1. Welcome

Thank you for choosing the ΔStop 100.

This timer was built for printers who want their darkroom work to be repeatable, precise, and a little more joyful. It operates on f-stop principles, which means every adjustment you make corresponds to a photographic stop rather than an arbitrary number of seconds. If you've ever made a test strip in linear seconds and wondered why the step between 8 and 10 seconds looks so different from the step between 20 and 22, you already understand why f-stop timing matters. The ΔStop handles that math for you, so you can focus on the print in front of you instead of the arithmetic behind it.

The design is deliberately quiet. A single time display, a small number of dials, and one large Start button. Every control has one job. Nothing on the faceplate is there to impress you; everything is there because it earns its place during a printing session. The goal was a tool that disappears into your workflow after the first few prints, the way a good enlarger or a familiar loupe does.

Whether you are doing your first printing session or you've been in the darkroom for decades, this manual will walk you through what the ΔStop does, how to use it, and how to get the most from the workflow it enables. The core operation can be learned in a single printing session. The craft of f-stop printing, like the craft of printing itself, is a longer conversation, and one worth having.