Canon EF 40mm f/2.8 STM Lens (AS-IS)

Canon EF 40mm f/2.8 STM Lens
Ultra-Slim “Pancake” Walkaround Prime with Smooth STM Autofocus
The Canon EF 40mm f/2.8 STM is a remarkably compact, low-profile “pancake” prime lens designed for full-frame and APS-C format Canon EF-mount DSLR cameras. Measuring less than one inch thick, this sleek, short-normal lens provides an incredibly portable footprint that is perfect for everyday walkaround shooting, street photography, travel, and discreet documentation.

By balancing its modest f/2.8 maximum aperture with advanced aspherical glass, a gear-driven STM stepping autofocus motor, and a versatile field of view, this lens delivers a sharp and nimble option for both high-resolution stills and fluid video tracking.

WELL-USED / AS-IS CONDITION NOTE
Please read the following structural and optical evaluation carefully before purchasing. This lens is listed under Well-Used Condition and is being sold strictly AS-IS for parts, repair, or budget-conscious projects:

Cosmetic Imperfections: The lens body exhibits clear signs of heavy field use. There are visible cosmetic scuffs, scratches, and finish wear localized around the front face of the manual focus ring.

Internal Glass Inclusions (Dust & Fungus): There is a moderate accumulation of internal dust particles, alongside visible fungus spores spreading along the outer edges of both the front and rear glass element groups.

Real-World Imaging Performance: The internal fungus and dust do not affect your photographs. Thorough optical testing confirms that because these flaws rest completely along the outer edges and completely outside the lens’s native plane of focus, they cannot resolve onto your camera’s digital sensor. Your final images remain sharp and clear. However, please note that a mild loss of overall micro-contrast or faint internal lens flare may occur if shooting directly into intense, unshaded studio lighting or a blinding sunset.

Value Proposition: If you need a hyper-portable, working STM lens for rough field environments where gear might get banged up, or if you want to clean vintage-style glass elements yourself, this lens represents a massive savings opportunity. All sales are final.

Included Accessories
Front Lens Cap

Rear Lens Cap

Expanded Optics & True Constant Speed
Dynamic Short-Normal Reach: Delivers a highly versatile 40mm perspective on full-frame Canon EF-mount bodies, serving as a sweet spot between a standard 50mm and a wide-angle 35mm lens. It is also fully compatible with crop-sensor APS-C models, where it provides a 64mm equivalent focal length.

Modestly Bright f/2.8 Aperture: The f/2.8 maximum aperture allows you to maintain stable exposure parameters in low-light environments, facilitates clean handheld shooting, and delivers a shallow depth of field with creative selective focus separation.

Advanced Optical Aspherical Control: Built with one precision aspherical element designed to aggressively limit geometric distortions, field curvature, and spherical aberrations, ensuring high sharpness and accurate rendering.

Super Spectra Coating Shield: Treated with Canon’s advanced multi-layer Super Spectra Coating to minimize ghosting, surface reflections, and internal lens flare, preserving rich contrast and color neutrality.

Rounded Seven-Blade Diaphragm: Outfitted with a 7-blade circular aperture array that produces a smooth, visually pleasing background blur (bokeh) when leveraging shallow depth-of-field techniques.

Gear-Driven STM Autofocus & Portable Design
Smooth STM Stepping AF Motor: Powered by an internal STM stepping autofocus motor that couples with a rear focus system, advanced AF algorithms, and a high-speed CPU. This mechanism delivers quick, precise, and near-silent autofocus tracking optimized for both static portraits and professional, jitter-free video capture.

Ultra-Slim Pancake Form Factor: Measures less than one inch thick and weighs next to nothing, turning even heavy full-frame DSLR bodies into highly discreet, travel-ready setups.

Technical Specifications
Lens System Classification: Ultra-Compact Pancake Standard Prime Lens

Lens Mount Type: Canon EF Mount (Full-Frame DSLR and APS-C Compatible)

Focal Length: 40mm (64mm equivalent on Canon APS-C sensors)

Maximum Aperture: f/2.8

Minimum Operational Aperture: f/22 via Electronic 7-Blade Rounded Diaphragm

Filter Thread Diameter Size: 52mm

Lens Optical Layout: 6 Elements configured in 4 Groups (Includes 1 Aspherical Element)

Autofocus Motorization Gearing: STM Stepping Motor with Full-Time Manual Override

Focusing Infrastructure System: Rear Focusing Design

Minimum Object Focus Distance: 11.81 inches / 30 cm

Maximum Magnification Ratio: 0.18x

Aperture Blade Count: 7-Blade Diaphragm (Rounded Layout)

Dimensions (Diameter x Length): Approx. 2.69 x 0.90 inches / 68.2 x 22.8 mm

Weight: Approx. 4.6 oz / 130 grams (Featherlight, pocketable travel footprint)