Useful means the angles a doctor needs: front hairline, both temples, top, and crown, in even light, hair dry and styled the way you normally wear it. That is what a doctor can assess from. If you also want to compare over time yourself, keep everything identical between sessions — same room, same light, same distance — and store them dated; but honest measurement of change is what network clinics do with GroTrack imaging.
Transcript
Four rules, and they matter more than the camera. Dry hair because wet hair always looks thinner. Overhead light, never a window behind you. The same parting each time, and the same three angles. Hairline, crown from above, and the whole top of the head. The point isn't a flattering photo. It's a photograph a doctor can compare to the next one.
Most people fail at the 'constant' part, which is why casual selfies can't answer 'is it working?'. Uberhair's guided capture holds the standards for you: the same positions, framed the same way, every time — free, from your phone, with the photos going to the doctor you choose.