The Canon EF 17-40mm f/4L USM Lens is a high-performance ultra-wide-angle zoom lens designed for full-frame and APS-C DSLRs. With its constant f/4 maximum aperture and compact, lightweight build, it is ideal for a range of photographic applications, from landscapes to architecture.
Key Features:
- Ultra-Wide to Standard Zoom: Provides a versatile 17-40mm focal length range, functioning as an ultra-wide-angle zoom on full-frame cameras and a standard zoom equivalent to 28-70mm on APS-C DSLRs.
- Constant f/4 Aperture: Maintains a consistent aperture throughout the zoom range for even exposure and depth of field control.
- Optical Performance: Features 12 lens elements in 9 groups, including three aspherical elements and Super UD (Ultra-low Dispersion) glass to reduce chromatic aberrations and ensure sharp, high-quality images. Super Spectra coating minimizes ghosting and flare, enhancing color balance and contrast.
- Fast and Quiet Autofocus: Equipped with a ring-type ultrasonic motor (USM) for quick, silent autofocus, with full-time manual focus override for precise control.
- Close Focusing: Offers a minimum focusing distance of 28cm across the entire zoom range, allowing for detailed close-up shots.
- Non-Rotating Front Element: The front element does not rotate, making it easier to use filters like polarizers and grads. A drop-in gelatine-filter holder is also available.
- Smooth Background Blur: A virtually circular aperture diaphragm creates a pleasing, smooth background blur (bokeh) for professional-looking images.
- Weather Resistance: Built to withstand dust and moisture, making it suitable for challenging shooting environments. Constructed with lead-free glass for environmentally friendly performance.
The Canon EF 17-40mm f/4L USM Lens combines exceptional optical quality with a durable, weather-resistant design, making it a reliable choice for landscape and architectural photography. Its wide zoom range, constant aperture, and robust construction provide versatility and performance, while the advanced autofocus and close focusing capabilities enhance its utility in various shooting conditions.
