What Does Exposure Mean In Photography?

In photography, exposure is the amount of light that reaches the camera sensor. The amount of light that reaches the sensor is controlled by how long the sensor is exposed to light by the shutter and the amount of light let through the opening in the lens, which is controlled by the aperture. These two factors, combined with the sensitivity of the sensor, which is the ISO, create an exposure.

Okay, so that is exposure. Exposure is a combination of three fundamental settings in the camera, aperture, shutter and ISO.

These three things combine to give you an exposure whenever you take a photo. I'm going to talk about aperture, shutter, and ISO in their own rights in future episodes.

So now I'm just going to stick with exposure and explain a few things about exposure.

Hi, everybody. Welcome to Episode 21 of the Photography Explained podcast. In this episode, what does exposure mean in photography?

I'm your host, Rick, and each week I will try to explain one photographic thing to you in plain English in less than 10 minutes without the irrelevant details. My aim is to explain things in just enough detail to help us with our photography and no more. That's enough detail for me, and it should be for you.

Of course, if you want more detail, there are plenty of places to go to on the internet. But hopefully, I will give you just what you need, and no more.

You can listen to the episode here

Or you can read on - it’s entirely up you!

1 – What is exposure?

We've covered that.

2 - What is an underexposed photograph?

Basically, an underexposed photograph is one where not enough light has reached the sensor, and it means that the photograph is too dark.

Now the photo could be underexposed because the metering was incorrect and the shutter speed was too fast (not slow as I said in the podcast), and it didn't let enough light in.

Or because the aperture was too small, as in it didn't let in enough light.

Or the ISO was wrong.

Now I normally trip myself up by explaining this so I'm quite pleased with this (apart from the major error I have just noticed)

3 – What is an overexposed image?

An overexposed image is too bright. With an overexposed image, too much light has reached the sensor. Now how can that happen?

If the shutter speed is too long, or the aperture is too large, or the ISO is too high (I'll get back to that because there is a point that is incorrect), then you will produce an image that is too light.

3 What is a correctly exposed image?

The simplest way I can describe a correctly exposed image is that the photograph is pretty much representing what you saw when you were looking at what you were photographing.

Now our eyes and our vision are remarkable. We can record a huge amount, and a huge range of lights and darks, more than any camera can in one shot.

And that's a fact. So when you're taking a photo, trying to get a correct exposure, you are starting off from a weak position because the camera cannot recreate what you can see.

One day this will happen and there are ways around it. But that is a basic fact. The human eye is remarkable. The human brain is remarkable. And despite what all these people say about technology, there's nothing better than the human brain yet.

Might be a bit controversial here. And I might not include my brain in that but yeah, it's impossible.

But a correctly exposed photograph is one that looks correct. It has the correct amount of highlights and shadows and all the bits in between.

4 Shadows

Shadows? Do I need to explain that? That's the dark bits.

5 Highlights

The light bits at the opposite end of the scale.

6 Everything else in between.

So I'll say it again because it's important. A correctly exposed image has the right amount of light, the right amount of brightness, the darkness of the shadows, the highlights and all the bits in between. How do you know this? Well, there is one clever way of finding this out.

I just realised my numberings all wrong here. There is no 6!

7 Histogram.

What's a histogram? A histogram is a visual representation of the light in a photo in a scale going from dark on the left or sorry, black on the left to white on the right. And in a perfect histogram, well I can't describe this in words, you will have to go to Lightroom or check on the internet - check with other people, somebody else will have done this one.

A histogram has a scale from 1 to 255. 1 is black 255 is white. And the scale goes from one end to the other. Again, if we were starting again, with photography, would we come up with this? Probably not.

But there is a point to a histogram. I'm not a big user of a histogram, I have to say, but I need to explain that in another episode.

But you can see the histogram on the back of your camera, or in Lightroom or other processing software. And that is a visual representation of the range of brightness in a photo.

Yes, it is a visual representation of your exposure. And whilst I'm not a big user of it, I understand this and I would highly recommend that you understand the histogram, which I'm going to add to my episode list when I finished recording this episode.

8 How do you get an exposure?

How do you get an exposure, I hear you say? Somebody will say so at some point when they finally ask me a question.

There are different ways of getting an exposure, depending on the camera mode that you use.

9 Auto exposure.

I've got to get used to this numbering system. I'll explain why in a future episode. It's a brilliant idea though.

Auto exposure is where the camera sets the aperture and the shutter speed. And I do believe the ISO in certain automatic modes.

10 Semi-automatic exposure

You set the ISO and then say the aperture and the camera selects the shutter speed.

That's what I do, by the way (for all my commercial architectural and construction photography work).

11 Manual exposure.

These are all different modes on DSLRs by the way. DSLRs and other more advanced cameras, shall we say?

With manual exposure you set everything.

Even though you're setting everything you are still doing what the camera tells you to. So when people say you must take all your photos in manual, take that with a large pinch of salt because you can use manual mode and just do what the camera tells you.

And this is not that different, say from using other modes.

Post-episode note – you should learn how to use manual mode so you properly understand the exposure triangle. But this does not then become a mandatory millstone around our necks.

12 Creative Exposure

Creative exposure is where you take the camera's recommended settings and you do something completely different in a creative way.

Which I do all the time.

13 Lightroom

Get the exposure right in camera – this is the important fundamental thing.

Guess what though? In Lightroom, you've got huge amounts of adjustment of the exposure, of the shadows, highlights, blacks and whites.

So is it really important to get the exposure right in camera?

Yes, it is.

Because you need to start with the correct starting point. So let's get things right in camera guys.

Okay, that's exposure done. What's next?

Next is aperture. I'm going to talk about aperture for 10 minutes. Not a problem. Okay. What Is Aperture In Photography?

Thank you. I'd like to thank you for listening and I hope you enjoyed this episode. I hope it all made sense. If it did, please leave a nice review and rating wherever you get your podcast from. And please subscribe so you don't miss an episode.

If you could also tell everyone you know about my podcast that would be even better. And you get a big thank you from me. You can also check out my website Rick McEvoy Photography where you can find out all about me and my architectural and construction photography work, as well as my blog where you can learn a lot more about photography. There's lots on there, it's all good stuff.

A quick plug for me and what I do.

Well, why not? If I can't plug myself on my podcast, where can I?

You have found this podcast, so why not check out my splendid website, where I write blog posts about my photographs of buildings and other good stuff. On my courses page, you will find my course, How to Become A Real Estate Photographer.

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Okay, this episode was brought to you by the power of still waiting for somebody to support the show. So is back to Yorkshire tea bought this morning at 10 past seven by me from the local Co-Op. I had to go out (in my pyjamas) in the pouring rain to get some milk and we only had two tea bags.

I'm definitely waffling now.

What’s next? In the next Photography Explained Podcast - Episode 22 - Merry Christmas, followed by Episode 23 - What Is Aperture In Photography?

I've been Rick McEvoy. Thanks again for listening and giving me 10 minutes of your valuable time. I'll see you in the next episode.

Cheers from me, Rick