I doubt it. A filter has never improved a lens for me. Filters have improved images when used to change contrast ratios, or correct color temperature. But a crappy lens or worn out coating really don't seem to be correctable. I have also experienced "improvement of images" by using a lens hood on lenses, especially older uncoated lenses... that that I consider int eh same category of improvments as mentioned above when discussing contrast or CC filters. Even a lens hood doesn't necessarily imoprove a lens but it can improve the image taken with a lens. So semantics aside of wheter filters/hoods improve the lens or the resulting images... use a lens hood on your old Leica lenses and you'll likely like the results.