What Have We Learned About Exposure?
Exposure is the amount of light that reaches the camera sensor ( yes, I'm reading this). The amount of light that reaches a camera sensor is controlled by the amount of time the shutter is open (shutter speed), and the amount of light that passes through the opening in the lens aperture.
The third part of the exposure, or the exposure triangle, which I've spoken about before, is the sensitivity of the camera sensor to light, which is determined by the ISO selected.
I've been talking about this in recent episodes. I started off talking about the fundamentals of photography, and then I went on to composition, which was interesting. And after composition, I thought, exposure - that's a pretty important part of photography.
So I'm glad that I'm glad there's a bit of a logic to it. This is a quick recap episode that won't be 10 minutes. Or it might be, you just never know. And at the end of this one, I have got a bit of news which is exciting to me.
Hi, everybody. Welcome to Episode 30 of the Photography Explained podcast. In this episode, what have we learned about exposure? 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 you and me with our photography, and no more.
I'm a professionally qualified photographer based in England with a lifetime of photographic experience, which I share with you on my podcast. That was meant to be the statement about why it is that I'm in a position to be able to teach you about photography stuff.
You can listen to the episode here
Or you can read on - it’s entirely up you!
Okay, hopefully I'll do better on the next one. Anyway, this is a much less scripted episode, which I'm actually looking forward to doing. Some of the last ones have been a bit deep and a bit technical and specific.
I want to have a general waffle really about exposure. So this episode is titled, What have we learned about exposure?
Let's have a little recap on that. I'm getting into my recapping on things now because I've realised that with things that I thought I knew, that I had to do some work on, the recaps certainly helped me remember stuff.
And I hope that they help you too.
So what have I covered on the subject of exposure?
Firstly, the exposure triangle.
This is the combination of the aperture, the shutter, and the ISO to create an exposure for an image. Now the three elements of the exposure triangle are
The aperture.
This is the opening in the camera lens. The wider the aperture, the more light that gets in, the smaller the aperture, the less light that gets in
A wider aperture has a smaller number, a smaller aperture has a larger number.
See when you put it like that it doesn't make any sense at all, does it?
What are the F numbers on an aperture? I don't really understand them and they are not in a logical scale either. So let's not worry about that.
Large aperture small number, small aperture, big number, that's the fundamental point to take out of this.
Obviously, there is a lot more to the aperture than just the size of the opening – this is one for another time. Let's do this nice and gently nice and slowly, nothing too heavy.
Shutter speed.
Now the shutter is something that is made of metal, we think, which is in its normal state is closed. When you press the shutter release button the shutter comes up exposing the sensor to the light coming through the camera lens.
You can change the shutter speed on most cameras.
The faster the shutter speed, the less time the shutter is open, and the less time the sensor is exposed to light.
The longer the shutter speed, the more the sensor is exposed to light.
The third element of the exposure triangle is ISO.
ISO - what does it stand for? Doesn't matter. Don't worry about it. We need to know it relates to the sensitivity of the camera sensor to light.
A low ISO number, say 100 is the ISO that I use. This is known as a low ISO.
I forgot to mention shutter speed and aperture scales out. If you go back to the previous episodes you'll find them covered.
the ISO scale goes up in logical numbers, it goes 100, 200, 400, 800, 1600 - you get the idea.
Making Changes
Each adjustment of the ISO is a full stop of light. Now this is the same for aperture, shutter and ISO, I'll come on to stops in another episode.
But for now, if you go from an aperture of F8 to F5.6, you're opening the aperture, making the opening larger, allowing more light in. This is actually a doubling of the amount of light.
If you change the shutter speed by a stop, you are changing the amount of time the shutter is open. And if you're going in full stops again, this is a halving or doubling of the light that gets through to the sensor.
Same with ISO - ISO 100 to 200 is a doubling of the sensitivity of the sensor.
Now hopefully you can see from this little summary of the episodes to date that these three combine together to give you the exposure of a photograph. So aperture is the size of the opening, letting the light in, shutter speed is the time the shutter is open, and ISO is the sensitivity of the camera sensor to light.
What about film cameras?
I say camera sensor. You can still get film cameras, but I'll be honest with you, I haven't used one in probably 30 years! Is it really 30 years since I've used a film camera? Absolutely shocking!
Next was exposure compensation, which is a quick way of adjusting the exposure to suit the lighting conditions, and how the camera records the light. And also if you want to do something creative, which isn't doing exactly what the camera is telling you to do.
Okay, that was my quick recap on exposure.
So, exposure is the amount of light that reaches the camera sensor – that is my one-line summary.
Okay then so what do I want you to do now?
I want you to play with the exposure triangle and exposure compensation.
Sorry, I missed number one again, I'm always doing that.
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Next episode, we're gonna go back to the camera now - What Are The Different Camera Modes?
It makes sense because I've mentioned them in this episode for the first time. So that's what I'm gonna do next.
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Okay, this episode was brought to you by the power of my stumbling. I forgot to say if you want me to explain something, head over to the new website. Click on the tile which takes you to my email address, to be honest with you, because the forms not working.
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And that's it.
I've been Rick McEvoy. Thanks again for listening to me. Thank you for giving me 10 minutes of your time, and I'll see you on the next episode, which between us I'm going to record right now.
Cheers from Me Rick