8. Operating the ΔStop

This section covers each operating mode in detail. It assumes you've read Section 5 (Anatomy) and have a working knowledge of the controls. If you've skipped ahead, the Quick Start in Section 4 will get you oriented faster. A video demonstration of the ΔStop in use is available at https://www.youtube.com/watch?v=eNQ6Frt7SIs.

The ΔStop has three operating modes, selected by the Mode dial: Focus, Test, and Print. Program Memory is available across all modes. Each is covered below in the order you'll typically use them during a printing session.

Focus Mode

Focus mode turns on the enlarger lamp continuously so you can compose, focus, and evaluate your negative on the easel.

To use Focus mode, turn the Mode selector to Focus. The enlarger lamp turns on immediately and stays on as long as the dial remains in the Focus position. Turn the dial away from Focus to turn the lamp off.

No button press is required. The lamp follows the dial directly. This is deliberate: focusing is a tactile, continuous activity, and asking you to press Start every time you want to see your negative would interrupt the rhythm of the work.

When you are finished focusing, turn the Mode selector to Test (or Print, if you are bypassing the test strip workflow). The lamp will turn off, and the ΔStop will be ready for the next step.

Test Mode

Test mode is where you make test strips. The ΔStop runs an automatic sequence of exposures, each separated by the fractional stop interval you've selected.

To make a test strip:

Turn the Mode selector to Test.
Set the Base Time dial to your starting exposure. For a fresh negative at f/8, 30 seconds is a forgiving default. For a negative you've printed before, use your previous work print time as the base.
Set the Test Interval dial to the fractional stop step you want. A 1/2-stop interval covers the widest range and is best for a first pass on an unfamiliar negative. A 1/4 or 1/8-stop interval covers a narrower range with finer precision and is best for refining after a first strip has narrowed your target.
Place a strip of paper on the easel.
Press Start. The enlarger lamp turns on. Expose the first section for the first interval.
Cover 1/7th of the paper, and press Start again. The enlarger lamp turns on.
Repeat Step 6 again covering more of the paper each time until you've made 7 exposures
The time display shows the time remaining in the current interval while the strip is running. When the full sequence completes, the lamp turns off and the display returns to the base time setting.

If you need to stop a test strip mid-sequence, press the Start/Stop button again or press Reset. Reset returns the ΔStop to the beginning of the sequence for the current base time and interval settings.

The Two-Strip Workflow in Practice

Most printing sessions use two test strips per negative. The first strip establishes the neighborhood of the correct exposure; the second strip refines within that neighborhood.

For the first strip, use a 1/2-stop interval. This gives you a wide enough exposure range that even an imprecise base time guess will capture the correct exposure somewhere on the strip. Develop the strip, evaluate it under white light, and choose the band that looks closest to what you want.

For the second strip, set the Base Time dial to the exposure time of the winning band from the first strip.

The second strip brackets your best guess with fine precision. The correct exposure almost always falls on this strip, usually within one or two bands of center.

Some printers stop at 1/4-stop refinement; others go to 1/8 for delicate tonal work. There is no single right answer. Use the finer interval when the print asks for it and save the paper when it doesn't.

Print Mode

Print mode makes the final print exposure. It uses the Base Time and Print Stop Select dials together to calculate a single timed exposure.

To make a print:

Turn the Mode selector to Print.

Confirm that the Base Time dial is set to the exposure time you chose from your refined test strip.

Turn the Print Stop Select dial to 0 if you want the final print to match the base time exactly. If your test strip told you the print wants to be half a stop lighter, turn the dial to -1/2 (or the nearest available marking and adjust the base time to compensate). If the print wants to be a full stop heavier, turn the dial to +1.

In most cases, if you've already refined your test strip, the Print Stop Select dial will stay at 0 for the first print and move only if you want to experiment with a variant.

Place a fresh sheet of paper on the easel. Press Start. The ΔStop exposes the paper for the calculated time. When the exposure completes, the lamp turns off and the display returns to the base time.

Using Program Memory

Program Memory stores complete timing configurations for later recall. Each of the three memory banks holds a base time, test interval, and print stop selection.

To store the current configuration, press Set, then press 1, 2, or 3 to choose the bank.

To recall a stored configuration, press 1, 2, or 3. The dials on the faceplate do not move, but the stored values take effect internally. The display shows the recalled base time, and subsequent exposures use the stored configuration until you either turn a dial (which overrides the stored value) or recall a different bank.

Program Memory is most useful in two situations:

First, during a session where you are printing several variants of the same image. Store the base configuration in bank 1, then experiment with contrast or burning times in bank 2, and keep a third variant in bank 3. You can move between them without losing any of your dialed-in work.

Second, across sessions where you are returning to a known negative. If you printed an image last week and expect to print it again, store the configuration before you pack up. Next session, recall the bank and you are back where you left off.

Memory banks persist across power cycles. They are not cleared by pressing Reset, which only cancels the current running timer.

Resetting the Current Timer

The Reset button cancels any exposure in progress and returns the ΔStop to its ready state for the current mode. Use Reset when you realize mid-exposure that the paper is misaligned, the easel has moved, or a setting is wrong.

Reset does not clear Program Memory. It does not change any dial position. It simply stops the current timer and waits for your next input.

With these modes understood, you have everything you need to work through a complete printing session. Section 9 covers tips and refinements that make a real difference once the core workflow is familiar.