Tools · ALPE Key
The ALPE Key.
A complete reference glossary for the Area Lighting Positional Equation system — every abbreviation, its reference name, and its variable. Search, scan, or print.
Arch of Light
Positions run A through V around the subject in an arc, with numbers 1–6 marking line-of-sight width after the letter (e.g. )=G/4, )=EF/3). Top/bottom positions use a single letter with an OH (overhead) or UC (under carriage) prefix — e.g. OH)=M, UC)=V.
Angles & R3D
Angles are measured 0°–180°, from the light's Arch position aimed at the subject's R3D position. R3D (Rule of Thirds 3D) is the subject/camera's position, written letter+number (e.g. E5, A7, H9) — E5 is always the absolute center, and all distances in an equation are measured from it.
Dissecting Line
DS)= marks when multiple lights run in a line across the Arch — each is numbered clockwise: DS)=L1, DS)=L2, and so on.
Example Equation
CM = L14-55mm/fm37mm @ s125 f11 A100 )=G/4 H4.5' x D8' R3D~E5 (fltr=ND.02)
— Camera Settings Abbreviations
— ALPE Key