Canon 40mm


Canon 40mm f2.8 stm lens review

Canon 40mm f2.8 Stm




Technical specifications:

Dimensions:68.2×22.8 mm

Weight:130 g (4.59 oz.)

Optical formula: 6 elements in 4 groups, very simple design not many contrast robbing elements

Minimal focus distance: 25 cm (0.82′)

Filter size: 52 mm

Focus limiter: No

Tripod mount: No


Canon 40mm f2.8 stm lens is a relatively new lens in the Canon lineup. The Canon 40mm is a pancake lens, which is quite common for example in Pentax lineup. The “pancake” name refers to the shape of the lens which is flat like a pancake not long as the usual lenses. The lens construction is quite simple not includes lots of contrast robbing elements.

What is this Stm motor ?

Canon’s new Stm motor is optimized for video recording. First it is perfectly silent in practical terms, more silent than the USM drive. Second it is optimized for smooth transitions so important for video recording. But we haven’t seen the stm motor in high end Canon lenses yet.

Build quality:

The build quality of the 40mm lens is good. The lens is not rotating, but the physical length of the lens is changing during focusing, similarly like the Canon 50mm f1.4 for example. The pancake construction is certainly very desirable, but compare to Milc cameras, such as Olympus or Panasonic we normally cannot put this lens in our pocket even mounted on the smallest Canon 100 D Dsrl, while this is possible with the earlier mentioned Models.

Optical quality:

The Canon 40mm lens is very nice straight from the f2.8 aperture. The lens is very sharp, has nice colours and contrast. Interesting news that this lens gives extraordinary sharpness on the newest 50.6 megapixel Canon 5ds dslr. Not every lens gives the same result, for example one tilt shift lens suffer on 50.6 megapixel.

canon 40mm

canon 40mm

Canon 40mm f2.8 stm on Canon 550d f2.8 iso 100 1/200s no sharpening as it came from the camera


Canon 40mm f2.8 stm on Canon 550d f2.8 iso 100 1/1250s no sharpening as it came from the camera


100% crop of the above picture 5184 pixel jpeg


100% crop of the above picture 5184 pixel jpeg

Focal length:

Perhaps the real question about this lens is the focal length. Do we need this extra lens, what extra it can gives to the existing ones ? Two thing to consider is our budget, what we need and which format camera we have. I think the 40mm is very useful on a FF frame camera where some vignetting is expectable at wide open aperture. At Aps-C camera the focal length is not the best, but better than the 50mm for example. If not the brightness is our first priority this lens can serve as a street photography or close portrait or group portrait lens. The small length makes this lens very desirable.


Canon 50/1.8 II, Canon 50/1.4, Canon 35/2, the first two lens has a significant advantage is their much brighter aperture, the 35/2 is also brighter but not very sharp at f2, while the 40mm sharp at f2.8 the build quality, smaller size and better autofocus, and manual focus mechanism of the 40mm perhaps makes more desirable. On Aps-C cameras according to me the 40 mm is better than the 50mm, almost like a normal lens (30mm). For landscapes this focal length on Aps-C perhaps not wide enough. Meanwhile Canon will release the Canon 24mm is stm.


Sharp, small, light, stm motor optimized for video, not very expensive. f2.8 brightness.


Stm motor is not optimized for older cameras, only Canon 650d is optimized for stm lenses, vignetting on full frame

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