I accidentally knocked off and lost an SMD labelled "C9" from the Raspberry Pi Camera. The Camera still works, and I am unable to spot any differences. What is the role of the capacitor, and is it needed for proper operation of the camera?
The OP accidentally knocked off a SMD component labelled C9 from his Rpi Camera. But his camera is working "perfectly" without any noticeable difference. How come?
Well, usually in an electronics circuit, not all components are critical. If any one or more of those not critical components are removed, the system often still works, with or without any noticeable differences.
Rpi Camera Circuit Analysis
I googled the schematic as shown in Appendix A. Then I searched for any component labelled C9 and happily found it hiding in the very middle of the picture. Now I have put relevant circuit below for discussion.
I think the SMD component labelled C9 is just an external 1uF bypass for the voltage regulator of the 24MHz clock generator. The voltage regulator usually has its own physically smaller bypasses. So the external bypass cap is not that critical.
Discussion and Recommendation
The SMD Bypass cap C9 for both V1.3 and V2.1 are easy to access. So it might be a good idea to replace the lost cap with an external one, say a through hole electrolytic/tantalum 1~10uF. Just use two jump wires to hang the external guy outside/nearby, instead of in place.
Warning: I am just a friendly hobbyist. No guarantee that no nothing won't melt down or blow up. Good luck.
Appendix A - Rpi camera schematic
Appendix B - Rpi Camera Components