[Rol_Lei Nut]

Anyway, I do have some "legacy" lenses with a web of fine scratches on the front element. Some have unmentionable things lurking inside as well, but none of them appear to be affected by any of this in actual use.

Though, the only way to really tell if it makes a difference would be to compare the results with those from the same lens in pristine state (hoping sample variation doesn't play a role).

A loss of contrast often won't be noticed unless directly compared with a contrastier image.