Incorporating Lambert and Cadett's sliderule type exposure calculator, viewmeter partly missing, detachable exposure record (detached). The Practical Photographer's Vade Recum
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