I’ve been shooting in the comfort of Aperture priority mode for the past three years and now I think it’s time to graduate to Manual. It can’t be that hard can it? Like driving a stick shift, right?

For the past few days, I’ve been studying up on the more technical basics of photography. Exposure. Trying to wrap my head around it all and today I feel that my eyes have been opened. Learning is indeed a lifelong process and it’s no different with photography.

I will try to explain to you the basics of exposure as simply as possible. Today’s article will focus on aperture and shutter speed.

Aperture controls the area of the opening in the lens which lets the light through.
Shutter Speed controls the length of time the sensor (or film) is exposed to the light.

Pretty basic isn’t it? Now, understanding how those two work together to achieve the proper exposure gets a bit more “involved”.

If you want a “Tedious Explanation of the f-stop“go right ahead and satiate your appetite. I did. But for those of you who aren’t so inclined to do so, I’ll try my best to explain it in my own words.

A combination of aperture (otherwise referred to as the f-stop) and shutter speed will determine your exposure. Fiddling around with both will help you achieve the right balance of light that you need to properly expose your subject. If you want a lot of light, you can make your opening bigger or keep the shutter open for a longer time and finding the balance between the two will help you find the correct exposure.

Stops

When talking about exposure, you need to have an understanding of the term “stop” and how it’s used. For example, a shutter speed of 1/30s is a full stop away from 1/60s. This simply means that the relationship between stops is either doubled or halved, depending on if you’re going up or down. Just keep this in mind while reading the next sections.

Shutter Speed

Shutter speed is measured in seconds or fractions of a second. A full stop is either half or double that of the previous or next stop.

The sequence, in seconds is as follows:
4 - 2 - 1 - 1/2 - 1/4 - 1/8 - 1/15 - 1/30 - 1/60 - 1/125 - 1/250 - 1/500 - 1/1000 etc…

It’s pretty clear that half of 4 is 2 and half of 1/30 is 1/60. (I know 1/60 isn’t exactly half of 1/125 but it’s close enough.) This means that if your shutter is open for 4 seconds, that’s going to let in double the light than if it was open for only 2 seconds. Any questions so far? Let’s move on.

Aperture

Aperture size is referred to as f-stop values, which is a ratio between the diameter of the opening and the focal length of the lens. Because it’s a ratio, the values seem to go backwards with respect to size. An f-stop of 1.4 is a large opening while an f-stop of 22 is a small opening. Therefore, f/1.4 would allow much more light through compared to f/22.  See this article on Aperture with photos of the lens opening.

Values between full stops:
1.4 - 2.0 - 2.8 - 4 - 5.6 - 8 - 11 - 16 - 22

Yes, clearly 2.0 is not double that of 1.4 nor is 5.6 half of 8. That’s because these are ratios and the doubling or halving actually refers to the area of the opening. For simplicity’s sake, I’ll leave it at that. If you want more info, again, read here. The main concept to remember is that, for example, the area of the opening at f/2.0 is double the size compared to the area at f/2.8. That means, at f/2.0, double the light is entering than compared to at f/2.8.

Whew! That was a mouthful!

Now, there are several combinations of f-stop and shutter speeds that will give you the same exposure, or light coming in, since we can adjust it by stops.

For example, if you shoot at an aperture of f/2.8 and shutter speed of 1/500s, that will give you the same exposure as shooting at an aperture of f/4 and shutter speed of 1/250s. The site I linked to earlier, here, has a great printable rotary exposure wheel available for download that might come in handy. You can find it near the bottom of the page.

Here is a series of shots where I adjusted the aperture and the shutter speeds by one full stop and you’ll notice the exposure is very similar in all the images. When I increase the f-stop by one stop, I decrease the shutter speed by one stop. The focal length was set at 50mm for all the images.

The only thing you’ll notice is the depth-of-field has changed, which we will look at in a separate article.

So there you have it. The very basics of aperture and shutter speed. Please, do let me know if you have any questions or comments. Now we just have to throw in ISO and exposure compensation into the mix! But we’ll save that for another time.

Laura is a Vancouver portrait photographer. Visit Dolce Life Photography.