Beginner Photography Class Day 4: Understanding Exposure

They say the color of your eyes determines your eye’s sensitivity to light. Light colored eyes are more sensitive than dark.

My mom and I have blue eyes. We always wear sunglasses outside. We struggle to see without them. And prolonged exposure to bright light without glasses usually gives us a headache.

My husband, on the other hand, has brown eyes. He should wear sunglasses to protect his eyes. But he rarely feels like he needs them.

Today’s lesson is about combining what we know about aperture, shutter speed, and ISO to gain a better understanding of exposure.

Imagine this…

You’re standing inside a room looking out a window. The window is your camera.

To change the amount of light you see in the room you have several choices. You can make the window bigger or smaller to light the room (your aperture). You could leave the shutters open longer or close them sooner (shutter speed). Or you can consider the color of your eyes, knowing that blue eyes are more sensitive to light than brown (ISO).

This example is a bit over-simplified. But hopefully you get the idea.

Your aperture, shutter speed, and ISO work together to give you a good exposure. In Manual Mode (which I never suggest you shoot in as a beginner), you can change these one at a time to see their effect. In Program Mode, which is what I recommend you shoot in 90% of the time, your camera will (most likely) only allow you to change your ISO.

Why? Because Program Mode is like full-auto. Ninety percent of the time, you’ll want your camera to make these decisions for you. In the other 10%, when you want to override your camera’s decisions, you’ll take your camera out of Auto or Program mode and shoot on something else.

Aperture Priority Mode will let you adjust your aperture while the camera decides your shutter speed. Shutter Priority will let you adjust your shutter while the camera decides your aperture. And Manual Mode gives you 100% creative control.

Again, I recommend you set your camera on Program Mode with Auto ISO and leave it there.

Here’s today’s video lesson on how all these things work together:


The exposure triangle is a careful balance between the aperture, shutter speed, and ISO. Understanding the relationship between the three can be easy, but you’ve got to practice.

To help you visualize what effect changing one might have on the others, I found this website that lets you play around with camera settings without leaving your chair.

Thank you for participating in this mini-series, and I truly hope that it helped you gain a better understanding of how your camera works and how learning about its functions can improve the quality of your photographs.

Your success is our success. Great photographers are not born. They’re self-made.

Good luck!

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