Canon EF 40mm f/2.8 STM
max. magnification 0.18x
also usable on APS-C
Canon EF 40mm f/2.8 STM is a compact standard prime lens made by Canon for cameras with the Canon EF mount. The lens is designed for full-frame Canon EOS cameras and can also be used on APS-C cameras, where its field of view becomes narrower and is roughly equivalent to a 64 mm lens on full frame.
The model belongs to the pancake lens category: it is 68.2 mm in diameter, 22.8 mm long, and weighs about 130 g.[1] Canon notes that at the time of release it was the thinnest and lightest lens in the EF series, and that the STM drive made autofocus smoother and quieter than lenses using a simple DC motor.[1]
The Canon EF 40mm f/2.8 STM sits between classic 35 mm and 50 mm prime lenses. On full-frame cameras it is suitable for walk-around, street, everyday, and documentary photography, while on APS-C cameras it behaves more like a short portrait lens.
Lens usage
Advantages
The main advantages of the Canon EF 40mm f/2.8 STM include:
- Compact size. The lens barely increases the size of the camera and is convenient for travel, walks, and everyday shooting.
- Low weight. At about 130 g, it is one of the lightest Canon EF lenses.
- Full-frame and APS-C compatibility. Unlike the Canon EF-S 24mm f/2.8 STM, this lens uses the EF mount and can be mounted on full-frame Canon DSLR cameras.
- f/2.8 aperture. The wide aperture helps with indoor and evening photography and can produce moderate background blur.
- STM focusing. The stepping motor provides smoother and quieter focusing, useful for video on compatible cameras.
- Close focusing distance. The 0.3 m minimum focusing distance makes it possible to photograph small objects and details close up.
Limitations
The limitations of the lens include:
- No optical image stabilization. In low light, the photographer must watch shutter speed, raise ISO, or use a stable shooting position.
- No zoom. Framing is done by moving the photographer or by cropping the image later.
- Moderate lens speed. f/2.8 is better than many kit zooms, but slower than fast f/1.8 or f/1.4 prime lenses.
- Not a macro lens. The maximum magnification is about 0.18x, so the lens is useful for close-ups but not for true 1:1 macro photography.
- Focus-by-wire operation. As with many STM lenses, manual focusing is electronic and requires the camera to be powered on.
Lens characteristics
Focal length
A 40 mm focal length gives a natural, moderately wide field of view on full-frame cameras. It is slightly wider than a classic 50 mm lens and produces less perspective exaggeration than 24-28 mm wide-angle lenses. This field of view is useful for street photography, travel, family scenes, product shots, and environmental portraits.
Canon lists the angle of view as 57°30′ diagonally, 49°20′ horizontally, and 34° vertically.[2] On APS-C cameras the field of view becomes narrower, so the lens is often perceived as a short portrait prime.
Focusing
The lens uses a stepping STM autofocus drive. It is designed for smooth and relatively quiet operation, which is important for video. Canon also lists full-time manual focusing as one of the lens features.[1]
Because of the compact body, the focusing ring is narrow, but autofocus is usually sufficient for everyday photography. When shooting fast-moving subjects, the lens may be less responsive than more expensive USM models, but it is adequate for walk-around, family, product, and travel photography.
Chromatic aberrations
Chromatic aberrations appear as coloured edges along high-contrast borders. On the Canon EF 40mm f/2.8 STM they are usually moderate and are most often visible when the image is enlarged, for example around water highlights, branches, metal details, or bright contrast edges.
Examples of aberrations are shown below:
- Chromatic aberrations of the Canon EF 40mm f/2.8 STM
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Photograph taken with the Canon EF 40mm f/2.8 STM -
Aberrations become visible when the image is enlarged
At normal viewing size the image looks clean, and small aberrations can also be reduced during processing.
Bokeh and background blur
On full-frame cameras the lens can produce moderate background blur when used close to the subject at f/2.8. However, 40 mm and f/2.8 do not produce as much bokeh as 50 mm f/1.8, 85 mm f/1.8, or faster portrait lenses.
On APS-C cameras background blur can still be noticeable in portraits and detail shots, but the field of view becomes narrower, so the lens may be less convenient in tight indoor spaces.
Distortion and vignetting
The Canon EF 40mm f/2.8 STM has moderate optical imperfections typical of compact lenses. Slight distortion is usually not distracting in everyday scenes, but it may be visible in architecture and straight lines. Vignetting is more likely at wide aperture and on even bright areas of the frame.
Most of these imperfections can be corrected in the camera or in image-editing software.
Close-up photography
The minimum focusing distance is 0.3 m, and the maximum magnification is about 0.18x.[2] This is suitable for food, flowers, small objects, and detail shots, but it does not replace a dedicated macro lens.
Examples of close-up shooting:
- Close-up photography with the Canon EF 40mm f/2.8 STM
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Close-up photograph taken with the Canon EF 40mm f/2.8 STM -
Cropped image
Sample photographs
- Sample photographs taken with the Canon EF 40mm f/2.8 STM
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Issyk-Kul -
Eastern Issyk-Kul -
Eastern Issyk-Kul -
Eastern Issyk-Kul -
Issyk-Kul
Overall assessment
The Canon EF 40mm f/2.8 STM is a successful compact prime lens for owners of Canon EF and EF-S cameras. Its strengths are very small size, low weight, full-frame compatibility, f/2.8 aperture, and a practical focal length for everyday photography.
The lens is especially useful as a lightweight alternative to a kit zoom or as a compact walk-around lens. It does not replace a fast portrait lens, a dedicated macro lens, or a professional reportage zoom, but it works well as a simple, light, and good-quality everyday lens.
Other Canon lens articles
References
- ↑ 1.0 1.1 1.2 EF40mm f/2.8 STM. Canon Camera Museum.
- ↑ 2.0 2.1 EF40mm f/2.8 STM — Specification. Canon South & Southeast Asia.