Good bang for the buck. Works on full frame or C sensor cameras. So small it makes even the biggest camera usable anywhere. Good in low light , no flash situations, and auto focus works quite well.

The EF 40mm f/2.8 STM is a fairly unprepossessing little lens, and its tiny size and relatively low price might make you wonder whether significant compromises have been made in its design and construction.

Very good optics; Tiny size; Silent autofocus; Responsive electronic manual focus; Decent construction; Low price

Can be susceptible to flare; No lens hood supplied; AF speed isn't the fastest

The EF 40mm F2.8 STM offers excellent image quality in a tiny, well-made package. For APS-C users it provides a great carry-everywhere complement to a kit zoom, and for full frame shooters it's an excellent general-purpose 'normal' lens. The STM motor means that autofocus is almost completely silent, but it's not super-fast.

Canon SLR owners who want the image quality of a prime in a tiny, relatively inexpensive package.;

Photographers shooting in really low light or aiming for maximum background blur. They'll do better with a faster lens like the EF 50mm F1.8 II;

The Canon EF 40mm f/2.8 STM ($199.99 direct) lens is one of the smallest you'll find for Canon cameras . Its pancake design barely juts out from a camera when mounted. It can be used on full-frame and APS-C D-SLRs, and provides smooth autofocus for video recording when paired with the EOS Rebel T4i...

Extremely compact; Very sharp; Minimal distortion; Inexpensive; STM focus motor

Focus-by-wire design; Modest f/2.8 aperture

Super images, especially considering the size and price. On an APS-C body, it's a 60mm "normal" lens that's biting sharp wide open, edge to edge. Keep it in your front pocket. On full frame it's a little soft wide open, but still charming. I hope Canon continues to make lenses like this.

Awesome "normal" lens for APS-C

Focus a little slow

Fantastic lens for the price and weight.

I didn't buy the nifty fifty due to its somewhat low build quality. So when this lens was announced in the 'cheap enough not to really worry' price bracket, I snapped one up. I think with the EF 40mm pancake, Canon have the balance right. It's not an 'L' lens but does have a metal mount.

I love this lens. I prefer to use prime lenses over zoom lenses and I bought this lens to replace the "nifty fifty" that was recommended to me when I bought the camera body. This lens is a much higher quality and takes better images. The auto focus mechanism is also a lot more responsive.

High quality construction; compact size; amazing price

Nothing

I should say this is a great value for what it is: a sub-$200, fast 40mm EF lens with well regarded sharpness stats even wide open. Where the EF 40mm f/2.8 STM is a huge letdown is in the realm of video. There is distinct and audible autofocus hum that is recorded on your video.

A great walk around that is perfect for low light situations. This is a lens you will be happy with because of its STM abilities,of its weight and the quality of construction and picture quality.