Your camera and its modes
Every camera, from the one in your phone to a professional body, works on the same principle: a lens projects light onto a sensor for a set amount of time. What sets them apart is the size of that sensor, the quality of the optics and, above all, how much control they give you. In this lesson you'll learn to decide who makes each decision: you or the camera.
Types of camera and why the sensor matters
Phones, compacts, DSLRs and mirrorless cameras share the same logic, but not the same sensor. A larger sensor gathers more light with each shot, which means less noise when it gets dark, more dynamic range between highlights and shadows, and an easier time blurring the background.
DSLRs send the image to an optical viewfinder via a mirror that flips up when you shoot. Mirrorless cameras do without it and show the photo exactly as it will turn out in an electronic viewfinder, with its exposure and color. The major manufacturers have stopped developing DSLRs: if you're buying a camera, the logical choice today is a mirrorless one.
The camera doesn't make the photographer, but the size of the sensor does set its limits when light runs short.
The parts you'll use
You don't need to memorize the manual. These are the parts involved in every photograph and what each one controls:
| Part | What it does |
|---|---|
| Sensor | Turns light into a digital image. Its size affects noise, dynamic range and background blur. |
| Lens | A set of glass elements that forms the image. It determines the field of view and the maximum aperture. |
| Diaphragm | Blades inside the lens that control the size of the opening the light passes through. |
| Shutter | Curtains that let light through for the time you choose. |
| Viewfinder or screen | Lets you frame the shot and, on mirrorless cameras, preview the exposure. |
| Shutter button | Half-pressed, it focuses and meters the light; fully pressed, it takes the picture. |
| Mode dial | Decides which settings you choose and which the camera works out. |
The modes on the dial
Canon calls A mode Av and S mode Tv; they work exactly the same way. In every mode except auto you can set the ISO yourself or leave it on auto.
| Mode | You choose | The camera chooses | Use it for |
|---|---|---|---|
| Auto | Nothing | Everything, including flash | Moments when there's no time to think |
| P | ISO and compensation | Aperture and shutter speed | Quick shots with some control |
| A | Aperture | Shutter speed | Portraits and landscapes: you decide how much blur |
| S | Shutter speed | Aperture | Sports, animals and anything that moves |
| M | Aperture, shutter speed and ISO | Nothing | Night, studio, panoramas and constant light |
Metering and exposure compensation
In P, A and S modes, the camera measures the light in the scene and calculates the exposure assuming that everything it sees is, on average, a mid gray. It's almost always right, but it goes wrong in predictable ways: faced with snow or a white wall it darkens the photo, and faced with a black background it brightens it.
To correct this there's exposure compensation, the button or dial marked +/−. Going to +1 brightens the photo by one stop; going to −1 darkens it by one stop. It's the tool photographers who shoot in A mode use most.
With snow, dial compensation up. With black backgrounds, dial it down.
Metering modes
The light meter doesn't always analyze the same area of the frame. Every camera offers three modes, though each brand names them its own way: Nikon talks about matrix metering; Canon, evaluative; and Sony and Fujifilm, multi-segment or multi.
| Mode | What area it measures | When to use it |
|---|---|---|
| Matrix or evaluative metering | Splits the frame into many zones, analyzes them separately and compares the result with reference scenes. | The vast majority of situations. It's the default mode and the most reliable. |
| Center-weighted metering | Measures the whole frame but gives more weight to the center. | Portraits and centered subjects against a much brighter or darker background. |
| Spot metering | Only a small circle, between 1 and 5% of the frame, often tied to the focus point. | Backlit scenes, a spotlit actor on stage or the Moon: when what matters is small and lit very differently from everything else. |
Locking the exposure
Sometimes the area you want to meter isn't where you want to frame. That's what exposure lock is for, marked AE-L or, on Canon, with an asterisk: you point at the important area, press the button to hold the reading and, without letting go, reframe and shoot.
It's the classic technique for a backlit portrait: spot-meter on the face, lock, and recompose. Combined with exposure compensation, it gives you precise control without leaving A mode.
Meter where the important thing is; frame afterwards.
Why leave auto mode
Auto mode usually gets the light right, but it doesn't know your intention. It doesn't know whether you want a blurred background or a landscape sharp from front to back, or whether you're trying to freeze a jump or turn water into silk. A and S modes give you back that decision without making you calculate everything, and they're the natural step before manual.
Start in A: you choose the blur and the camera sets the shutter speed.
Recommended starting settings
Before heading out to shoot, spend ten minutes in your camera's menu. This setup is a solid starting point, widely used by professionals; over time you'll adapt it to the way you work.
| Setting | Recommendation | Why |
|---|---|---|
| Image quality | RAW + JPEG | The RAW keeps all the information for editing; the JPEG lets you share right away. |
| Shooting mode | A (aperture priority) | You control the depth of field and the camera takes care of the shutter speed. |
| ISO | Auto, with a maximum of 3200 to 6400 and a minimum shutter speed of 1/focal length | With auto ISO, the camera only raises it when the shutter speed would otherwise be too slow. |
| Metering | Matrix or evaluative | It's the most reliable in most scenes. |
| Focus mode | AF-S for still subjects; AF-C for moving subjects | Each mode handles one type of situation; you'll see this in lesson 3. |
| Focus area | Single point | You decide where the camera focuses. |
| White balance | Auto | If you shoot RAW, you can correct it later without any loss. |
| Drive mode | Single shot; burst for action | Burst multiplies your chances of catching the exact moment. |
| Stabilization | On when handheld; off on a tripod | Some stabilizers introduce small vibrations when the camera is fixed. Check the manual: many current models detect this on their own. |
| Color space | sRGB | It's the standard for screens, social media and the web. Adobe RGB only makes sense in a color-managed printing workflow. |
| Image review | Histogram and highlight warning on | They let you judge exposure without relying on the screen's brightness. |
Your turn: get to know your camera
About 20 minutes. The goal is to understand what the camera decides in each mode.
- Go through your camera's menu and apply the starting settings from the table above.
- Find your camera's mode dial, or the Pro or Manual mode in your phone's camera app.
- Pick a scene with something still and something moving, and take the same photo in Auto, A and S.
- Open each photo's details (the Info button on the camera; swipe up in your phone's gallery) and note the aperture, shutter speed and ISO.
- Photograph a white sheet of paper and a black object in A mode. See how the camera turns them both gray, and fix it with exposure compensation.