The Canon EF 17-40mm f/4L USM Ultra-Wide Zoom Lens (Black) is designed with a wide-angle range, & is one of Canon's L-Series zoom lenses. The EF 17-40mm Ultra-Wide Zoom features a constant f/4.0 maximum aperture, a high quality optical design, & is designed to have a durable construction. In order to help reduce chromatic & spherical aberrations for high sharpness, clarity, & color accuracy, one super UD element, & three aspherical elements are featured in the lens' design. The lens also features a Super Spectra coating to reduce flare & ghosting, improving the contrast of your images in difficult lighting conditions. This wide-angle zoom is also designed with a ring-type USM, & internal focusing mechanism to help provide fast, quiet, & accurate autofocus performance (& full-time manual focus override). Its weather-sealed physical design enables use in difficult environmental conditions.
Other Features:
- Wide-Angle Zoom: Designed for full-frame Canon EF-mount DSLRs (Compatible with APS-C models with a 27.2-64mm equivalent focal length range).
- Maximum Aperture: Constant f/4 aperture (maintains consistent illumination throughout the zoom range).
- Elements: One Super Ultra-Low Dispersion glass element is included to reduce color fringing & chromatic aberrations for clarity & color fidelity. Three aspherical elements are used to minimize spherical aberrations & distortions for improved sharpness).
- Super Spectra Coating: This coating is applied to individual elements to minimize ghosting & flare (greater contrast & color neutrality).
- Ultrasonic Motor (USM): A ring-type USM, along with an internal focusing system, is featured to deliver fast, precise, & quiet autofocus (& full-time manual focus override).
- Seven-Blade Diaphragm (Rounded): Contributes to a bokeh quality (out of focus) that helps control shallow depth of field/selective focus techniques.
- Rear Filter Holder: A front 77mm filter ring, & rear filter holder are also featured (for three cut gel filters).
