Why now?

The Show HN launch drew 83 points, indicating real interest from the film photography community, and the author's own framing shows the pain point is current: proper f-stop timers still cost hundreds of dollars while a phone plus a $20 smart plug can do the timing. The app is solo-built with no exotic hardware or AI dependency, so the approach is replicable now.

The gap

Commercial advanced f-stop timers are expensive (hundreds of dollars per the author), and no cheap phone-plus-smart-plug alternative is established. The gap is a software layer that turns commodity hardware into darkroom timing, but the data shows only a niche community signal (83 HN points) — broader demand is not proven.

Main competitor

Dedicated commercial f-stop enlarger timers that cost hundreds of dollars, as cited by the author. No direct software competitor is evidenced in the provided signals.

Execution plan

1. Build a phone app that controls a cheap smart plug over the local network, matching the core feature set described: regular timing, f-stop timing, test strips, and dodge/burn.
2. Abstract the smart-plug layer behind a small adapter interface so multiple plug brands/APIs can be supported and a broken third-party API does not kill the app.
3. Ship to the film photography community where the Show HN post already found an audience, and collect feedback on which plug models and enlargers work.
4. Add offline/local-only operation and calibration helpers so the app works without cloud accounts and tolerates network quirks in a darkroom.
5. Decide on a one-time paid app or tip-jar model, since the signals show no evidence of recurring-revenue willingness to pay.

Monetization

One-time paid app or tip jar. The signals show a low willingness to pay for a utility app and no recurring-revenue path; the value proposition is avoiding a several-hundred-dollar timer, so price well below that. No market-size or revenue projections are supported by the data.