This 8.5" x 11" white photographic paper variable density target offers a convenient means of testing the gray level performance of optical systems. There are 15 density steps from a density of 0.09 to 1.5 on two progressions from high to low and low to high. This corresponds to optical density increments of 0.10. The variation between density steps is linear, which leads to a logarithmic change in diffuse reflectivity. Since a logarithmic reflectivity progression offers both finer and coarser incrementation than a comparable linear chart, it is often preferable for system testing. Paper is 0.2mm thick. White matte photographic paper.