I've been following several posts that either lament the difficulty of teaching or learning exposure or which have tried to explain how things work. Some of these efforts are really good and, in fact, really elegant. I mean no malice toward them here.

But as I have written in another post, I have had an experience recently which significantly impacted my thinking around this topic. It really encouraged me around the ability of people, even kids, to learn how exposure works, and it made me carefully examine how exposure is usually taught. I expressed my most current thinking about this in that other post, but because it is buried deeply in the discussion there, thought I'd start a new one here. So here goes...

In my experience, learning exposure is a mess for primarily two reasons:

1. We make it too complicated when teaching it. (Makes me wonder if we really understand it.)
2. We have no patience. Most of us on this forum have been at this for 30 years or more. But we expect newcomers to get it on the first try.

f/ stop (note the forward slash) is a term with a very specific meaning. For instance, f/5.6 is actually a number calculated by dividing the focal length of that lens by an exposure ratio of 5.6. The result is a number which is the diameter of the controlling aperture of the lens..for instance for a 100mm lens, f/11 represents an aperture diameter of 100mm/11=9.09mm.

f/22 for that same lens represents an aperture diameter of 100mm/22=4.045mm.

Now it turns out that the area of that 9.09mm aperture is exactly 4 times the area of the area of the 4.045mm aperture. You can do the arithmetic. Area of a circle is pi X r X r.

So the larger opening lets in 4 times the amount of light. 2 stops = 4 times the light, 1 stop = 2 times the light. There is no mystery. The arithmetic is not even complicated. We need to stop making it so.

Similarly, a shutter open time that is twice as long also lets in twice as much light. Half as long lets in half as much light. Period. Nothing more than that.

Both of these methods control how much light falls on a piece of film or on a sensor. They can be used equally to control exposure. And each of them also can potentially affect our images in other ways. We'll talk about that separately in a different lesson.

We need to stop making it so complicated.

It's just not.

I've been following several posts that either lament the difficulty of teaching or learning exposure or which have tried to explain how things work. Some of these efforts are really good and, in fact, really elegant. I mean no malice toward them here.

But as I have written in another post, I have had an experience recently which significantly impacted my thinking around this topic. It really encouraged me around the ability of people, even kids, to learn how exposure works, and it made me carefully examine how exposure is usually taught. I expressed my most current thinking about this in that other post, but because it is buried deeply in the discussion there, thought I'd start a new one here. So here goes...

In my experience, learning exposure is a mess for primarily two reasons:

1. We make it too complicated when teaching it. (Makes me wonder if we really understand it.)
2. We have no patience. Most of us on this forum have been at this for 30 years or more. But we expect newcomers to get it on the first try.

f/ stop (note the forward slash) is a term with a very specific meaning. For instance, f/5.6 is actually a number calculated by dividing the focal length of that lens by an exposure ratio of 5.6. The result is a number which is the diameter of the controlling aperture of the lens..for instance for a 100mm lens, f/11 represents an aperture diameter of 100mm/11=9.09mm.

f/22 for that same lens represents an aperture diameter of 100mm/22=4.045mm.

Now it turns out that the area of that 9.09mm aperture is exactly 4 times the area of the area of the 4.045mm aperture. You can do the arithmetic. Area of a circle is pi X r X r.

So the larger opening lets in 4 times the amount of light. 2 stops = 4 times the light, 1 stop = 2 times the light. There is no mystery. The arithmetic is not even complicated. We need to stop making it so.

Similarly, a shutter open time that is twice as long also lets in twice as much light. Half as long lets in half as much light. Period. Nothing more than that.

Both of these methods control how much light falls on a piece of film or on a sensor. They can be used equally to control exposure. And each of them also can potentially affect our images in other ways. We'll talk about that separately in a different lesson.

We need to stop making it so complicated.

It's just not.

I've been following several posts that either lament the difficulty of teaching or learning exposure or which have tried to explain how things work. Some of these efforts are really good and, in fact, really elegant. I mean no malice toward them here.

But as I have written in another post, I have had an experience recently which significantly impacted my thinking around this topic. It really encouraged me around the ability of people, even kids, to learn how exposure works, and it made me carefully examine how exposure is usually taught. I expressed my most current thinking about this in that other post, but because it is buried deeply in the discussion there, thought I'd start a new one here. So here goes...

In my experience, learning exposure is a mess for primarily two reasons:

1. We make it too complicated when teaching it. (Makes me wonder if we really understand it.)
2. We have no patience. Most of us on this forum have been at this for 30 years or more. But we expect newcomers to get it on the first try.

f/ stop (note the forward slash) is a term with a very specific meaning. For instance, f/5.6 is actually a number calculated by dividing the focal length of that lens by an exposure ratio of 5.6. The result is a number which is the diameter of the controlling aperture of the lens..for instance for a 100mm lens, f/11 represents an aperture diameter of 100mm/11=9.09mm.

f/22 for that same lens represents an aperture diameter of 100mm/22=4.045mm.

Now it turns out that the area of that 9.09mm aperture is exactly 4 times the area of the area of the 4.045mm aperture. You can do the arithmetic. Area of a circle is pi X r X r.

So the larger opening lets in 4 times the amount of light. 2 stops = 4 times the light, 1 stop = 2 times the light. There is no mystery. The arithmetic is not even complicated. We need to stop making it so.

Similarly, a shutter open time that is twice as long also lets in twice as much light. Half as long lets in half as much light. Period. Nothing more than that.

Both of these methods control how much light falls on a piece of film or on a sensor. They can be used equally to control exposure. And each of them also can potentially affect our images in other ways. We'll talk about that separately in a different lesson.

We need to stop making it so complicated.
Up
It's just not.