We propose an objective measurement protocol to evaluate the autofocus performance of a digital still camera. As most pictures today are taken with smartphones, we have designed the first implementation of this protocol for devices with touchscreen trigger. The lab evaluation must match with the users' real-world experience. Users expect to have an autofocus that is both accurate and fast, so that every picture from their smartphone is sharp and captured precisely when they press the shutter button. There is a strong need for an objective measurement to help users choose the best device for their usage and to help camera manufacturers quantify their performance and benchmark different technologies.