The Exposure Triangle
Three settings that control how bright your photo is
Aperture
Controls how much light enters through the lens. Also affects how much of your image is in focus (depth of field).
Shutter Speed
Controls how long light hits the sensor. Affects motion blur—fast speeds freeze action, slow speeds create blur.
ISO
Controls sensor sensitivity to light. Higher ISO brightens the image but adds grain/noise.
The Balancing Act
These three settings work together. If you change one, you often need to adjust another to maintain the same exposure. For example, if you want a faster shutter speed, you might need a wider aperture or higher ISO to compensate.
Aperture
The eye of your lens
Aperture is measured in f-stops (like f/1.8, f/4, f/11). Here's the counterintuitive part: smaller numbers = bigger opening. Think of it like fractions—1/2 is bigger than 1/8.
Interactive Demo
Wide Open (f/1.8)
Maximum light, shallow depth of field. Great for portraits with blurry backgrounds.
| Aperture | Light | Depth of Field | Best For |
|---|---|---|---|
| f/1.4 – f/2.8 | Lots of light | Very shallow (blurry background) | Portraits, low light, artistic blur |
| f/4 – f/8 | Moderate light | Moderate depth | General photography, groups |
| f/11 – f/22 | Less light | Deep (everything sharp) | Landscapes, architecture |
Shutter Speed
Freezing or flowing time
Shutter speed is measured in seconds or fractions of a second. 1/1000s is very fast (freezes action), while 1/30s is slow (can show motion blur).
Interactive Demo
Fast Shutter (1/1000s)
Freezes fast motion completely. Great for sports and action.
| Speed | Effect | Best For |
|---|---|---|
| 1/1000s and faster | Freezes all motion | Sports, birds, fast action |
| 1/250s – 1/500s | Freezes most motion | Kids, pets, street photography |
| 1/60s – 1/125s | Slight blur possible | Walking people, general use |
| 1/30s and slower | Motion blur, needs tripod | Waterfalls, light trails, night |
ISO
Sensitivity vs. quality
ISO amplifies the signal from your camera's sensor. Higher ISO = brighter image, but also more digital noise (grain). Modern cameras handle high ISO better than older ones.
Interactive Demo
Low ISO (100)
Cleanest image quality, minimal noise. Use in bright conditions.
General Rule
Keep ISO as low as possible for the cleanest images. Only raise it when you can't get enough light with aperture and shutter speed alone.
Focal Length
How much of the scene you capture
Focal length is measured in millimeters (mm). It determines your field of view—how "zoomed in" your shot appears. Smaller numbers = wider view, larger numbers = more zoomed.
Interactive Demo
| Focal Length | Type | Field of View | Best For |
|---|---|---|---|
| 10–24mm | Ultra Wide | Very wide, some distortion | Architecture, landscapes, interiors |
| 24–35mm | Wide | Wide, natural look | Street, environmental portraits |
| 50mm | Standard | Similar to human eye | General purpose, portraits |
| 85–135mm | Short Telephoto | Compressed, flattering | Portraits, events |
| 200mm+ | Telephoto | Narrow, distant subjects | Wildlife, sports, moon |
Prime vs Zoom Lenses
Fixed focal length or flexible range?
Prime Lenses
Fixed focal length (e.g., 35mm, 50mm, 85mm). You "zoom with your feet" by moving closer or farther.
Pros: Sharper, wider apertures (f/1.4, f/1.8), lighter, often cheaper
Cons: Less versatile, need to swap lenses
Zoom Lenses
Variable focal length (e.g., 24-70mm, 70-200mm). Twist the barrel to zoom in or out.
Pros: Versatile, convenient, one lens for many situations
Cons: Heavier, smaller max aperture, often pricier for quality
Beginner Recommendation
Start with a versatile zoom (like an 18-55mm kit lens), then add a fast prime (like a 50mm f/1.8) to learn about shallow depth of field and low-light shooting. The "nifty fifty" is affordable and teaches you a lot.
Depth of Field
What's sharp and what's blurry
Depth of field (DOF) is the zone of acceptable sharpness in your photo. A shallow DOF has a thin slice in focus (blurry background), while a deep DOF keeps everything sharp.
Interactive Demo
Three factors affect DOF:
| Factor | Shallow DOF | Deep DOF |
|---|---|---|
| Aperture | Wide (f/1.8, f/2.8) | Narrow (f/11, f/16) |
| Distance to subject | Close to subject | Far from subject |
| Focal length | Longer (85mm, 200mm) | Shorter (24mm, 35mm) |
About Bokeh
"Bokeh" (from Japanese) refers to the aesthetic quality of the blur in out-of-focus areas. Smooth, creamy bokeh is often desirable in portraits. It's influenced by the lens design and the shape of the aperture blades.
Crop Factor
Sensor size matters
Not all camera sensors are the same size. "Full frame" sensors are 36×24mm (same as 35mm film). Smaller sensors crop the image, making lenses appear more zoomed in.
| Sensor Type | Crop Factor | 50mm Lens Equivalent | Common In |
|---|---|---|---|
| Full Frame | 1.0× (baseline) | 50mm | Pro cameras (Sony A7, Canon R5) |
| APS-C (Canon) | 1.6× | 80mm | Canon Rebel, M series |
| APS-C (Others) | 1.5× | 75mm | Nikon DX, Sony a6000, Fuji X |
| Micro Four Thirds | 2.0× | 100mm | Olympus, Panasonic |
What This Means
If you put a 50mm lens on an APS-C camera, you get the field of view of a 75-80mm lens on full frame. This is great for telephoto (wildlife gets "free" reach) but can make wide-angle shooting harder.
Image Stabilization
Steadying the shot
Stabilization compensates for camera shake, letting you shoot at slower shutter speeds without blur. There are two main types:
Optical Image Stabilization (OIS)
Built into the lens. A floating element moves to counteract shake. Works with any camera body.
Look for: IS (Canon), VR (Nikon), OSS (Sony), OIS (Panasonic/others)
In-Body Image Stabilization (IBIS)
Built into the camera body. The sensor itself moves. Works with any lens, including older ones.
Common in: Sony, Canon R series, Nikon Z, Olympus, Fuji
The Rule of Thumb
Without stabilization, your minimum handheld shutter speed should be 1/(focal length). So with a 50mm lens, try to stay at 1/50s or faster. Stabilization can give you 3-5 stops of leeway—meaning 1/10s might be possible handheld with good IS.
White Balance
Getting colors right
Different light sources have different color temperatures, measured in Kelvin (K). White balance adjusts your image so whites look white, not orange or blue.
| Setting | Kelvin | Use For |
|---|---|---|
| 🕯️ Tungsten/Incandescent | ~2700K | Indoor bulbs (removes orange cast) |
| 💡 Fluorescent | ~4000K | Office lighting (removes green cast) |
| ☀️ Daylight | ~5500K | Sunny outdoor conditions |
| ☁️ Cloudy | ~6500K | Overcast days (adds warmth) |
| 🌑 Shade | ~7500K | Open shade (adds warmth) |
| ⚙️ Auto (AWB) | Varies | General use—camera decides |
Shoot RAW
If you shoot in RAW format, white balance can be changed later in editing software with no quality loss. JPEGs "bake in" the white balance, making it harder to fix later.