Chapter 6 is Adams getting brutally practical about the shutter: it’s not a “setting,” it’s a time-gate—and if you don’t respect how it actually behaves, your craft gets sloppy fast.

Chapter 6 — Shutters: The Time Gate You Keep Forgetting You’re Using

A lot of photographers (especially in the digital era) treat shutter speed like a vibe slider: faster freezes, slower blurs, done. Adams agrees that shutter speed shapes motion, but he starts one layer deeper: the shutter’s job is simply to control how long light is allowed to hit the recording medium—and everything else we talk about hangs off that one fact.

He even drops a little history lesson to remind you that “precision” is earned: he recalls literally using a lens cap as a shutter in the early days, and how quickly photography demanded real mechanisms as materials got faster and expectations got higher.

Exposure isn’t mysterious. It’s a relationship.

Adams puts exposure back into a clean equation:

• Exposure = Intensity × Time (E = It)

Time is the shutter. Intensity is what actually reaches the film (and yes, aperture plays a role in that). Then he points out the part that still matters in 2026: once you know the “right” exposure, you can swap shutter speed and aperture in predictable steps because both systems are built in doubling/halving increments (one stop).

That’s the backbone of confidence in the field: you’re not guessing—you’re choosing which compromise you want.

Leaf vs focal-plane: two designs, different consequences

Adams breaks shutters into the two big families:

• Leaf shutters (in the lens) open and close with blades. They’re mechanically elegant, but there’s a practical ceiling on their fastest times because the blades have to complete a full open-then-close cycle.
• Focal-plane shutters (in the camera body) use curtains travelling across the film plane; their behaviour isn’t affected by aperture in the same way leaf shutters are.

This isn’t trivia—it’s why two cameras at “the same shutter speed” can behave differently in the real world.

Flash sync isn’t a footnote—it’s a constraint

One of the most modern-feeling parts of the chapter is how he explains flash timing problems in plain language:

• With electronic flash, the flash duration can freeze motion, but if ambient light is strong and your shutter is slow, you can get a sharp flash image with a faint secondary “ghost” from the ambient exposure.
• Sync limits matter, and leaf shutters have an advantage because they can synchronize at faster speeds than focal-plane shutters in many designs.

Even if you never touch a flash, the deeper point holds: every tool you add has timing rules, and the shutter sits at the center of them.

The uncomfortable truth: shutters aren’t “perfect”

Adams makes it explicit: an ideal shutter would open instantly, stay fully open for the exact interval, and close instantly. Real shutters can’t do that. So he introduces shutter efficiency—how close reality is to the ideal—and explains why efficiency worsens at very fast speeds (because opening/closing time becomes a large fraction of the total exposure).

He goes further with a detail most people never think about: with a leaf shutter, effective timing can change with aperture because a small opening is uncovered more quickly than a large one—so efficiency rises as you stop down. He even mentions choosing a “pivotal” stop (such as f/16) when evaluating leaf-shutter accuracy in view-camera work.

That’s such an Adams move: “You want consistency? Then define where you measure it from.”

The final (and most human) lesson: how you press the button matters

Then he ends with something that feels almost like a coach grabbing your wrist:

• Don’t jab the release.
• Apply steady pressure.
• Use a cable release when you can, and don’t let tension in the cable transmit vibration.

This is the craft part people skip because it’s not sexy—and it’s exactly why their negatives (or files) don’t hold up when they zoom in later.

My 2026 takeaway

Chapter 6 is Adams saying: stop treating shutter speed as a preference and start treating it as a mechanism with behaviour.

Yes, today’s cameras give us electronic shutters, stabilization, and a safety net of instant review. But the underlying discipline is the same: understand what the shutter is actually doing, pick the tradeoff you want (motion, sync, sharpness), and execute cleanly.

Next up for me: Chapter 7 — Basic Image Management—where the conversation shifts from “how the camera works” to “how you think with it.”