In this post, we will be discussing a topic that should be familiar to nearly everyone, but particularly to photographers! And even though you might know a little about it, you might still be astonished at how much you didn’t know!
Of course, we all know that to take a decent photograph, we should find the right light exposure for our photo’s scene. For example, many people use the camera’s flash when it’s dark outside.

So, What is Exposure? And How Can We Get It Right?

Exposure is simply the period of time in which we expose the sensor of our cameras to light.
Light exposure is often dependent on 3 key factors:

1. ISO: The sensor’s sensitivity to light.
2. Shutter Speed: The speed of the camera’s shutter. Also known as exposure time.
3. Aperture: Is the opening that determines the cone angle of the lens.

These three elements, when combined together, form what is known as the Exposure Triangle. According to these three factors or elements, we can increase or decrease the exposure to light.

Caption: Exposure Triangle © Junkiee.Net

Let Me Elaborate…

Let’s say that you’re standing in a room that has a window with shutters.

Caption: Good Morning II by Patrick Ruegheimer

1. Aperture is the size of the window. A bigger window means brighter rooms, and a smaller window means less brightness in the room. Also, bigger causes a lower depth of field (DoF) and vice versa.
2. Shutter speed is the amount of time that the shutters of the window are open. The longer you leave them open, the more light comes in.
   When we take a picture of something that’s moving fast, such as photos in sports photography for example, we will need to adjust our shutter speed such that it’s high enough to capture the moving object or subject perfectly.
3. ISO is how your eyes receive that incoming light towards your eyes. (If you were wearing shades inside the room, the ISO would be lower). Keep in mind that the more we increase the ISO speed, the more we get some noise in our picture.

Therefore, you have 3 options: you could increase the time that the shutters are open (decrease the shutter speed), or increase the size of the window (increase the aperture) or you could takeoff your sunglasses (higher ISO speed).

Finally, to know how if our exposure is OK, check the light meter in your camera.
The (C) should always be in the middle.

Keeping in mind that + sign will give you an overexposed picture while the – sign will give you an underexposed picture.

In Conclusion

These three factors are responsible to get any exposure we desire, be it high or be it low.
But in order to fully understand the exposure triangle and the difference between each of its parts, I recommend taking many photos of one particular subject, and in each picture change something to see how it effects your picture.