Review of the Canon EF 50mm f/1.0L USM lens. With a natural angle of view and perspective, standard lenses capture the subject plainly, with no special effects. The result is different from a wide-angle or telephoto lens, which is used for more expressive purposes. At the same time, however, you can use standard lenses in creative ways by varying the subject distance, aperture and angle. Doing so requires a high level of technique and sensibility. There are three standard EF lenses, each featuring a different maximum aperture. There is the EF 50mm f/1.8 II and the EF 50mm f/1.4 USM. The latter was featured in Issue No: 2 of this column while the third standard lens in the EF line-up is none other than the EF 50mm f/1.0L USM, the subject of this issue's review. There is also a fourth lens, the EF 50mm f/2.5 Compact Macro, which is classified under the special purpose group rather than in the standard section with these three 50mm lenses. The Canon EF 50mm f/1.0L USM Standard Lens   With a maximum aperture of f/1.0, this is the world's fastest interchangeable lens for any SLR camera system. Two aspherical elements and four elements with a high refractive index contribute to excellent delineation with little flare and high contrast even at the maximum aperture. Floating elements effectively suppress spherical aberrations and curvature of field that are prone to occur at close subject distances with a large aperture lens. For natural and true color balance, special multi-layer coatings for high refraction glass have been developed for this lens. The large f/1.0 aperture gives outstanding background blur, raising the limits for photographic expressions. However, the high degree of blurriness with this lens also makes it a turn-off for most photographers who are not used to seeing such shallow depths-of-field in their photographs. Aside from the shallow depth-of-field, the lens also has a few limitations for EOS users: Vignetting may occur when it is used with the EOS-1N RS pro camera Extension tubes EF 12 and 25 cannot be used with this lens Focusing in One Shot AF mode is slow compared to other EF lenses The slower focusing speed is due to the use of the fully electronic Ring-USM originally developed for the fast aperture USM super telephoto lenses such as the EF 300mm f/2.8L USM, EF 400mm f/2.8L USM and the EF 600mm f/4.0L USM. This AF Ultrasonic motor can only be operated when the camera you are using is switched on, including manual focusing due to its all-electronic design. However, when the lens is used in the AI Servo AF mode, focus tracking of moving subjects is not a problem. << Back to Main . 1 . 2 . 3 . 4 .