I just got myself a cheap USB microscope. It is great fun to test on all sorts of things. It has a very bright light on the front and comes with a small stand.
Here is a plain flat image of my new Asterix film. The film seems to be in a very good shape, although I haven't projected it yet.
Here is the balance track and a sprocket hole. The light is titled a bit, and that's when the fun starts as we get the tiny tiny stripes and uneven surface visible:
But the fun starts when tilt the light a lot more:
These are not all stripes, but mostly shows that the surface is much more uneven than it seems when we look at it with the eye or with a direct fron/back light. Keep in mind: this looks like a very nice copy, and any uneven bump or any stripe will look very extreme under this lighting!
Here is the sound stripe:
What impresses me more than anything is the accuracy of which the sound stripe and sprocket holes are made. I know it has to be like that to get a steady picture, but when you see the accuracy under a microscope it is still fascinating.