What the Shutter Is Actually Doing
Okay. New module. We've spent four lessons on manuals and dials and the exposure comp thing, and now we're actually getting into settings that change your picture. Good time to start.
Here's the thing. I said a few lessons back that everybody wants to learn the whole exposure triangle in one sitting, aperture and shutter and ISO all at once, and I told you that doesn't work. It doesn't. So we're doing shutter speed first, on its own, and we're not touching the other two dials for a couple weeks. I know that's slow. It's supposed to be slow.
What shutter speed actually is
Your camera's shutter is a little curtain in front of the sensor. When you press the button, it opens, lets light hit the sensor for a certain amount of time, and closes again. Shutter speed is just how long that curtain stays open.
That's it. That's the whole concept. Everything else is what you do with it.
Fast shutter speed, like 1/1000 of a second, means the curtain is open for a blink and barely any light gets in. Slow shutter speed, like 1/15 or a full second, means it stays open longer and lets in a lot more light.
The reason this matters for your pictures isn't really about brightness though, even though that's what's happening technically. What you'll actually notice, and what you'll actually use this for, is motion. Fast shutter freezes motion. Slow shutter shows it moving, blurs it, drags it across the frame. Same subject, wildly different photo, and shutter speed is the dial doing that.
Try this at home
Find something moving. Doesn't have to be exciting. Water running out of your kitchen faucet works fine, or your dog if it'll cooperate, or cars going by if you're near a road (stand somewhere safe and sensible, don't lean into traffic for a photo, I mean that plainly).
Put your camera in shutter priority mode, which on most Canons is Tv and on most Nikons is S. That mode lets you set the shutter speed and the camera handles aperture for you. We're not doing full manual yet, one thing at a time.
Shoot the same moving subject at a few different speeds. Try 1/1000, then 1/125, then 1/15, then if your camera lets you go slower, try a full second. Look at what happens to the water or the dog or the cars. At the fast end everything's frozen, sharp, almost looks paused. At the slow end things start to smear and blur.
Neither one is correct. That's the part people get hung up on. A frozen drop of water off a faucet is a specific choice and a blurred sheet of water is a different specific choice, and you get to decide which one you want depending on what you're going for.
The tripod problem
Once you get down around 1/60 or slower, handheld shots start getting blurry from your own hands shaking, not just from the subject moving. That's not artistic blur, that's just camera shake, and it ruins the shot. If you want a slow shutter speed and a sharp non-moving background, you need a tripod, or at minimum something solid to brace the camera against. A porch railing works. A fence post works. I've used the hood of my truck more than once.
Opinion time, since I've got one
I'll be honest with you, I think people obsess over getting the perfect shutter speed for a scene and end up missing the shot entirely while they're dialing it in. I've told this class before and I'll say it again: a slightly wrong photo you actually took beats the perfect photo you missed while fiddling with the dial. Get something. Adjust from there. You can't fix a moose that already left the meadow.
The scrub oak thing
I want to tell you about a mistake, because it's a good one and it wasn't about shutter speed at all, but it's the same lesson in a different shape.
I hiked up American Fork Canyon one October to shoot a stand of scrub oak that was doing that deep orange thing they do for about ten days a year if you catch it right. Spent a whole morning up there. Got home, pulled up the photos, and every single frame was blown out, overexposed, the color gone flat and washed. Every one. Two hours of shooting, ruined.
Turned out I'd bumped my exposure compensation dial with my thumb early on and never noticed, because I wasn't checking my settings, I was just shooting and trusting the camera to keep doing what I told it an hour earlier. It wasn't.
The reason I bring it up here is that shutter speed has the exact same trap. You dial in something that works for one shot, get absorbed in the scene, and don't notice your settings drifted or the light changed or your subject started moving faster than you accounted for. Check your screen sometimes. Not constantly, we'll talk about chimping and why I think it's overdone in a later lesson, but check it sometimes.
Before next time
Shoot the same moving thing at least four different shutter speeds before our next session and bring your favorite one, even if it's not the technically "correct" choice. I want to see what you liked, not what the textbook says you should've liked.