Canon EF 17-40mm f/4L USM Lens

Canon EF 17-40mm f/4L USM Lens (Canon EF)
Professional Ultra-Wide-Angle L-Series Zoom – Constant f/4 Maximum Aperture, 17-40mm Full-Frame Focal Range (27.2-64mm APS-C Equivalent), One Super UD (Ultra-Low Dispersion) Element & Three Aspherical Elements, Super Spectra Multi-Coating, Ring-Type Ultrasonic Motor (USM) with Full-Time Manual Focus Override, Internal Focusing Architecture, Rounded 7-Blade Diaphragm, Weather-Resistant L-Series Construction, Dual Filter System (77mm Front Thread & Rear Gel Filter Holder), Front and Rear Caps Included, Native Full-Frame Canon EF-Mount (Good Condition)

The Canon EF 17-40mm f/4L USM is a legendary, professional ultra-wide-angle zoom lens engineered for full-frame Canon EF-mount DSLRs (and fully compatible with APS-C bodies, where it delivers a versatile 27.2-64mm standard zoom equivalent). As an established cornerstone of Canon’s prestigious L-series lineup, this optic combines expansive perspective control, edge-to-edge optical clarity, and rugged mechanical reliability. Its constant f/4 maximum aperture maintains uniform exposure settings throughout the entire zoom throw, making it a go-to workhorse for landscape photographers, architectural specialists, interior shooters, photojournalists, and travel documentarians seeking sweeping, distortion-controlled compositions.

The optical formula incorporates 12 elements arranged in 9 groups, featuring one Super Ultra-Low Dispersion (Super UD) element alongside three precision-ground aspherical elements. This advanced arrangement effectively suppresses secondary chromatic aberrations, color fringing, and spherical distortion, yielding high-contrast rendering and accurate geometric fidelity across all focal lengths. Individual surfaces are treated with Canon’s Super Spectra coating to neutralize internal reflections, flare, and ghosting when framing into direct sun or difficult backlight. Autofocus is powered by a ring-type Ultrasonic Motor (USM) paired with an internal focusing system, delivering swift, responsive, and virtually silent autofocus performance alongside instant full-time manual focus (FTM) override. In addition to a standard 77mm front filter thread, the lens features a built-in rear gelatin filter holder capable of seating up to three pre-cut gel filters, expanding creative exposure and color correction options in the field.

CONDITION DIAGNOSTICS & PHYSICAL NOTES

Included Components: ESSENTIAL ULTRA-WIDE L-SERIES OUTFIT. Supplied with the Canon EF 17-40mm f/4L USM zoom lens, Canon front snap-on lens cap, and Canon EF rear lens dust cap. (Lens hood, gelatin filters, screw-in filters, and camera bodies sold separately).

Exterior & Barrel Status: GOOD CONDITION. The black textured engineered composite barrel, iconic red L-series perimeter ring, zoom ring, and focus ring exhibit light cosmetic surface marks, edge rubbing, and finish wear consistent with standard professional field handling. All focal length markings, distance scale window text, and Canon branding remain clean, legible, and intact.

Mount Gasket Status: GOOD OPERATIONAL CONDITION (WORN RUBBER GASKET). The rear rubber weather-sealing gasket encircling the metal EF bayonet mount shows visible cosmetic wear, flattening, and minor age-related fraying along the perimeter lip. The solid metal bayonet mount seats tightly and locks securely onto camera bodies with zero mechanical wobble.

Optical Status: GOOD CONDITION. Both front and rear optical glass elements are clean and free of deep scratches, cracks, chips, haze, fungus, or cement separation. The multi-layer Super Spectra coatings remain fully intact with uniform reflection control; any minor internal micro-dust typical of vintage zoom optics does not degrade resolving power, contrast, or overall image fidelity.

Mechanical & Electronic Status: FULLY FUNCTIONAL. The ring-type USM autofocus locks onto subjects swiftly, accurately, and quietly; full-time manual focus override responds smoothly; the internal focus assembly moves without binding; the zoom ring turns smoothly across the entire 17-40mm throw with consistent resistance; the distance scale indicator tracks accurately; the 7-blade rounded diaphragm stops down cleanly without oil accumulation or sticking; gold-plated electronic contacts communicate with host Canon EOS bodies with zero error codes.

KEY FEATURES & PERFORMANCE HIGHLIGHTS

Expansive 17-40mm Ultra-Wide Range: Captures dramatic perspectives, sweeping natural landscapes, tight interior architectures, and expansive environmental portraits.

Constant f/4 Maximum Aperture: Keeps exposure levels consistent across the entire zoom range, enabling predictable manual exposure workflows.

Super UD & Aspherical Optical Elements: Features one Super UD glass element to control chromatic fringing and three aspherical elements to minimize spherical distortion.

Super Spectra Coating: Reduces internal bounce, flare, and ghosting for crisp contrast and neutral color rendition in direct sunlight.

Ring-Type USM Autofocus: Delivers high-speed, quiet, and pinpoint focus acquisition with seamless full-time manual focus override.

Internal Focusing Mechanism: Maintains a fixed barrel length during focusing, preventing front filter rotation and ensuring easy operation with circular polarizers.

Dual Filter System: Combines a large 77mm front screw-in filter thread with an integrated rear holder for up to three pre-cut sheet gelatin filters.

Rounded 7-Blade Diaphragm: Produces natural, smooth out-of-focus background blur when isolating foreground subjects at wide apertures.

Professional L-Series Build: Built with a rugged metal bayonet and weather-resistant barrel construction designed to withstand the rigors of location shooting.

Dual Caps Included: Supplied with front snap-on and rear dust caps to keep both optical surfaces protected during transit and storage.