Just posted: Our review of the Canon EF 40mm f/2.8 STM lens. In the latest of our lens reviews brought to you in partnership with DxOMark, we take a look at Canon's slimline 'pancake' prime for its APS-C and full frame SLRs. It's one of the smallest and cheapest lenses currently on the market, and includes a stepper motor for silent focusing during movie recording. But does its small size and low price result in compromised optics? Read our review to find out.