The Exposure Triangle

Before you start improving your photography it is absolutely essential that you get it clear in your mind what ‘exposure’ is and what 3 factors in your camera affect exposure.

The exposure triangle is something many amateur photographers have heard of but few understand fully. Be sure to read this page a few times until you are clear on all of the points made. The exposure triangle will form the heart of all of your photography and having the ability to manipulate the triangle will be the thing that really helps you move your photography to the next level.

Before we talk about the 3 elements of the triangle together let us first remind ourselves what each individual piece of the triangle is.

The Exposure Triangle

The Exposure Triangle

1. Aperture

Your camera works by sucking light in through a lens and allowing it to hit a sensor in your camera which turns the light into a digital image. The aperture is simply a hole in your lens that opens (to let the light hit your cameras sensor) then closes again when the image is exposed correctly. The aperture is made up of a number of interlocking diaphragm blades that open to allow the light into the camera.

The size of the hole in the lens is measured by what is known as the f-stop or f-number. The smaller the number (e.g. f2.8), the bigger the hole in the middle and therefore the more light is allowed into the camera. Therefore a setting of f2.8 lets more light into the lens that f16. Therefore we can control how much light gets into the camera’s sensor by adjusting the aperture of the lens.

2. Shutter Speed

The second element in the exposure triangle is the shutter speed. This is simply the amount of time that we keep the shutter open. Along with the size of the hole (aperture) this also allows us to control how much light is allowed to hit the camera’s sensor. Naturally it follows that the longer the shutter speed the more light hits the sensor.

Shutter speeds are measured in fractions of seconds e.g. 1/60 of a second or 1/2500 of a second

3. ISO

ISO is the third and final element in the exposure triangle. This element is the sensitivity of the cameras sensor to light. By adjusting this we can make the sensor more sensitive to light. The downside to having a high ISO is that as we increase the sensitivity we lose clarity in our images. Increasing the ISO tends to mean the resulting photographs get more grain/noise.

High ISO Can Cause Grainy Images

High ISO Can Cause Grainy Images

The Exposure Triangle: Summary

Ok so here is a brief summary of how the 3 pieces of the Exposure Triangle affect our photographs:

Aperture: Small f number = big hole in lensĀ  = more light into the camera = Our photo appears brighter

Shutter Speed: Slower shutter speed = more light into the camera = Our photo appears brighter

ISO: Higher number = more sensitivity to light = Our photo appears brighter (but may be grainy)

When we use our camera in automatic mode it essentially assesses each scene and adjusts all three of the above variables to what it thinks are the best proportions in order to take a decent shot.

Most modern digital cameras do a pretty good job of getting the balance right however in order to take spectacular photographs we need to take control of the settings ourselves.

In order to take our photographs from flat, acceptable images to those with real distinction and vibrancy. In order to do this we need to learn how to use some of our cameras other modes. Take a look at these tutorials:

Learning to use Aperture Priority Mode
Learning to useĀ  Shutter Priority Mode
Learning to use Manual Mode

Learning to use ISO

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Thursday Photo Thoughts: Shooting in Manual << Life With Ephram
March 18, 2011 at 1:11 am

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Doug February 7, 2011 at 5:49 am

“The aperture is simply a hole in your lens that opens (to let the light hit your cameras sensor) then closes again when the image is exposed correctly.”

This is half-right, the first part is correct, however the second part describes the function of the shutter.

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