Understanding ISO: What You Need to Know

Your beginner-friendly guide to mastering one of the most misunderstood camera settings.

Let me take you back 20 years. I had just started my photography journey, bright-eyed, full of excitement—and absolutely terrified of ISO. I would never, ever let that number creep above 400. “Too noisy,” I thought. Grainy photos? No thanks! I'd rather miss the shot than risk that dreadful digital snow.

Fast forward to today, and I regularly shoot at ISO 3200 or higher—and not just in emergencies. Why? Because modern cameras are so much better at handling high ISO. Once you understand how it works (and how to use it), ISO becomes one of your most powerful creative tools. So let’s break it down, in simple terms, with some easy-to-apply tips and real-life examples.

What Is ISO, Anyway?

ISO is one of the three pillars of exposure, along with shutter speed and aperture. In plain English, ISO controls how sensitive your camera’s sensor is to light.

• Low ISO (e.g. 100 or 200) = less sensitive = cleaner images, but you’ll need more light.

• High ISO (e.g. 1600, 3200, even 6400!) = more sensitive = better for low-light, but potentially more “noise” (grainy texture).

Think of ISO like the volume knob on a speaker. If the music is too quiet (aka, not enough light), you can crank up the volume (ISO), but you might hear a bit of static (noise).

How ISO Works with the Other Settings

ISO doesn’t work alone—it’s part of the exposure triangle. Here's how they all play together:

• If you’re shooting in bright sunlight, keep ISO low—your shutter and aperture will do most of the work.

• If it’s getting darker, and you can’t slow your shutter (because your subject is moving) or open your aperture (because you’ve maxed it out), then ISO is your best friend.

👉 TIP: Start with ISO 100 or 200 in daylight. Bump it up gradually as light fades. Don’t be afraid to experiment—your camera can probably handle more than you think.

When You’ll Want to Use High ISO

You don’t need to be afraid of high ISO anymore (I promise). Here are some everyday situations when it’s the right tool for the job:

🌙 1. Low Light or Night Photography

Shooting under streetlights, at events, or after sunset? High ISO helps you keep your shutter speed fast enough to avoid blur.

🐦 2. Wildlife or Action Shots

When that bird suddenly takes flight, you need a quick shutter speed. Higher ISO lets you freeze motion without underexposing.

🏠 3. Indoor Photography

If you’re inside with natural light or soft lamps, raising your ISO keeps the photo sharp even without a flash.

📸 4. Handheld Shooting

No tripod? No problem. A higher ISO means you can use a faster shutter and avoid camera shake.

An ISO of 4000 was used to allow for a high F number in dark conditions to create a starburst effect

This photo was taken in a dark rainforest setting so an ISO of 5000 helped to balance the light.

To freeze the movement of this fast flying bird I needed a high shutter speed and ISO 10000

But... What About Noise?

Ah yes, the dreaded noise. But here’s the thing: noise isn’t the enemy it used to be.

Modern cameras (even entry-level DSLRs and mirrorless) do a fantastic job of managing noise. And even when there is a bit of grain, it's often barely noticeable—especially if your exposure is correct and you’re not over-editing later.

My Advice?

• Don’t pixel-peep—view your photos at normal size, not zoomed in 500%.

• A sharp, well-lit photo with a little grain is always better than a blurry photo with perfect ISO.

• You can reduce noise in editing software like Lightroom (which I cover in my editing course too!).

A Quick ISO Reference Guide

Here’s a handy cheat sheet for you:

Lighting Condition	Suggested ISO
Bright Sunlight	ISO 100–200
Cloudy/Overcast	ISO 400–800
Indoors (daylight)	ISO 800–1600
Indoors (evening/lamp)	ISO 1600–3200
Night / Astro	ISO 3200–6400+

💡 Tip: Every camera is different. Find your ISO sweet spot by testing in low light and seeing where noise becomes a problem for your specific model.

ISO in Auto Mode vs Manual Mode

If you're using Auto mode or one of the semi-automatic modes like Aperture Priority, your camera might change the ISO for you. That’s not a bad thing—especially when you're getting started.

But if you want full control over how your photos look (and I think you do), start experimenting with Manual Mode or Manual ISO settings.

👉 Need help getting your head around all these buttons and settings? My Get To Know Your Camera course is designed for exactly that. We cover ISO, shutter speed, aperture—and how to actually use them in the real world. And it’s a lot more fun than reading your camera manual!

Final Thoughts: Don't Be Scared of ISO

If there’s one thing I want you to take away from this post, it’s this:

🎯 ISO is not the enemy.

It’s just a tool—one of many in your creative kit. Learning when and how to use it will give you more freedom, more flexibility, and way more confidence with your camera.

Back when I was just starting out, I limited myself because I didn’t understand ISO. Don’t make the same mistake I did. Get comfortable with it, play with it, push it a little. You might be surprised how far your camera can go.

Ready to Take the Next Step?

If you’re still feeling a little unsure about ISO (or any other camera setting), my Get To Know Your Camera course might be just what you need. It’s a hands-on, supportive way to build your skills, ask questions, and start shooting with confidence. I’ll be there to guide you every step of the way—and yes, we’ll absolutely conquer ISO together.