f vs DisparaTimer

The f-Stop Printing Calculator allows darkroom printers to modify times by stops when calculating exposure values. The calculator will establish 1/4 stop increments (+ or – up to 3/4) of the base time you have entered and, either generate a new time, or an increment of an f-stop if you are burning in. By working with f-stops rather than linear units of time, you can produce an easier to read test strip as the exposure differences are exactly equal. This app has been designed by Digitaltruth Photo Ltd and Bruce Tanner.

DisparaTimer is a mobile app that, when connected to a Raspberry Pico W/WH, can control the exposure time of a photographic enlarger using a power relay. The physical setup is inexpensive and easy to assemble. DisparaTimer has two operation modes. The first is a traditional timer mode, where you set a specific time for each exposure. The second is designed for creating test strips with constant fractional step increments over a base time. On iPad (iPadOS 17 and later), DisparaTimer includes a landscape-only notes panel that lets you add photos or images of your test strips and make handwritten or visual annotations directly on them.