I attached a cell phone fisheye adapter lens to my Hubsan X4 H107C quadcopter/drone and flew it around for a bit. Most camera mods involve disassembly and possible damage, but this mod is harmless. This footage is color corrected but has not been stabilized.
This is definitely the cheapest and simplest camera fix mod you can do for this little quad. All you need is a $3-$5 cell phone adapter lens kit, some strong clear tape, electrical tape to mask off the light leaks, and careful hands to line the adapter rear up with the direction of the camera. The results speak for themselves. The lens flare is inevitable because the lens adapter has uncoated elements.
After this video, I added a thin rim of electrical tape sticking out of the front edge of the lens to cut down on lens flare from sunlight outside of the visible area. I don’t know if it helps but it certainly can’t hurt.