Most of the time it is quite apparent when someone is about to make a photograph, their camera is at eye-level, and their finger is poised over the shutter release button. We do not always want to send out this signal so we need to employ a more discrete technique. Having your camera strap around your neck with the camera hanging in front of you does not suggest that you are about to make a photograph, particularly if you are looking straight ahead rather than down at your camera. Also, a smaller and less noticeable camera does not attract attention in the way that a big DSLR does. I made this image last month at the street market in Victoria BC using this technique. Not being able to frame the image via the view finder means there is definitely an element of hit-or-miss, something that adds to the fun. A wide angle lens that you can pre-focus to the hyperlocal distance according to the aperture setting is helpful. An aperture setting of f5.6 or f8 will work well. This will give you enough depth of field to ensure the image appears sharp from just in front of the camera all the way to the background. You need to turn autofocus off for this to work. Unfortunately, very few modern lenses are equipped with functional depth of field scales, something that makes setting hyperfocal distances a little more difficult. Depth of field charts are available for free online, and there are smart-phone apps to calculate DOF and hyperlocal distances. This is a very useful technique to master, not just for candid photography.
Fuji X-E1, 14mm f2.8 lens at f5.6, 1/400 sec at ISO 200.