Cell type: Optical/Extinction
Measure type: Reflecting / Averaging
Another extinction meter. I'll try and photograph this sometime with some backlighting to illuminate the reading scale in the window. You hold this thing horizontally, much like a Weston Master, and the light passes through a small slit window and illuminates a letter scale marked A through G. Each letter is increasingly dense, so as the light becomes progressively brighter, additional letters become visible.
The calculator is a two-step affair; two dials, and inner (red) and an outer (black and white). You start with the inner dial and set the pointer up against your film speed (which tops off at ASA 200, which says something about how old this is). Then you pick the lighting condition on the outer dial (e.g. "Bright") and put its pointer next to the letter that's just barely visible on the scale. So for instance, at ASA 100, a bright day set at letter E gives you 1/100th @ f/11.
Nice meter. It's shaped to fit the hand nicely, and the calculator window is fairly easy to read.
This was also sold as the Da-Brite, though I have no other information on that version, or why it was done.