Canon 17-40mm f/4L USM (EF)

The EF 17-40mm f/4L USM Lens from Lightbulb Rentals is a versatile wide-angle zoom lens that belongs to Canon's prestigious L-series. It features a constant f/4 maximum aperture, ensuring consistent illumination throughout its zoom range. This lens is designed for full-frame Canon EF-mount DSLRs but can also be used with APS-C models, providing an equivalent focal length range of 27.2-64mm.

Optically, the lens incorporates one Super Ultra-Low Dispersion (UD) glass element and three aspherical elements. These elements work together to minimize chromatic and spherical aberrations, resulting in high sharpness, clarity, and accurate color reproduction. A Super Spectra coating has been applied to reduce flare and ghosting, enhancing contrast and maintaining color neutrality, especially in challenging lighting conditions.

The EF 17-40mm f/4L USM utilizes a ring-type Ultrasonic Motor (USM) and an internal focusing mechanism, enabling fast, precise, and quiet autofocus performance. It also offers full-time manual focus override for fine-tuning focus manually even when autofocus is engaged.

Built with durability in mind, this lens is weather-sealed to protect against dust and moisture, making it suitable for use in various environmental conditions. It features a rounded seven-blade diaphragm that contributes to pleasing out-of-focus areas, beneficial for achieving shallow depth of field and selective focus effects.

Furthermore, the lens includes a rear filter holder that can accommodate up to three cut gel filters, in addition to the standard 77mm front filter ring, adding versatility to its use in different shooting scenarios. As a member of Canon's esteemed L-series, the EF 17-40mm f/4L USM lens is well-regarded for its optical excellence, robust construction, and versatility, making it a reliable choice for photographers seeking high-quality wide-angle imagery.