If you take a picture of a Raspberry Pi 2 with a strong flash it will reboot.
A specific power regulator (U16) was chip-scale packaged to save on cost and die space.
Since the silicon is basically naked, a xeon flash can cause a massive (but very short) current spike.
Naked silicon (specifically, WLCSP) isn’t “bad” per se; it’s heavily used in mobile phones.
The thing is…phones are usually sealed. The Pi is an exposed development board.
Don't blame the engineers too hard, Apple actually had a similar issue with the iPhone 4 (back glass).
The fix for the RPi is a bit obvious of course.
either:
1. don’t do that (take pictures with high powered flash inches away) 2. if you must…put a little blu-tak, nail polish, or other opaque inert substance on U16