These are the 3 settings you must know to master your camera

Last week I covered the three things you should do if you buy a DSLR or mirrorless interchangeable lens camera. Second and arguably most important on that list was mastering your camera's "Manual" mode. Here we're going to dive into exactly how that's done.

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In "Manual" mode, you take over the decision making for your camera. You ask yourself What am I trying to show in this image? How do I want it to look? How do I gather enough light to get the job done?

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A preseason matchup between the Philadelphia Eagles and the Pittsburgh Steelers, shot with a deliberately slow shutter. The lens swung to follow the action. Rafi Letzter/Tech Insider

The answer to all those questions rests in three settings: shutter speed, aperture (aka "f-stop"), and ISO. They all do different, important things, but each impacts how much light your sensor absorbs. If they're out of balance your shot comes out under- or over-exposed. But understand them and you can push your photography to levels impossible in "Automatic" mode.

Here's how they work.

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We'll start by exploring shutter speed.

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0.4 seconds; f/9; ISO 50 (Note: I've listed the shutter speed, aperture, and ISO numbers under each image in this slideshow where they were available. Don't worry if they don't make sense yet. By the end of this post they will.) Rafi Letzter/Tech Insider

Shutter speed is the easiest to understand of the three settings.

Think of your camera as a dark room: shutter speed is the length of time its door stays open and light flows in. The longer you leave the door open, the more the room fills with light and the brighter your image gets. Slow shutter speeds lead to brighter images. Fast shutter speeds lead to darker images.

But there's a hitch: If you leave the door open too long, the objects in your frame have time to move and can smear your image. This creates motion blur.

Shutter speed is measured in fractions of seconds, with the rare exception of cameras like the Hubble Space Telescope that need to expose for hours or days to take in enough light.

For the image above, I asked TI digital culture reporter Kim Renfro to whip her hair back and forth. Exposing for 0.4 seconds – a very slow shutter speed – her whole head appears as a featureless blob. Moments later I took another shot, this time exposed for only 1/1000 of a second.

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kim hair whip sharp
1/1000 sec; f/1.8; ISO 1250 Rafi Letzter/Tech Insider

Suddenly, Kim is frozen in time and space. (Note how I changed the other settings as well to account for the 400-fold decrease in time for light to flow in.)

Unless you want to see motion blur in your image, like in the lens-swinging football photo at the top of this page, your shutter speed should be fast enough to freeze your subject in place. Any faster and you'll likely have to compromise your ISO to get enough light (more on that later). The one exception to this rule is bright sunlight and other situations so brilliant you actually need to speed it up to keep light out of your camera.

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Here's what shutter speed looks like on my Nikon's right-side display. The number "50" means 1/50 seconds:

shutter speed
Rafi Letzter/Tech Insider

Since every camera is different, you'll need to look through your user manual to learn how to adjust shutter speed on your camera.

Here are some general rules of thumb for shutter speed:

  • Your shutter speed fraction should almost never have a lower denominator than your focal length (the "zoom" of your lens, measured in millimeters). So if you're using a 50 mm lens your shutter speed probably shouldn't be slower than 1/50 seconds, if you're using a 200 mm lens your shutter speed probably shouldn't be slower than 1/200 seconds. This keeps the shake of most peoples' hands from blurring their images in normal situations. 
  • At around 1/160 seconds your shots will freeze most normal human gestures. But don't be afraid to go slower in a dark setting if your subjects are still enough.
  • At around 1/800 seconds your shots will freeze most sports. You're going to have to go faster to stop a baseball pitch or hockey puck though.

But these aren't hard and fast rules. The better you understand shutter speed, the better decisions you'll be able to make in each situation.

Here are some images from out in the wild. Even though the room was dark, I shot this image at high speed in order to freeze every droplet in the air:

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Rafi Letzter/Tech Insider
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While for this one I slowed the shutter way down and held the camera steady in order to best capture the soft light:

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Rafi Letzter/Tech Insider

In this image the shutter speed matches the police officer, but lets the train blur:

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Rafi Letzter/Tech Insider
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The flash in this shot freezes the scene in place. A long shutter leaves a ghostly after-image in the color of the club's light:

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Rafi Letzter/Tech Insider
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Next, let's talk about aperture (aka f-stop).

aperture 1
1/400 sec; f/1.4; ISO 200 Rafi Letzter/Tech Insider

If shutter speed is the length of time your camera's door stays open, aperture is the measure of how wide it opens.

This has two key effects.

First, wide apertures allow in more light, while narrow apertures allow in less light.

Second, wide apertures leave more of a scene out of focus than narrow apertures.

The second point is a bit difficult to understand at first, but it's important. Look at the image above. See how the highlighter is in sharp focus but almost nothing else is? That's because this was shot at a very wide aperture.

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Now look at the image below:

aperture 2
1/80 sec; f/11; ISO 2000 Rafi Letzter/Tech Insider

See how much sharper the rest of the scene is? That's because the aperture is much narrower here.

You don't need to understand why this is in order to use it, but for the curious a good mental shorthand is flowing water.

Shoot a jet of water through a long, narrow opening – say, a hole drilled in a dam – and all the molecules should move in a fairly straight line after coming out the other side. In your camera, all the photons end up pretty much in order after zipping through a long, narrow aperture. So even those not focused by the lens end up somewhere close to where they "should" be.

But take some dynamite and bust that dam open and the water is going to crash all over the place. There are just more routes for water molecules to pass through an opening that broad. The same thing happens in your camera at wide apertures. Except for a very narrow band focused by your lens, the photons scatter creating a blur.

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Here's the aperture reading on my Nikon, known as an "f-stop":

aperture
Rafi Letzter/Tech Insider

As your f-stop number goes down, your aperture gets wider. That means an f-stop of f/2.8 is wider than f/3 but narrower than f/2.

Here are some things to keep in mind about aperture:

  • Wide apertures' blurring effects are more pronounced when the object in focus is closer to the camera.
  • Wide apertures can help your subject pop from the background, but you lose the context and detail of your composition.
  • Some lenses show a "vignetting" effect at their wider apertures. This is a circular shadow around the edges of your frame – an optical effect of the glass in your lens. Some people like it. Some people don't. Instagram filters usually add fake vignetting. 
  • Make sure your aperture is narrow enough that you can keep your subject in focus as it moves. The fastest sports photographers may shoot wide-open, but the rest of us have to compromise.
  • Better lenses have wider maximum apertures than cheap ones. Many top-tier primes go as wide as f/1.4, and most good lenses go as wide as f/2.8. Junky kit lenses often contract from f/3.5 to f/5.6 or narrower as you zoom in.
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In this shot, I kept the aperture narrow to keep all four actors' expressions in focus:

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Rafi Letzter/Tech Insider

While in this one I opened the aperture wide to see the fencer's expression through her blurred-out mask:

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Rafi Letzter/Tech Insider
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For headshots, I usually aim for a middle ground:

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The last important camera setting is ISO.

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1/1000 sec; f/9; ISO 25,600 Rafi Letzter/Tech Insider

Look at the camera settings for this image. The shutter only opened for 1/1000 of a second, and the aperture was only f/9. That means that light had just a sliver of time to slip through a pinprick into the camera. So how did this shot of the Tech Insider newsroom (half-empty for lunch) not come out completely black?

The answer is ISO, or the sensitivity of the camera's sensor.

When your camera is set to a high ISO, it absorbs more light. When your camera is set to a low ISO, it absorbs less light. It's an easy way to brighten or darken an exposure without changing your shutter speed or aperture.

Of course, there's one big honking disadvantage to just raising your ISO every time you walk into a dark room. The higher the ISO of your image, the grainier it comes out.

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Here's an image shot in the same lighting as above, but with the aperture and shutter speed adjusted to allow for a much lower ISO:

low iso
1/50 sec; f/2.8; ISO 400 Rafi Letzter/Tech Insider

Generally, more expensive cameras add less grain for each step up the ISO ladder. Here are some basic guidelines for working with ISO:

  • Under-exposed images tend to be grainier than over-exposed images at the same ISO.
  • On a professional-tier camera, grain should stay within acceptable levels until about ISO 3200
  • On a quality consumer DSLR, grain should stay within acceptable levels until at least ISO 2000
  • Most cell phones and other point-and-shoots show serious graininess after around ISO 800
  • If you're shooting in the studio or outdoors during daytime, keep your ISO to your camera's minimum – usually 100 or 50.

Here's what the ISO reading looks like on my camera. I have to hold down an "ISO" button to make it appear.

ISO
Rafi Letzter/Tech Insider

I bump my ISO up most often when shooting news, where I have no control over a scene's timing or lighting.

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This hard-right Israeli settlers' march through an Arab neighborhood in East Jerusalem took place well after midnight.

israel settler rally high iso
Rafi Letzter/Tech Insider

Most of the settlers kept their backs to the bright streetlights – as did the police. You can see grain in the images, but my wide-open aperture leads to a bright enough exposure that it's not overwhelming:

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Rafi Letzter/Tech Insider
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Let's review!

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Rafi Letzter/Tech Insider

Shutter speed is the length of time a picture is exposed. Slow shutters let in more light but allow motion blur. Fast shutters let in less but prevent motion blur.

Aperture is the measure of how wide a lens opens for a picture. Wider apertures let in more light and have a narrower plane of focus.

ISO is the sensitivity of your camera's sensor (or of a roll of film) to light. Higher ISO comes with more grain.

Go forth and capture the world in your lens.

Photography
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