Canon EF 24mm f/1.4L II USM

(From Canon lens literature) Canon's newest fixed length L-series lens, the EF 24mm ƒ/1.4L II USM, incorporates the newest in Canon lens technology for spectacular sharpness and impressive performance at all settings.

SLRgear Review
January 12, 2009
by Andrew Alexander

The Canon EF 24mm ƒ/1.4L II USM was introduced in the lead-up to Photokina 2008, as an update to its pre-existing 24mm ƒ/1.4. Introduced in December 1997, the previous version of the 24mm ƒ/1.4 was probably getting a little bit long in the tooth, despite having all the fixtures and trimmings of an L-class USM lens.

The upgrade to the lens is fairly substantial; it features 8 diaphragm blades in the aperture instead of 7, and the blades are now rounded. The lens elements have been regrouped, and an additional group is now present. Two ultra-low dispersion (UD) glass elements are used instead of just one. Finally, the new version of this lens is slightly heavier (100 grams) and a bit longer and wider.

The EF lens is compatible with both full-frame and cropped-frame Canon SLR cameras, though on the latter the lens will have an effective field of view of approximately 38mm, negating some of the wide-angle appeal. However, for wide-angle glass in the Canon category, there's none faster. The lens ships with a petal-shaped lens hood and pouch, and is expected to retail for approximately $1,700.

Sharpness
The Canon 24mm ƒ/1.4L II is a very sharp lens, especially considering the wide angle of its focal length and the maximum aperture setting of ƒ/1.4. Sharpness wide open at ƒ/1.4 is the weak point for this lens. On the reduced-frame 20D, the crop factor focuses on the 'sweet spot' of the lens, producing a relatively sharp (1.5 BxU center, 3 BxU corners) image; on the full-frame 5D, corner softness is an issue, with the centers being relatively sharp at 1.5 BxU, but the corners showing up to 6 BxU of softness. It could be argued that these results are just the result of the effects of shooting a flat chart with a wide-angle lens, except that as the lens is stopped down, corner-to-corner sharpness becomes excellent. By ƒ/2.8, the lens produces practically tack-sharp images, improving marginally as the lens is stopped down through to ƒ/8.

Diffraction limiting seems to set in around ƒ/8, though the effects aren't really noticeable until ƒ/16, where the lens produces 2 BxU on both sub-frame and full-frame cameras. Performance fully stopped down at ƒ/22 is still excellent, at around 3 BxU across the frame.

One noteworthy aberration exists with the lens set to ƒ/2 on the full-frame 5D; central sharpness increases remarkably in comparison to ƒ/1.4, but corner softness also increases by 1-2 BxU. Stopping down to ƒ/2.8 reduces corner softness dramatically, and by ƒ/4 it's no longer a factor.

In summary, expect some measure of corner softness when using the lens at wide apertures on a full-frame camera body, but otherwise sharpness will be excellent with this lens.

Chromatic Aberration
The 24mm ƒ/1.4L II is well-treated to resist chromatic aberration. Our lab testing shows only slight evidence of CA in the corners when used at wider apertures, but in practical application (and looking at the sample images) we're challenged to find any at all.

Shading (''Vignetting'')
On the reduced-frame 20D, the 24mm ƒ/1.4L II USM shows some signs of light falloff in the corners, when used at ƒ/1.4 (2/3EV) and ƒ/2 (1/3EV). By ƒ/2.8, corner shading dips below 1/4 EV, a negligible difference.

It's a completely different story with the lens mounted on the full-frame 5D. The lens produces extremely dark corners when used with large apertures; at ƒ/1.4, the corners of the image are almost two stops darker than the center! This reduces to one stop by ƒ/2.8, and by ƒ/5.6 the differential hovers at 2/3 of a stop all the way through to ƒ/22. For this reason, users of this lens will want to become familiar with vignetting correction in post-processing software, or invest in a center-weighted ND filter (if such exists in the 77mm mount).

Distortion
Distortion is well-controlled in this lens. On the subframe 20D, the lens produces slight barrel distortion: 0.25% in the corners, to be exact. It's just slightly more prominent on the full-frame 5D, at 0.3% in the corners, but in both of these cases this is excellent performance for such a wide-angle lens.

Autofocus Operation
Autofocus operation was very quick, well under a second to rack through the entire focus range. As a USM lens, focus action is conducted very quietly. The focus ring doesn't turn while autofocusing, and the user can override autofocus and focus manually at any point by turning the focus ring.

Macro
With a magnification ratio of 1:5.9 (0.17x), the 24mm ƒ/1.4L II is not a great choice for macro work. Its minimum close-focus distance is just under 10 inches (25cm), and the manual does indicate the lens is compatible with the EF12 II extension tube and 500C close-up filter.

Build Quality and Handling
The 24mm ƒ/1.4L II USM is built to very high standards, a good example of the price differential demanded by L-class lenses. The lens is solidly built, with weather and dust seals, a fine matte-black finish and a metal lens mount. The lens sports a 77mm plastic filter thread. The front lens element will not rotate during focus operations.

The lens is fairly front-heavy, with the larger lens elements being placed there; the overall package is quite heavy. The lens is adorned with a windowed distance scale in imperial and metric measurements, as well as a depth-of-field scale (complete with infrared index point). The only other feature apart from the focus ring is a switch which allows the user to disable autofocus operation on the lens.

The focus ring is mounted near the front of the lens with a nice rubber ribbed pattern that is well-dampened and easy to grip, and 3/4 of an inch wide. Manual focus operation is smooth and easy, taking approximately 120 degrees to go from closest focus to infinity. Both points of the spectrum end in hard stops, and it is possible to focus past infinity.

The EW-83K lens hood is a bayonet-mount, petal-shaped hood that adds two inches to the overall length of the lens when mounted. The hood reverses onto the lens for easy storage.

Alternatives

Canon EF 24mm ƒ/1.4L USM ~$1,100
The first obvious alternative would be the predecessor version of the lens, which should be available at considerable savings now that a newer version has hit the market. We haven't tested this version of the lens, so we can't tell you which is the better lens.

Canon EF 24mm ƒ/2.8 ~$300
If you didn't need the wide aperture (or didn't want the weight or expense of the ƒ/1.4 version), the ƒ/2.8 version of the 24mm prime is an option. However, our tests show that the ƒ/1.4 is head-and-shoulders above the ƒ/2.8 version, in all regards. In this case, you really do get what you pay for.

Sigma 24mm ƒ/1.8 EX DG Aspherical Macro ~$300
We haven't yet tested the Sigma 24mm, but there is definite opportunity for cost savings here. As well, the Sigma 24mm offers substantial macro performance.

Conclusion
The Canon 24mm ƒ/1.4L II USM is an excellent lens, with only two reservations, both relating to the lens' usage on full-frame bodies. The first is some corner softness when used at wide apertures; the second is substantial corner shading, upwards of two stops when used wide open. Both of these attributes could be considered features, contributing to the unique look produced by this lens, and in either case the performance is improved dramatically by stopping down just one or two stops. While we can't comment on whether its performance is better than the previous version of the lens (not having yet tested it) we can say that if you need a fast, wide-angle lens for your Canon camera, you won't be disappointed with this one.

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

Still Life shot

VFA target

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.