The electricians have a nice little spiral bound pocketbook, perhaps 70 sheets, 3x5 inches just full of tables, formulas and hints. (its actually called "Ugly's Handbook"). Machinists have the machinist handbook, and the pocket version Seems like there's a book of "stuff" like that, formulas, light trig, weights and measures available at the big box stores. So, is there a small pocket guide for photography? Bellows factor, exposure info, Filter factors, perhaps the back cover inside at 18% grey,,, a two inch round circle on one page to calculate magnification with a view camera... Stuff like that?