iPhone... holding a drop light in my left hand, zoom in a little with the right hand, move the light around as needed to get the edges to show up. For REALLY small stuff (like the watch parts I tinker on in my "spare" time), I put a jeweler's loupe in front of the camera lens and it works great. Even a cheapo $10 loupe from Harbor Freight works like gangbusters.

Now if I can get the carb on my leaf blower rebuilt, I might have some time to tinker on the diffs again...

Clair