Ziff-Davis Publishing Company; designed by Rauol J Hoffman. Slide-rule calculator for exposure, exterior and interior; hyperfocal distance calculator; Fo-co conversion scale, enlarging/reducing factor scale. In paper sleeve. Popular Photography Foto Fact finder 1950
Incorporating Lambert and Cadett's sliderule type exposure calculator, viewmeter partly missing, detachable exposure record (detached). The Practical Photographer's Vade Recum