5 Jargon Terms BUSTED – The Great Exposure Debate

Jargon Busting Photography!

Today we're going to demystify some jargon terms so that they won't hold you hack in your learning.

In particular we're going to have a look at one of the most fudged and confusing terms in photography and the ramifications of that confusion to all the other terms as we go.

We all hate jargon, and we don't want it to be a bar to your learning. That's why we put together this article.

This is part one of a jargon busting extravaganza!

The good news is, there's no nuclear physics behind any of the terms. It's actually not that difficult. You won't get a photographer saying "the energy released by nuclear fission or fusion is equivalent to the mass loss multiplied by the speed of light squared" - (think Einstein). We're not that bad.

If you scroll down there's a video to accompany this article, but you'll learn far more if you both read and watch. Scientific studies have been done on this - really! We're not going to give you the jargon term for that, but there is one.

5 Essential Photo Jargon Terms Demystified

Bonus Term: The word "Photography"

This term is itself jargon:

Photo - meaning light

Graph - Writing or painting

We are "painting with light". I've added this one in solely because if you understand that light is the most important element of photography you'll go a long way.

1 Exposure

Historically exposure referred to the amount of light to which the glass plate was "exposed" while the photograph was being taken. It was "exposing" the glass plate to light that created the image.

Today exposure can means either:

The amount of light that reaches the camera's sensor i.e. the amount of light the sensor is "exposed" to when the image is taken. This is is sometimes called "luminous exposure" as a technical concept with a horribly mathsy equation.


One of two colloquial terms:

The brightness of the final image 


The final product - the image file taking into account all it's components and component settings

Arguing whether one of these definitions is technically right or not isn't really the point because all these meanings are ingrained in photography language. When we talk of exposure we could mean any single one of them! Bonkers right?!

Evolution of Technology and Terms

All 3 concepts of exposure evolved out of the historic act of "exposing" a plate to the light creating an image. Arguably when the concept of exposure was first coined all 3 definitions meant the same thing. The exposure to the light was a direct cause of the image brightness, and a direct cause of the final product. 

Then the massive evolution of technology and language happened and they all mean something different. It's a bit like using the term "dialing a number" today using your mobile or cell 'phone.

Brightness Exposure

When learning it's helpful to have the "image brightness" definition in your head:

Think of:

An over exposed image being too bright

An under exposed image being too dark

See the image below.

Staithes, Under-Exposed


Staithes, Correctly Exposed


Staithes, Over-Exposed



ISO used to relate to the sensitivity of the film used which was being "exposed" to the light. An ISO 100 film was not very sensitive to light whereas an ISO 800 film was very sensitive to light. With an ISO 800 film you could make a "correct exposure" with less light.

Today ISO is the amount by which the digital signal from the sensor is amplified to get to the correct image brightness. We still use the old ISO numbers system, but rather than referring to the sensitivity of the film we are looking at perceived sensitivity by way of digital amplification. The two systems work very differently, but to the same end - an image of the correct brightness. At ISO 800 you are using more amplification than ISO 100 so you can get to the right brightness with less light.

ISO and Exposure

Technically ISO isn't part of technical or luminous exposure because that's about the "the amount of light hitting the sensor" when an image is taken.

ISO does still however affect the brightness of the final image - the result. The amount of light hitting the sensor (technical luminous exposure) plus ISO is what determines whether the final image will be the correct brightness. 

luminous exposure + ISO = image brightness

Understanding Exposure

Understanding exposure and it's components is one of the fundamental skills of a photographer. When you become skilled you can manipulate all the components of exposure to some fantastic creative effects like those stunning blurred backgrounds, motion blur and freezing fast action. If you'd like to take control of your photography and learn all about camera craft composition and kit we have a fabulous online course, Photography Fundamentals.

Ready to move to the next level?

Online Beginners Course!

Only £97!

3 Exposure Triangle

Below is the exposure triangle.

The Exposure Triangle is a method of understanding how the main settings on a camera relate to each other, to get an image of the correct brightness. So exposure here is really referring to image brightness.

It's made up of 3 components shutter speed, aperture and ISO.

Shutter speed and aperture determine the amount of light that hits the sensor - technical exposure / luminous exposure. We'll look at what these settings mean in part 2 of this video.

ISO appears because it contributes to image brightness even though it's not technically part of luminous exposure. 

The fact the components fit into different definitions of exposure is confusing, but remember:

Luminous exposure + ISO = brightness exposure.

The exposure triangle is in effect a settings triangle. All 3 settings on this triangle affect whether the final image is of the correct brightness - think of it this way and lets not argue about what technically makes an exposure.

4 Metering

Your camera's light metering system looks at or "meters" the amount of light available to help determine the correct exposure. 

Your camera's Exposure Value meter will warn you whether your image will be under of over exposed (brightness). In doing so it will look at all 3 exposure triangle settings. 

5 Noise

Digital noise is the "grainy effect" you can get on photos - see the inlay shot. It looks similar to film grain, but has a very different cause.

When light hits your cameras sensor (luminous exposure), it is converted into a digital signal. If the signal is poor quality that will show in the final image as noise.

So if you put in low light levels you get a poor quality signal which results in digital noise. If you then amplify that signal with ISO you also amplify the noise.

Here's the video we teased...

Would you like to really master the photography basics?

We've just given you lots of photography terms but if you really want to learn how to use them all in practice you might like to check out our online beginners photography course: Photography FUNdamentals.

We have a whole module dedicated to camera craft which includes chunks on shutter speed, aperture, ISO, and the cool effects they can give you. We'll show you how to master your camera's modes so that for every scenario you'll know the best mode to pick and how to key the right exposure triangle settings. We also cover composition and kit.

It’s an online photography course with a difference. We try and make photography for beginners fun and easy to understand. You’ll find easy to follow graphics, cheat sheets, exercises an online learning community and so much more.

If you would like more information and help with photography for beginners, please click here to buy the course now.

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