Contents
This series will have six parts, each of which might be a substantial read, but are all important to understanding how to use your camera and get it to do the things you want to do.
- Camera Controls - P, A, S, M modes and Autofocus Modes
- Focal Length Choice
- Aperture and Shutter Speed Choice
- Principles of Composition
- Understanding Flash
- Workflow and Post-Processing
Understanding Focal Lengths
Engineers will tell you a lot of jargon about focal lengths. Essentially, it is just the distance over which collimated (parallel) rays of light are brought into focus. This definition really doesn't pertain to photography, however. What we usually associate focal length with, in photography, is magnification. A lens which has a longer focal length allows us to get closer to things that are further away.
Lenses come in two variants - prime lenses and zoom lenses. Prime lenses only allow us to use one focal length, e.g. 50mm. Zoom lenses allow us to use a range of focal lengths, e.g. 16-35mm. We're not going to get into the specifics of comparing prime and zoom lenses here, but we're going to look at how focal lengths can change our magnification. Take a look at the following photos, one at 24mm and the other at 70mm.
Lenses come in two variants - prime lenses and zoom lenses. Prime lenses only allow us to use one focal length, e.g. 50mm. Zoom lenses allow us to use a range of focal lengths, e.g. 16-35mm. We're not going to get into the specifics of comparing prime and zoom lenses here, but we're going to look at how focal lengths can change our magnification. Take a look at the following photos, one at 24mm and the other at 70mm.
We can see that the first picture is much more 'zoomed out' than the second one. Here's the first takeaway point - lenses which are longer allow us to take photos of further away things. For example, if you're looking to take pictures of birds or other small subjects from a distance, you'll need a lens which has a long focal length. On the other hand, if you're looking at taking landscapes where you want to 'take everything in', you'll need a lens which has a lower focal length.
As a general guide, 50mm is a standard focal length, which represents, roughly, what the human eye sees. A slightly wider lens, such as the 35mm or 28mm, is popular in photojournalism because it takes in more of the background than a 50mm and allows the photographer to get a little closer to subjects. Telephoto lenses are lenses we use to get closer to things that are far away. A standard mid-telephoto which professionals love is the 70-200mm. Anything longer than that is often called a super-telephoto, such as lenses that go to 300mm, 400mm and even to 800mm. These are only really used by wildlife, action and aviation photographers.
If you've just purchased your first camera, you'll probably have purchased it along with a kit lens, which is usually an 18-55mm, which is a good place to start as it allows you to go from a pretty wide to slightly long focal length.
Have a play with your lens and see how close and far away from things you can get.
You might have also got a telephoto such as a 55-200mm in your kit. Have a play with that too and see how much further you can see with them.
As a general guide, 50mm is a standard focal length, which represents, roughly, what the human eye sees. A slightly wider lens, such as the 35mm or 28mm, is popular in photojournalism because it takes in more of the background than a 50mm and allows the photographer to get a little closer to subjects. Telephoto lenses are lenses we use to get closer to things that are far away. A standard mid-telephoto which professionals love is the 70-200mm. Anything longer than that is often called a super-telephoto, such as lenses that go to 300mm, 400mm and even to 800mm. These are only really used by wildlife, action and aviation photographers.
If you've just purchased your first camera, you'll probably have purchased it along with a kit lens, which is usually an 18-55mm, which is a good place to start as it allows you to go from a pretty wide to slightly long focal length.
Have a play with your lens and see how close and far away from things you can get.
You might have also got a telephoto such as a 55-200mm in your kit. Have a play with that too and see how much further you can see with them.
Understanding Angle of View
Field of view (or more correctly - angle of view) refers to how wide or narrow you will be able to see. If you've ever looked down a tube (like a pirate), you'd experience what we call tunnel vision, your vision is concentrated into one little particular spot and you have very little peripheral vision. This is known as having a small angle of view. If you now remove the tube and look at the world directly, you can see much more, representing a much wider field of view.
This also applies in photography. The longer the focal length of the lens is, the more severe the tunnel vision is. Even looking at the example above, at 24mm, we are able to see much more of the surroundings than we are at 70mm. We can represent this graphically.
This also applies in photography. The longer the focal length of the lens is, the more severe the tunnel vision is. Even looking at the example above, at 24mm, we are able to see much more of the surroundings than we are at 70mm. We can represent this graphically.
The point of this discussion is, however, to point out a much more important point. Let's say that instead of keeping the same distance away from the subject, we use a longer lens, but move further away from the subject, so that the subject is the same size. This would look something like this, graphically.
You would probably think that the two images will be the same, but they're not. In fact, even though the subject would appear relatively similar, the difference between the two images would be in the background. Have a look at the graphic above, see how the longer lens contains much less background? That's what we call the telephoto compression effect, telephoto lenses (lenses which are longer) compress the background and washes it away.
This is why portrait photographers love their 200mm f/2 and 300mm f/2.8 primes. Longer lenses and larger apertures help to just wash the background away into a blur of nothingness. The larger aperture makes sure that the background is smooth, as you will learn in the next section. The longer focal length will make the background look much more compressed and cleaner. Consider the following examples.
This is why portrait photographers love their 200mm f/2 and 300mm f/2.8 primes. Longer lenses and larger apertures help to just wash the background away into a blur of nothingness. The larger aperture makes sure that the background is smooth, as you will learn in the next section. The longer focal length will make the background look much more compressed and cleaner. Consider the following examples.
Choosing the Right Focal Length
So far we've touched a little bit on the principles of focal length choice. Essentially, the principle determinant in choosing a focal length is how much you want to get in and how far away you are from your subject.
If you're shooting sports, for example, and you're sitting from the sidelines, well you don't really have much choice, do you? You really only have the longer focal lengths to choose from. Perhaps a 70-200mm f/2.8 is a good choice, it's the standard pro telephoto lens. Some sports photographers shooting more faraway sports might want to have a look at the 200-400mm f/4.
If you're shooting landscapes, however, you do have some choice. You can use a ultra-wide angle lens and try to "get it all in" or you might want to go with a more standard to telephoto lens which will allow you to isolate out smaller frames. Of course, it's not all that simple. We just touched on field of view before. Using a wider lens will make the background smaller. So that might be something you have to take into consideration when shooting landscapes, whether you want to blow out the background and isolate your foreground or whether you want all of it in.
If you're shooting architecture and real estate, your only real choice is wide. It makes the spaces more expansive as you are able to get more area into the pictures and it will give you a more impressive view of your buildings.
If you're shooting portraits, it's often good to use around an 85mm lens. One of my favourite portrait lenses is the Nikon 85mm f/1.8G lens, which allows me to stay faraway enough from subjects to get a decent perspective, but not having to stand so far away I'm yelling at them. The problem with shooting portraits with wide angle lenses is that you have to get in so close it distorts perspective and it's not representative of what our eyes see. If you don't stand 30cm in front of someone's face to look at them, then you shouldn't use a lens which requires you to stand 30cm in front of them - the image you produce will, of course, not be natural.
If you're shooting sports, for example, and you're sitting from the sidelines, well you don't really have much choice, do you? You really only have the longer focal lengths to choose from. Perhaps a 70-200mm f/2.8 is a good choice, it's the standard pro telephoto lens. Some sports photographers shooting more faraway sports might want to have a look at the 200-400mm f/4.
If you're shooting landscapes, however, you do have some choice. You can use a ultra-wide angle lens and try to "get it all in" or you might want to go with a more standard to telephoto lens which will allow you to isolate out smaller frames. Of course, it's not all that simple. We just touched on field of view before. Using a wider lens will make the background smaller. So that might be something you have to take into consideration when shooting landscapes, whether you want to blow out the background and isolate your foreground or whether you want all of it in.
If you're shooting architecture and real estate, your only real choice is wide. It makes the spaces more expansive as you are able to get more area into the pictures and it will give you a more impressive view of your buildings.
If you're shooting portraits, it's often good to use around an 85mm lens. One of my favourite portrait lenses is the Nikon 85mm f/1.8G lens, which allows me to stay faraway enough from subjects to get a decent perspective, but not having to stand so far away I'm yelling at them. The problem with shooting portraits with wide angle lenses is that you have to get in so close it distorts perspective and it's not representative of what our eyes see. If you don't stand 30cm in front of someone's face to look at them, then you shouldn't use a lens which requires you to stand 30cm in front of them - the image you produce will, of course, not be natural.
Crop Factors
It's important to understand crop factors. When we refer to focal lengths, we often refer to the standard 35mm film format. This is the traditional film format you would have used if you were shooting photos around 20 years ago.
If you're using a smaller, cheaper DSLR such as the Canon APS-C bodies or Nikon DX bodies, you will need to apply a crop factor to your lens because those cameras have smaller (and cheaper to manufacture) sensors. I call these sensors crop-frame sensors. For example, the Nikon D3000, D5000 and D7000 series (e.g. the D7100) are all DX format. Cameras which have sensors the same size as 35mm film are called FX (for Nikon) or full-frame (every other brand) else.
This is easy to understand. For Nikon DX, multiply the focal length by 1.5. For Canon APS-C, multiply the focal length by 1.6.
This just means that if you're using a 50mm lens on a Nikon DX camera, it will be equivalent to a 50*1.5 = 75mm lens on a full-frame (FX) camera.
ADVANCED: What most people tell you is what I've just told you above, however, it's important to understand that what is actually happening is that you are actually just cropping in on the full-frame image when using the same lens on a crop-frame sensor. You actually do not get the same field of view with a 75mm lens on a DX format as a 50mm lens on an FX format. All you're doing is chopping off the border around the edges.
If you're using a smaller, cheaper DSLR such as the Canon APS-C bodies or Nikon DX bodies, you will need to apply a crop factor to your lens because those cameras have smaller (and cheaper to manufacture) sensors. I call these sensors crop-frame sensors. For example, the Nikon D3000, D5000 and D7000 series (e.g. the D7100) are all DX format. Cameras which have sensors the same size as 35mm film are called FX (for Nikon) or full-frame (every other brand) else.
This is easy to understand. For Nikon DX, multiply the focal length by 1.5. For Canon APS-C, multiply the focal length by 1.6.
This just means that if you're using a 50mm lens on a Nikon DX camera, it will be equivalent to a 50*1.5 = 75mm lens on a full-frame (FX) camera.
ADVANCED: What most people tell you is what I've just told you above, however, it's important to understand that what is actually happening is that you are actually just cropping in on the full-frame image when using the same lens on a crop-frame sensor. You actually do not get the same field of view with a 75mm lens on a DX format as a 50mm lens on an FX format. All you're doing is chopping off the border around the edges.
Primes vs. Zoom Lenses
Prime lenses are lenses where you cannot change the focal length. For example, a 50mm f/1.8 is a prime lens as it has a fixed focal length of 50mm and that cannot be changed.
Zoom lenses are lenses where you can change the focal length within a specific interval. For example, a 24-70mm f/2.8 is a zoom lens as you can select any focal length you want between 24mm and 70mm.
Prime lenses still exist because they tend to be cheaper than equivalent zoom lenses. They are also smaller, lighter and generally produce sharper images. When you start learning about aperture in the next section, prime lenses also have larger apertures (generally) than zoom lenses.
Zoom lenses are convenient, however, they're generally bigger and heavier, as well as more expensive. They have smaller apertures, which means they let in less light than prime lenses, making them worse in low light situations.
I believe zoom lenses are preferred by most people, but prime lenses encourage you to think about your photography more, rather than being lazy and zooming to frame your image. That's my own personal opinion only, however.
Zoom lenses are lenses where you can change the focal length within a specific interval. For example, a 24-70mm f/2.8 is a zoom lens as you can select any focal length you want between 24mm and 70mm.
Prime lenses still exist because they tend to be cheaper than equivalent zoom lenses. They are also smaller, lighter and generally produce sharper images. When you start learning about aperture in the next section, prime lenses also have larger apertures (generally) than zoom lenses.
Zoom lenses are convenient, however, they're generally bigger and heavier, as well as more expensive. They have smaller apertures, which means they let in less light than prime lenses, making them worse in low light situations.
I believe zoom lenses are preferred by most people, but prime lenses encourage you to think about your photography more, rather than being lazy and zooming to frame your image. That's my own personal opinion only, however.
Summary
Focal lengths is a matter of choice, much like anything we do in photography. Unlike many other fields, there's rarely a right or wrong when it comes to taking pictures. If the pictures you take look good to you and you're happy with them, then power to you, keep shooting the way you are and be happy with what you're shooting.
As long as you understand the principles of focal lengths, you can always choose a focal length which will achieve the artistic effect and suit the situation you are trying to shoot. The best way to learn about focal lengths is to try. Instead of just standing in one spot and zooming in or out to get the frame you want, why not try and use a fixed focal length (prime) lens and move around to see the different perspectives you will get.
As long as you understand the principles of focal lengths, you can always choose a focal length which will achieve the artistic effect and suit the situation you are trying to shoot. The best way to learn about focal lengths is to try. Instead of just standing in one spot and zooming in or out to get the frame you want, why not try and use a fixed focal length (prime) lens and move around to see the different perspectives you will get.