Freezing Motion and Blurring It on Purpose
Okay. Last lesson we talked about what the shutter is actually doing, mechanically, when you press the button. Today we use that. This is the fun one, honestly. This is where shutter speed stops being a number in a menu and starts being a decision you make about what a photograph should feel like.
Here's the thing about shutter speed that nobody explains well. It's not just a control for brightness. Yes, a faster shutter lets in less light and a slower one lets in more, we covered that. But the real power of it is time. Shutter speed decides how much time gets recorded in a single frame, and that changes whether motion looks frozen or smeared. Same subject, same light, completely different photo, just by changing how long the shutter stays open.
Freezing motion
If you want to stop motion cold, water splashing, a dog running, a kid on a bike, you need a fast shutter speed. As a starting point, try 1/500th of a second or faster. For something really quick, a bird taking off, a ball being thrown, go up to 1/1000th or higher if your light allows it.
Try this at home. Turn on a faucet and let it run into the sink. Set your camera to shutter priority mode (that's the S on the dial, or Tv on some Canons, don't ask me why it's Tv, I looked it up once and forgot the reason again). Set the shutter to 1/1000th and take a shot. You'll get individual drops hanging there, sharp, almost looking like glass beads. That's the shutter doing exactly what we talked about last time, just open for a sliver of time, so only a sliver of the motion gets recorded.
Now here's the catch, and it's the same catch as always. A fast shutter speed lets in less light. So you'll need either bright light, a wide aperture, or a higher ISO to make up for it. We haven't done aperture or ISO yet, one at a time, remember, so for this lesson just shoot in bright daylight or with a lamp pointed at your subject and don't worry about the rest yet.
Blurring motion on purpose
Now flip it around. Slow the shutter down and motion turns into a smear, a streak, a ghost. That same running faucet, shot at 1/15th of a second, turns into a silky ribbon of water instead of individual drops. Neither one is more correct. They're just different decisions about what you want the photo to say.
Try 1/15th or 1/8th on that same faucet. You'll need a tripod, or at least the camera braced solid on a counter, because at those speeds your own hand shake will blur the whole frame, not just the water. That's an important distinction to get straight early. Blur from your subject moving is a choice. Blur from your hands shaking is a mistake. They look almost the same on the little screen and completely different when you actually look close.
Which, by the way, is part of why I tell people to stop chimping so much, checking every single shot on the LCD right after you take it. At a glance a shaky photo and an intentionally blurred photo look the same. You have to actually zoom in on the review, or better yet look at it on a real screen later, to tell the difference. Get in the habit of checking for sharpness where it matters, not just glancing and moving on.
The story I have to tell you here
I'll be honest with you, I did not always understand this lesson as well as I'm telling it to you now.
Tami asked me to photograph her mother's 85th birthday a few years back. I felt good going in. I had it all planned, manual settings written down in my notebook, shutter speed picked out for the room, the whole thing. Everything went fine right up until the group shot at the end, the big one, everybody gathered around grandma's chair, and the flash didn't fire. I don't know why. I never fully figured it out. And because I was locked into a shutter speed too fast for the available light without the flash, I got one useable frame out of thirty. One. Everything else was too dark to save.
I apologized to that woman for a week. Tami still brings it up, and she's allowed to, because I earned it.
What that taught me, the hard way, is that shutter speed decisions are never made in isolation. You can pick the exact right shutter speed for freezing a group of people, and if something else in the chain fails, the light, the flash, your backup plan, it doesn't matter how right your shutter was. Have a plan B. If I'd checked that flash fired on an early test shot instead of trusting it, I'd have caught it in time to fix it.
Practical steps for this week
Pick one moving subject at home. Water from a faucet is easiest because you control it completely. A ceiling fan works too. Shoot it at three speeds: something fast like 1/1000th, something medium like 1/125th, and something slow like 1/15th on a tripod or braced surface. Look at all three side by side. Don't just glance, actually look close at what froze and what blurred.
Before next time: bring your three shots on your camera, or printed if you want extra credit in my book, and be ready to tell me which one you'd actually use and why. Not which one is "correct." Which one says what you wanted it to say.