The Canon EF 40mm f/2.8 STM is the lens that makes a DSLR or adapted RF body feel less like a production rig and more like a camera you can just take with you. It is small, sharp, and cheap. The autofocus is not the fastest, but that is not really the point.

I bought mine used a few years ago, mainly for my Canon Elan 7, to turn it into an everyday camera. It is the lens I reach for when I do not want to carry a full kit, when I am going out for something other than photography, but still want a camera with me other than my phone.

40mm used to be this odd, nice focal length that almost nobody paid attention to. Nowadays, it feels much trendier. But before falling into the trend, it is worth renting or borrowing a 40mm first, because it is not for everyone, especially if you plan to use it as your only focal length during a shoot or a trip.

If you like the field of view, though, you quickly realize you can do a lot with it.

The Good:

• Tiny size makes the whole camera easier to carry.

• Surprisingly sharp for the price and form factor.

• 40mm is a natural, flexible field of view.

• STM focus is smooth and quiet, though not the fastest.

• Cheap enough to be a low-risk everyday lens.

• Great fit for Canon autofocus film bodies and compact DSLR setups.

• Available in white as a somewhat limited edition.

The Bad:

• f/2.8 is not very fast for a prime.

• No image stabilization.

• STM focus-by-wire is less tactile than a mechanical focus ring.

• 40mm can feel awkward if you are strongly used to 35mm or 50mm.

• Get it if you want the smallest useful EF full-frame lens.

• Get it if you want a cheap, sharp, normal-ish everyday prime.

• Get it if compact carry matters more than speed.

• Pass if you plan to use it mostly on RF camera.

• Pass if you’re hoping to use it for video.