Schaaff Mosaic Diagrams

A type of Pseudoisochromatic Plate developed by Frenchman D. Schaaff in 1925. Instead of numerals, it is based on the Landolt C (Landolt ring), which is the same principle used in the Colorlite online tests (link).

Dechromatized Colorlite Landolt-C style Pseudoisochromatic Plate