The images lacked contrast at wider apertures, leaving impression of being washed out a little bit, even lifeless. Stopping down improved contrast levels a little bit, but the lens did not manage to deliver the 'punch' no matter what. Regretfully, the lens fell prone to some color fringing, which seemed to spring up predominantly around borders across the zoom range. The lens also produced minor levels of axial CA (halation) across the aperture and zoom ranges, which were often noticeable in high contrast areas.

 

ISO 100, 1/800, f/4.5, 70mm
ISO 100, 1/800, f/4.5, 70mm

 


 

Lab Tests

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

 

Canon APS-C: Canon EF 70-300mm f/4.5-5.6 DO IS USM showed somewhat inconsistent performance on an APS-C body. Center image quality was excellent throughout the aperture ranges, although quality degraded towards the 300mm focal length. On the other hand, border image quality varied drastically, from mediocre at wider apertures in the 70-200mm and pretty much throughout the aperture range at 300mm to pretty good in the f/8-f/11 range in the 70-200mm range. The lens clearly shows better performance in the shorter, 70-200mm, zoom range, where it can produce excellent 16in and decent 19in prints in the f/8-f/11 range, while  at 300mm you'll get good 11in and OK 16in prints. Conclusion? The results are not very inspiring, but not that bad either, especially in towards the shorter end of the zoom range.

 

MTF50 (Line Width/Inch on the Print) @ 70mm
MTF50 (Line Width/Inch on the Print) @ 70mm

 

Normalized raw MTF50 @ 70mm
Normalized raw MTF50 @ 70mm

 

MTF50 (Line Width/Inch on the Print) @ 100mm
MTF50 (Line Width/Inch on the Print) @ 100mm

 

Normalized raw MTF50 @ 100mm
Normalized raw MTF50 @ 100mm

 

MTF50 (Line Width/Inch on the Print) @ 200mm
MTF50 (Line Width/Inch on the Print) @ 200mm

 

Normalized raw MTF50 @ 200mm
Normalized raw MTF50 @ 200mm

 

MTF50 (Line Width/Inch on the Print) @ 300mm
MTF50 (Line Width/Inch on the Print) @ 300mm

 

Normalized raw MTF50 @ 300mm
Normalized raw MTF50 @ 300mm

 

Chromatic aberration on an APS-C body was pretty minimal, with center CA hovering at ~0.5px throughout the zoom range and tested apertures, while border CA remained at ~0.7px throughout the most of zoom/aperture settings.

 

Chromatic Aberration (APS-C) - Center
Chromatic Aberration (APS-C) - Center

 

Chromatic Aberration (APS-C) - Borders
Chromatic Aberration (APS-C) - Borders

 

Here are 100% crops taken with an APS-C type Canon Digital Rebel XTi, comparing image borders at 70mm, 100mm, 200mm and 300mm.

 

Image borders @ 70mm (100% crop): f/4.5 vs f/8
Image borders @ 70mm (100% crop): f/4.5 vs f/8

 

Image borders @ 100mm (100% crop): f/5.0 vs f/8
Image borders @ 100mm (100% crop): f/5.0 vs f/8

 

Image borders @ 200mm (100% crop): f/5.0 vs f/8
Image borders @ 200mm (100% crop): f/5.0 vs f/8

 

Image borders @ 300mm (100% crop): f/5.5 vs f/8
Image borders @ 300mm (100% crop): f/5.5 vs f/8

 

Canon FF: The lens produced marginally worse results on a full frame body. Center image performance remained quite good throughout the tested aperture ranges and across the zoom range, although like with an APS-C body, quality in the center degraded towards 300mm. Border quality remained quite mediocre at wider apertures throughout the zoom range, and the lens only managed to produce decent border image quality in the f/8-f/11 range, but even then quite inconsistently. 300mm still remains the weakest point for the lens and here image quality around borders is rather uninspiring in general. Conclusion? The overall performance is probably on par with many consumer zooms available on the market, but for a moderately expensive zoom with such a fancy optical design, the lens disappoints.

 

Normalized raw MTF50 @ 70mm
Normalized raw MTF50 @ 70mm

 

Normalized raw MTF50 @ 100mm
Normalized raw MTF50 @ 100mm

 

Normalized raw MTF50 @ 200mm
Normalized raw MTF50 @ 200mm

 

Normalized raw MTF50 @ 300mm
Normalized raw MTF50 @ 300mm

 

Canon EF 70-300mm f/4.5-5.6 DO IS USM showed varying degree of distortion throughout the zoom range. At 70mm and 100mm the lens shows pretty minimal barrel distortion of 0.53% and 0.64% (respectively), which should not be a major problem in general photography. Surprisingly, amount of distortion actually increases towards the longer end of the zoom range and at 200mm and 300mm the lens shows more pronounced barrel distortion of 1.02% and 1.15% (respectively), which are high enough to be visible in certain type of photography (i.e. architectural shots or images).

 

Distortion (FF) @ 70mm, 100mm (top), 200mm, 300mm (bottom)
Distortion (FF) @ 70mm, 100mm (top), 200mm, 300mm (bottom)

 

Chromatic aberration was under control on a FF camera. Center CA did not exceed ~0.5px throughout the zoom range and across all tested apertures, while border CA hovered at ~0.7px throughout.

 

Chromatic Aberration (FF) - Center
Chromatic Aberration (FF) - Center

 

Chromatic Aberration (FF) - Borders
Chromatic Aberration (FF) - Borders

 

Here are 100% crops taken with a FF type Canon 5D, comparing image borders at 70mm, 100mm, 200mm and 300mm.

 

Image borders @ 70mm (100% crop): f/4.5 vs f/8
Image borders @ 70mm (100% crop): f/4.5 vs f/8

 

Image borders @ 100mm (100% crop): f/5.0 vs f/8
Image borders @ 100mm (100% crop): f/5.0 vs f/8

 

Image borders @ 200mm (100% crop): f/5.0 vs f/8
Image borders @ 200mm (100% crop): f/5.0 vs f/8

 

Image borders @ 300mm (100% crop): f/5.5 vs f/8
Image borders @ 300mm (100% crop): f/5.5 vs f/8

 

Alternatives

When it comes down to telephoto zooms, Canon alone offers more then a dozen of lenses of pretty much all shapes, colors and flavors. If you add all the third party zoom lenses from manufacturers like Tokina, Sigma and Tamron, you will easily end up with a list of at least three dozen lenses. You can try narrowing down this list by identifying whether or not you really need 300mm focal range. If so, then the first lens on your list should be a cheaper, non DO version of 70-300mm, Canon EF 70-300mm f/4-5.6 IS USM, which offers image quality as good and in some aspects even better then the more expensive DO version. Alternatively, you might also want to take a look at Sigma's APO 120-300mm f/2.8 EX DG HSM or APO 100-300mm f/4 EX DG HSM zooms, both of which offer a pretty good price/performance trade-off. However, if you don't really need that extra reach, then you might want to start your search with Canon's four 70-200mm zooms - Canon EF 70-200mm f/2.8L IS USM, Canon EF 70-200mm f/2.8L USM, Canon EF 70-200mm f/4L IS USM and Canon EF 70-200mm f/4L USM. Keep in mind though, that while all four lenses have exactly same focal zoom range, their optical designs differ and so does their performance. Outside of Canon's camp, you might also want to consider Sigma's APO 70-200mm f/2.8 EX DG MACRO HSM or its newer revision APO 70-200mm f/2.8 II EX DG MACRO HSM.

 

Recommendation

Canon EF 70-300mm f/4.5-5.6 DO IS USM is a pretty unique lens in sense that it is one of the only two Canon lenses that incorporate diffractive optics. When the lens was first released in 2004 (following the release of Canon EF 400mm f/4 DO IS USM), Canon was believed to quickly follow up with additional lens models that would include DO elements. Yet four years later there are no new additions from Canon. After testing the lens, it kind of becomes clear why - Canon EF 70-300mm f/4.5-5.6 DO IS USM does not simply provide a good bang for the buck. The lens delivers semi-decent performance, but costs ~2x more then its closest in-house rival EF 70-300mm f/4.-5.6 ID USM. Considering that the image sharpness, level of artifacts and build quality of the lens are not necessarily the best in its class, would anyone be willing to shed extra ~US$500 for a slightly more compact form factor? I would not... And neither should you - at least not until you take a look at some of the alternatives mentioned above and compare their performance to Canon EF 70-300mm f/4.5-5.6 DO IS USM.