Enlarger Timer

What Is a Darkroom Enlarger Timer?

An enlarger timer controls the duration of light projected through a negative onto photographic paper in a darkroom. Precise, repeatable exposure timing is the foundation of consistent black-and-white and color printing. This free digital enlarger timer offers three modes — simple timed exposure, f-stop based timing, and sequential test strips — replacing the mechanical GraLab and foot-switch timers found in traditional darkrooms.

Whether you are making your first contact sheet or fine-tuning a gallery print with complex dodge-and-burn sequences, accurate exposure control eliminates guesswork and reduces paper waste. Set your base time, choose your mode, and let the timer handle the counting while you focus on the craft of printing.

F-Stop Printing Explained

Traditional darkroom timers count in linear seconds, but photographic paper responds logarithmically to light. Adding 2 seconds to a 5-second exposure is a massive 40% increase, while adding 2 seconds to a 25-second exposure is a barely visible 8% change. F-stop printing solves this inconsistency by using geometric (doubling/halving) increments that produceperceptually uniform steps across the entire exposure range.

In f-stop mode, each increment is a fraction of a stop — 1/3 stop, 1/2 stop, or 1 full stop. A 1/3 stop increase multiplies the exposure by approximately 1.26x. A full stop doubles it. This scaling means a 1/3-stop adjustment looks the same whether your base exposure is 4 seconds or 40 seconds, making exposure decisions intuitive and repeatable.

Making Test Strips with F-Stop Timing

The test strip mode in this timer automates the sequential exposure process used to determine optimal print exposure. Instead of additive strips (where each section accumulates all previous exposure), f-stop test strips give each section a geometrically increasing total exposure:

1. Set your base time — Start with an estimated exposure (10 seconds is a common default for 35mm negatives at f/8).
2. Choose your increment — 1/3 stop gives fine control for final prints; 1/2 or 1 full stop gives a wider range for initial tests.
3. Set the strip count — 5-7 strips covers a useful range. The timer calculates the exposure for each strip automatically.
4. Expose and evaluate — Process the strip normally, then examine it under proper viewing light. The strip with the best highlight-shadow balance indicates your target exposure.

Dry-Down Compensation

Fiber-based silver gelatin papers darken as they dry — a phenomenon that catches many printers off guard. A wet print that looks perfect in the wash can appear noticeably too dark once it has dried on a screen or in a heated dryer. The typical dry-down shift is 5-12%, depending on paper brand and surface finish. Glossy papers tend to show more dry-down than matte.

This timer includes a configurable dry-down compensation percentage (default 8%) that automatically reduces your calculated exposure to account for the darkening. Enable it when printing on fiber paper; disable it for RC (resin-coated) papers, which exhibit minimal dry-down.

Dodging and Burning with Precise Timing

• Dodging (holding back light) — Use a card or wire-mounted mask to shade areas that print too dark. Calculate dodge time as a fraction of base exposure in f-stop terms: -1/3 stop means shading for about 20% of the exposure time.
• Burning (adding extra light) — After the main exposure, give additional time to areas that need more density. +1 stop of burning doubles the exposure in that area. Use your hands or a card with a hole to direct light.
• Keep records — Note your base exposure, dodge times, and burn times in f-stop increments. This makes it easy to reproduce a print or make controlled adjustments. Pair this timer with our film development timer to maintain precision across your entire darkroom workflow.