An alt-process exposure happens in an environment that's tricky for a phone: your hands are wet, you're handling an opaque mask on a glass plate, you're laying down and lifting sensitized sheets in the darkroom. You don't want to have to tap a screen five times to set three minutes. You want one gesture, a dial that responds, and an audio signal that tells you when it's done.
Calibration Flow's timer looks like the dial on a smart speaker. A large OLED circle, a duration needle, and you set it with your finger by dragging on the ring. No numeric keypad, no millimeter-precise slider — a physical dial under the touch, with a notch at each step that you feel as much as you see.
#What you see
You open the timer from the Target module or from the Tools menu. At the center of the screen, a large circular dial — black background, orange needle, duration shown as
MM:SSPrecision changes with the duration range. It's built around the real orders of magnitude of alt-process exposures:
- 0 to 3 minutes — 15-second steps. For cyanotypes in the sun or short test strips.
- 3 to 6 minutes — 30-second steps. This is the standard range for most processes under the Luminograph.
- 6 to 30 minutes — 1-minute steps. For long platinotype exposures or weak UV sources.
You can pick a timer mode (countdown that rings at zero) or a stopwatch mode (counts up from zero with no upper limit). Beyond 30 minutes, the dial saturates — you have to chain several timers or move to a dedicated external tool.
You can run several timers in parallel. A "cyanotype #1" timer running while you prepare the second sheet with a "preparation" timer telling you how long until you should start the second exposure. Each timer has its own countdown and you can attach a text note to it (a word, a reference to the print in progress) that stays with it until you clear it.
A mini progress ring appears on the main navigation button as soon as a timer is active. Whatever app screen you're on — Target module, Curve module, library — you always see where your main timer stands. You don't need to return to the timer screen to check.
When the count reaches zero, the app plays a sequence of musical notes (a rise then a resolving chord) and vibrates the device. You hear it and you feel it — you don't have to look at the screen.
#Why it matters
For exposures in the darkroom or a wet environment. The dial adjusts with a single dragged gesture — no repeated tapping, no millimeter precision demanded. You can set it with your eyes closed once you know the steps, just by the vibration. It's the tool that lets you keep both hands for the photography while the timer does its work.
For batch production. The parallel multi-timers let you expose three sheets staggered by 30 seconds, each with its own countdown. The mini ring on the nav tells you which one will come out first without having to navigate. That's what turns a session of four sequential prints into four prints in parallel.
For long unattended sessions. You start an 8-minute timer, you go answer the phone in another room. At zero, the iPhone vibrates and plays the sound — you know it's time to come back, even from afar.
#When you don't need it
A single occasional exposure. A kitchen timer does the job just as well. The dial is built for regular practice where the fine adjustments and the multi-timers save real time.
In very variable natural light (sun). 15-second precision on a natural source that can change in a few seconds as a cloud passes is cosmetic. Note the duration to the nearest minute and accept the variability — or move to a controlled UV source if you want reproducibility.
If you're after a sequence of exposures at doubling intervals (1 min, 2 min, 4 min, 8 min — the classic harmonic-step test strip). This automatic mode does not exist in the current timer. You can do the sequence by hand by restarting the timer between each step, but the app won't automatically trigger the following steps.
#Key facts
| Element | Value |
|---|---|
| Duration range | 0 to 30 minutes |
| Precision 0-3 min | 15-second steps |
| Precision 3-6 min | 30-second steps |
| Precision 6-30 min | 1-minute steps |
| Modes | Timer (countdown) or stopwatch (count-up) |
| Multi-timers | Yes, independent, with text notes |
| Progress ring | Always visible on the nav when active |
| Feedback | Short vibration at each notch, musical chime at zero |
#The test
Start a 5-minute timer. Lock your iPhone and put it in your pocket. After exactly 5 minutes (within 1-2 seconds), the device should vibrate in your pocket and play the chime. If you feel nothing after 5 minutes, either vibration is disabled in your iOS settings, or the timer was interrupted in the background — check the "Notifications" permission for Calibration Flow.