Introduction

Canon EF 300mm f/4L IS USM, which replaced a similar model without Image Stabilization technology, is one of about half a dozen telephoto lenses in Canon's current lens lineup. Priced at about US$1,150 (as of July 2007), the lens is probably not going to be the first choice for a beginner photographer, but is nevertheless one of the most affordable long telephoto lenses on the market. The lens is designed for EF mount and on APS-C cameras with 1.6x crop factor it will have a field of view similar to that of a 480mm lens on a full-frame body.

The optical construction of the lens consists of 15 elements in 11 groups, including two UD (ultra low dispersion) glass elements. Build quality is superb, as expected from an L lens - lens barrel is made of lightweight metal, as is built-in extendable lens hood. The focus ring is fully rubberized and very smooth. As mentioned earlier, Canon included second generation Image Stabilization technology with the lens, with two modes of operation.

Canon 300mm f/4L IS USM is certainly no lightweight in the world of telephoto lenses (IS is obviously partially responsible here), weighing 1190g (2.6lb) and measuring 90x221mm (3.5x8.7in). The lens offers ring-type USM AF as well as full-time manual focusing, which can be controlled by a switch on the side of the barrel. The minimum focusing distance is 1.5m (4.9ft), while the minimum aperture is f/32 (aperture is camera controlled, so there's no dedicating aperture ring). The filter size if 77mm. To help improve AF speed, Canon included a focusing distance limiter which allows for two modes: 1.5m to infinity and 3m to infinity.

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The lens is compatible with Canon's 1.4x II and 2x II Extenders as well as EF 12 II and EF 25 II Extension Tubes. You can also attach a gelatin filter to the lens using a Gelatin Filter Holder Adapter III or IV. The factory box includes Canon EF 300mm f/4L IS USM lens, front and rear caps, a tripod mount ring,  LZ1128 lens case, manual and registration card.

 

Summary
Lens Composition 15 elements in 11 groups
Angular Field 8 degrees
Minimum Focus 1.5m/4.9ft
Focusing Action AF/MF, USM-type
f-stop Scale f/4-f/32, camera-controlled
Filter Size 77mm
Lens Hood Built-in
Weight 1190g/2.6lbs
Dimensions 90x221mm/3.5x8.7"
Lens Case LZ1128 (included)

 

Field Tests

The lens showed pretty good performance in the field. Images were sharp and contrasty across the tested aperture range (with colors coming up on a slightly warmer side, which is pretty typical for Canon lenses). There was no visual degradation in border quality across the aperture range. I have not had a chance to test the lens with either of Canon's tele-converters, so it would be interesting to see whether the border performance remains adequate.

The lens handled with ease - while not the lightest telephoto on the market, you can still shoot it from hand, and IS is here to help. As I've been saying in my other reviews, I like the idea of having an image stabilization available for long-range photography, but I am not that convinced that having IS built into a lens is a better option then having it in a camera. Canon could have reduced the size (and probably weight) of the lens had it not been for the IS. Just random rumbling...

Anyhow, AF system was quite fast on this lens, but did hunt occasionally at close distances (closeup photography). But since I used the lens primarily for telephoto shooting, this did not really bother me at all. For those of you who plan to use the lens for closeup photography, you can always switch the lens into MF mode.

 

Vignetting @ f/4 - full frame vs 1.6x crop
Vignetting @ f/4 - full frame vs 1.6x crop

 

Vignetting was well under control on both APS-C and FF cameras, which does not come as a surprise for such a long telephoto lens. Ditto for barrel distortion and flare. Color fringing was very rare (it would creep up occasionally around corners in some very challenging lightning situations), but even then was mild at worst.

 

ISO 100, 1/400, f/4, 300mm (100% crop)
ISO 100, 1/400, f/4, 300mm (100% crop)

 

Sample images coming soon...

 

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: The lens performed quite well in the lab, with balanced results across tested aperture range. While both center and border performance was not necessarily the highest among all fixed focal lenses, it was quite respectable. More importantly, there were no major fall-offs across the aperture range, with border sharpness closely matching performance in the center. At its peak the lens is capable of producing outstanding 16in and decent 24in prints, which falls within the range expected from a good quality prime telephoto lens. Conclusion? With no weak points and no fall-offs around borders, there's a lot to like about Canon EF 300mm f/4L IS USM. The question is - how is it going to handle on a full-frame body?

 

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 was well under control with an APS-C camera, not exceeding ~0.4px in the center and ~0.6px throughout the tested aperture range. This is not a surprise for a prime telephoto lens.

 

Image borders @ 300mm (100% crop): f/4 vs f/8
Image borders @ 300mm (100% crop): f/4 vs f/8

Canon FF: The lens continued to show solid performance on a full frame Canon 5D, with overall performance trend closely matching that of an APS-C camera. Both center and border performance, while not unique, remained consistent throughout the aperture range, which is always a welcoming sign. Conclusion? I'm just gonna repeat myself here - solid performance in an attractive overall package.

 

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

 

CA on a full-frame Canon 5D was quite moderate as well. CA averaged ~0.3px in the center and ~0.8px around borders throughout the aperture range.

 

Image borders @ 300mm (100% crop): f/4 vs f/8
Image borders @ 300mm (100% crop): f/4 vs f/8

 

Alternatives

As mentioned earlier in the review, Canon currently offers over half a dozen long (super) telephoto lenses. However, while there is plenty to choose from, Canon EF 300mm f/4L IS USM remains one of the most affordable lens in this lineup, with most other lenses costing 2x/3x times. Nevertheless, if you're still interested, take a look at EF 300mm f/2.8L IS USM, which is a faster variant of the lens reviewed here. For a longer focal length, take a look at the trio of 400mm lenses - EF 400mm f/2.8L IS USM, EF 400mm f/4 DO IS USM and EF 400mm f/5.6L USM. Outside of the Canon camp, Sigma offers APO 300mm f/2.8 EX DG HSM and Tamron offers SP AF 300mm f/2.8 LD.

 

Recommendation

Considering the overall performance, build quality, features and reasonable pricing (reasonable is a relative term here), Canon EF 300mm f/4L IS USM measures up quite nicely against other long telephoto lenses available on the market. While users of full-frame cameras might look at longer alternatives for their sports and wildlife photography needs, for those of us using APS-C cameras with 1.6x crop this lens should become THE default telephoto lens of choice. Unless of course you're willing to go with a slightly slower but longer lens (yes, I'm talking about Canon's EF 400mm f/5.6L USM).