Canon EF 40mm f/2.8 STM

• Specifications
• Reviews
• Product Advisory

Canon's first pancake lens in the EF range. The somewhat unusual 40mm focal length gives 64mm equivalent on a 1.6 crop sensor body.

First introduced in 2012, the lens features a quiet STM (stepper motor) drive for AF and 'Movie Servo AF' for smooth, quiet autofocus when filming on compatible Canon DSLRs.

Initial indications are that the lens is very good optically

Available from: Amazon.com | Amazon.co.uk | B&H | Adorama

Lens specifications

Focal Length & Maximum Aperture	22mm, 1:2
Lens Construction	7 elements in 6 groups
Diagonal Angle of View	63°30'
Focus Adjustment	Inner Focusing System
Closest Focusing Distance	0.49 ft. / 0.15m
Filter Size	43mm
Max. Diameter x Length, Weight	2.4 x 0.9 inch, 3.7 oz. / 60.9 x 23.7mm, 105g

Construction

MTF compared to 50/1.8 and 50/1.4

A quick guide to MTF charts (which only measure contrast and resolution. Canon's guide to their MTF charts) Black lines reflect lens performance at widest aperture. Blue lines show the performance at f/8 Thick lines indicate lens contrast Thin lines indicate lens resolution Dashed lines: Lens performance with meridional lines. Solid lines: Lens performance with sagittal lines Closer sagittal and meridional chart lines indicate more 'natural' out of focus areas. Remember that MTF charts are good for comparing similar lenses, so comparing ones from the 14mm f2.8L and 300mm 2.8L won't tell you much at all, whilst comparing the EF14 2.8L with the EF14 2.8L II will show meaningful differences. Note that other manufacturers may have different ways of displaying such information that may or may not match up with the Canon figures.

Which 400mm? - a list of all versions

Canon EF 400mm
Attribute	f/2.8 USM	f/2.8 II USM	f/2.8 IS USM	f/2.8 IS II USM	f/2.8 IS III USM	f/4 DO IS USM	f/5.6 USM	f/4 DO IS II USM
Key features
Full-frame compatible	Yes
Image stabilizer	No		Yes				No	Yes
Ultrasonic Motor	Yes
L-series	Yes
Diffractive Optics	No					Yes	No	Yes
Technical data
Aperture (max-min)	f/2.8-f/32					f/4-f/32	f/5.6-f/32	f/4-f/32
Construction	9 groups / 11 elements		13 groups / 17 elements				6 groups / 7 elements	12 groups /18 elements
Aperture blades	8			9		8		9
Closest focusing distance	4m		3m	2.7m	2.5m	3.5m		3.3m
Max. magnification	0.11x		0.15x	0.17x		0.12x	0.11x	0.13x
Diagonal viewing angle	6 °
Physical data
Weight	13.44 lb / 6.1 kg	13.03 lb / 5.91 kg	11.83 lb / 5.37 kg	8.48 lb / 3.85 kg	6.26 lb / 2.84 kg	4.27 lb / 1.94 kg	2.8 lb / 1.25 kg	2.1 kg
Maximum diameter	6.57" / 167mm		6.41" / 163mm			5.03" / 128mm	3.54" / 90mm/	5.04" /128mm
Length	13.70" / 348mm		13.74" / 349mm	13.50" / 343mm		9.16" / 232.7mm	10.09" / 256.5mm	9.16" / 232.7mm
Filter diameter	48mm		52mm drop-in filter				77mm	52mm drop-in
Accessories
Lens hood	ET-161B II		ET-155	ET-155 (WII)	ET-155 (WIII)	ET-120	Built-in	ET120 (WII)
Case			400	400C	400E	400B		400D
Retail information
Release date	April 1991	March 1996	Sept. 1999	Aug. 2011	Sept. 2018	Dec. 2001	May 1993	Sept. 2014

EF 40mm f/2.8 STM reviews and articles

• Canon UK | US Information Page
• Amazon
• Canon CPN article
• Lens manual (PDF)
• Firmware update via Canon USA
• Fred Miranda
• Digital Picture
• PhotoZone
• SLR Gear
• ePhotozine

Written a review? Contact us and we'll add it to the list.

Product Advisory notice (August 2012)

To Users of the EF40mm f/2.8 STM Interchangeable Lens for Canon Digital SLR Cameras
Thank you for using Canon products.

It has been confirmed that the autofocusing function of the EF40mm f/2.8 STM lens, which was released in June 2012, may not operate correctly.

The details of this phenomenon are described below.

Affected Product
EF40mm f/2.8 STM

Phenomenon
If pressure is applied to the lens barrel while the lens is mounted to the camera (pressure can be applied even while attaching the lens cap or while carrying the camera with the lens attached in a bag), the autofocusing function of the lens may stop working.

*This phenomenon does not occur during normal shooting.
*This phenomenon does not result in a malfunction of the lens.

Workaround
When the above phenomenon occurs, detach and reattach the lens, or remove and reinsert the camera battery to restore the operations.

Market Support: The firmware to address this phenomenon will be available for download in late August, 2012.

Comparison of size between 40mm and 50mm Canon lenses