1.1 What Is Exposure?
Imagine you’re filling a glass with water. If you pour too little, it’s not satisfying. If you pour too much, it overflows.
Exposure is the same idea — but with light.
In photography, exposure is simply the amount of light that hits your camera’s sensor. Too little light, and the image is dark (underexposed). Too much, and details get blown out (overexposed). The goal is to get the balance just right — so the image holds both shadow and highlight detail.
But your eyes adjust in real-time. You walk into a dark room? Your pupils dilate. You step into the sun? They shrink. Cameras aren’t that clever — they need you to tell them what kind of light they’re dealing with.
So if you’ve ever looked at your screen and thought, “Why is this photo so bright?” or “Why can’t I see anything in the shadows?” — it all comes back to exposure.
And the three things that control it?
Let me introduce you to the Exposure Triangle.
1.2 Meet the Exposure Triangle
Exposure is controlled by three camera settings:
Aperture (how wide the lens opens)
Shutter Speed (how long the sensor is exposed)
ISO (how sensitive your camera is to light)
These three form the Exposure Triangle. Adjusting any one of them changes how bright or dark your image is — but there's more: they all affect one another.
Think of it like baking.
You want a perfectly moist cake. Add more sugar? Great — but now you need to balance with more flour or eggs. Otherwise, it’s off.
Same with exposure.
Brighten one setting? You may need to darken another to maintain balance.
You don’t memorize perfect settings.
You balance them based on your scene and your intent.
Let’s break each one down.
1.3 ISO – Your Camera’s Light Sensitivity
ISO controls how sensitive your camera’s sensor is to light.
Low ISO (100-800): Less sensitive, cleaner image, less noise
High ISO (1600-6400+): More sensitive, but grainy and noisy
It’s kinda like turning up the volume on a quiet song. You hear more — but you also start hearing background fuzz.
In bright light, you want the lowest ISO possible.
In dim light (a candlelit dinner, golden hour under tree cover, etc.), you’ll need to raise it. That’s okay — but just know the higher you go, the more digital noise you introduce.
Pro Tip: ISO doesn’t create light — it amplifies what’s already there. So don’t crank it unless you have to.
Typical ISO Settings:
Sunny day, or direct light: ISO 100
Cloudy shade: ISO 400
Indoor natural light: ISO 800–1600
Dark churches or dim light: ISO 3200+
1.4 Shutter Speed – Freezing or Showing Motion
Shutter speed is how long the camera’s shutter stays open to let in light.
Fast shutter (e.g. 1/1000s): Freezes motion
Slow shutter (e.g. 1/10s): Shows motion blur
It’s kinda like blinking — a quick blink (fast shutter) lets in less light but freezes what you see. A slow blink (slow shutter) lets in more light but might blur fast-moving objects.
Examples:
Freezing an action shot: 1/1000s
Portrait in soft light: 1/200s
Motion blur of waves: 1/4s
Light trails at night: 5+ seconds
Real-world tip: Shutter speed also determines whether you’ll get camera shake when hand-holding your camera. If it’s too slow, your photos will come out blurry — not because the subject moved, but because you did.
To reduce motion blur, use the reciprocal rule for a safe minimum shutter speed for handheld photography. The reciprocal rule states that your shutter speed should always be at least your lens' focal length.
35mm lens, shoot at 1/40s or faster.
100mm lens, shoot at 1/100s or faster.
1.5 Aperture – Depth, Light, and Blur
Aperture is the size of the opening in your lens. It’s measured in f-stops (like f/1.8, f/4, f/11).
Wide aperture (e.g. f/1.4): More light, shallow depth of field (blurry background)
Narrow aperture (e.g. f/11): Less light, more in focus
It’s kinda like your eye’s pupil. In darkness, it opens wide. In bright light, it constricts. Aperture does the same.
Here’s the part that trips people up: Lower f-number = bigger opening.
Yep, f/1.4 is bigger than f/8. (It’s backwards math. Don’t fight it.)
Artistic impact: Aperture is your storytelling tool.
Want soft, creamy backgrounds that make your subject pop? Use f/1.8 or f/2.2.
Want the whole landscape sharp? Go f/8 or f/11.
Examples:
Couple portrait: f/1.4
Group photo: f/4
Detail macro shot: f/5.6
Mountain landscape: f/11+
1.6 Balancing the Triangle
Remember — you’re not just adjusting settings. You’re making creative decisions.
Let’s say you’re photographing a portrait in open shade. You want:
Blurry background = wide aperture (f/2.0)
Clean image = low ISO (ISO 100)
What’s left? Shutter speed has to adjust to balance the light.
But what if that makes the shutter speed too slow to handhold?
Then maybe you raise the ISO to 400 so you can speed up the shutter. Trade-offs.
Here’s the Triangle Mindset:
If you want more light from one setting, you need to take away light from another.
You can get the same exposure different ways, but each combo creates a different look.
1.7 Metering: How Your Camera Judges Exposure
When you half-press the shutter, your camera tries to figure out the exposure. It shows a meter like this in the viewfinder:
-3 -2 -1 0 +1 +2 +3
“0” = balanced exposure (according to your camera)
“-2” = underexposed
“+2” = overexposed
But here’s the deal: your camera doesn’t understand your subject. It’s just reading light and aiming for “middle gray.” If you point it at a white dress, it might underexpose. If you point it at a black tux, it might overexpose.
That’s why you have to override it sometimes.
Especially in natural light with tricky shadows and backlight.
1.8 Common Exposure Mistakes
Mistake: Shooting in Auto and wondering why every photo looks different
Quick fix: Switch to Manual mode (or Aperture Priority) to control settings consistently.
👉 (See 1.2 Exposure Triangle for clarity.)
Mistake: Ignoring shutter speed, resulting in blurry images
Quick fix: Follow the reciprocal rule—your shutter speed should be at least your focal length (e.g., 50mm lens → shoot at 1/50s or faster).
👉 (Review 1.4 Shutter Speed for details.)
Mistake: Cranking ISO too high when aperture could’ve helped
Quick fix: Open up your aperture first (lower f-number = more light). Adjust ISO as a last step.
👉 (Refresh with 1.3 ISO and 1.5 Aperture.)
Mistake: Overexposing highlights you can’t recover
Quick fix: Expose for the brightest area first (like skies). You can always brighten shadows later.
👉 (Check 1.7 Metering for guidance.)
Mistake: Trusting the screen instead of checking your histogram
Quick fix: Always double-check exposure using the histogram—screens can mislead you.
👉 (More on Histograms!)
1.9 Your First Exposure Walk (Mini Assignment)
Here’s how you internalize this: go out and take 3 versions of the same photo.
Keep shutter + ISO the same, change only aperture
Keep aperture + ISO the same, change only shutter
Keep aperture + shutter the same, change only ISO
Then review the photos and ask:
What changed?
What stayed the same?
Which one feels best?
Optional: import into Lightroom and look at the histogram + metadata.
1.10 Recap: Exposure Is the Creative Foundation
Exposure is more than brightness — it’s creative control.
You now understand:
What exposure is and why it matters
How ISO, aperture, and shutter speed work
How to balance settings instead of guessing
Why light is a language, and exposure is your first word in it
Next up: we’ll dive deeper into ISO — the most misunderstood (and abused) part of the triangle.
Btw its not just about brightness. It’s about intention.
Work One on One With James
