The Wet-Plate Exposure Plan

From a meter reading to the seconds your own plates need: EV to seconds at your aperture, reciprocity corrected only past a second, your plate's real speed and your own exponent from two test plates, and the price of every stop

PlateAndFilm's ISO and EV converter is its most used tool, with a reciprocity calculator beside it. The converter ends at an EV and leaves you to pick an aperture and a time; the reciprocity calculator starts from a time in seconds. Nothing joins them, and both ask for a number you can only guess: your plate's speed, and its reciprocity exponent. Checking them for this pack, we also found the reciprocity calculator shortened sub-second times (0.38 s came back as 0.28 s); it now leaves anything at or under a second alone. The Wet-Plate Exposure Plan joins them in seven steps. It turns a meter reading into seconds at your aperture (open shade at EV 12, ISO 2: 0.78 s at f/8), corrects only what runs past a second, and replaces both guesses with two test plates: a short strip plate for your working speed and a long one for your own exponent, with a check that plugs it back in. In a window-lit room the starting guesses plan 11 s at f/4; a plate measured at ISO 1 and p 1.28 needs 26 s. It then prices every stop you close (f/4 to f/8 takes 26 s to 2 min 30 s) and logs every plate with a cost per keeper. Every figure is computed from our own calculators, and the scenes, test plates and plate cost are labelled examples. It is exposure only: no chemistry, formula or mixing, and its small print carries the safety facts for anyone who works with the chemistry. Included: 24 printable pages with seven steps, an exposure worksheet, a test plate record, a plate log, a session cost sheet, seconds and exponent reference tables and a quickstart, plus a personalised sheet worked from the numbers you enter in our ISO and EV converter and reciprocity calculator.

Look inside

Two full pages from the pack, exactly as printed. Click either to read it at full size before you decide.

What is in it

• The Meter's Speed Rule: read the EV at a speed your meter has, then shift it to the plate
• The Missing Step Rule: seconds = N squared / 2 to the plate EV, checked back to the EV
• The One Second Rule: correct only past a second, and always round up
• The Speed Test Rule: your working speed from one seven-strip plate, for each light you shoot under
• The Long Plate Rule: your own reciprocity exponent from one long test plate, plugged back in to check
• The p Stops Rule: past a second, one stop of aperture or light costs about p stops of time; never double
• The Keeper Rule: every plate logged, a cost per kept plate, and which number to change
• Four working pages: an exposure worksheet, a test plate record, a plate log and a session cost sheet
• Reference tables (seconds by plate EV and aperture, the exponent a best strip implies) and a quickstart
• A personalised sheet worked from the numbers you enter in our ISO and EV converter and reciprocity calculator

The pack picks up where the free ISO and EV converter leaves off. The converter ends at an EV; the pack turns it into seconds at your aperture, corrects only what runs past a second with the reciprocity calculator, and replaces both guesses, your plate's speed and its exponent, with two test plates of your own. The tables of the exposure planning reference become your own numbers, and a plate log shows which one to change. It covers exposure only: no chemistry, formula or mixing. Wet-plate chemistry is hazardous; learn it in person.