Here's an odd question. I bought a number of lenses as a lot and there was included a tiny longish lens that was un recognizable as a lens because it was obscured with dirt. So I cleaned it. It is mainly brass, with a functioning aperture so it's a camera lens I guess, but it also has what appears to be a copper part to the barrel. Was copper used with brass for lenses? It looks oldish and very small. Certainly not a large format lens but I was curious if anyone has seen a mix of metals on lenses

Don't have it with me so no picture to show but could post one later if anyone is interested