A guide to focusing properly – and boiling it all down to 3 simple rules to help you while you are shooting.
Many photographers have it really easy when it comes to focus. Consider the portrait photographer. Do you know what the rule is for where to set your focus in portrait photography? On the eyes. Every time. There are virtually no exceptions. If the eyes are not on the same plane of focus, then you just focus on the near eye. That’s all there is to it.
It is also simple for those photographers that have a discrete subject. For example, wildlife photographers always want the animal in focus. They simply set their focus on it every time. If the animal is close enough, they will revert to the rule for portrait photographers and focus on the eyes.
Outdoor photographers generally have a more difficult time with focus though. There’s not always a clear and distinct subject to set your focus on. You are also often trying to capture an entire scene, so you need a whole range of things in focus. Other photographers are often happy to have their backgrounds become blurry. Not so with those shooting landscapes, seascapes, and cityscapes. You want them sharp.
Therefore, outdoor photographers generally need to understand the concept of focus more than others. In this article we will walk through the basics. It is necessarily tied up in other subjects, like depth of field, so we will get into that a little bit as well. After that, we’ll work our way into some practical rules you can use when setting your focus.
How Focus Works
When we get into how focus works, you do not need to get into the complexities of lenses or cameras. All you really need to know is this: when you set the focus, you are focusing on a distance not a thing. Once you set the focus, as long as you stay the same distance away from whatever it is that you focused on, it will remain in focus.
To see this for yourself, look at the top of your lens after you have set the focus on something. On many lenses, there is a scale on the top of it with a range of values. Those are distances. Looking at that will tell you how far away your focus is set. (If your lens doesn’t have this scale, don’t worry about it, you will rarely use it.)
The fact that your focus is set at a particular distance has a number of implications for your photography. The first is that since you are focusing on a set distance, everything at that distance will also be in focus. If you focus on a person that is 12 feet away from you and a cat and a dog are also 12 feet away from you in the same general direction, the cat in the dog will also be in focus. Everything at that distance will be at focus. This is referred to as a plane of focus.
In addition, notice that on the scale on top of your lens that as things get further and further away, the numbers stop and at some point there is an infinity symbol:
After some distance, everything is so far away from your camera that it doesn’t make any difference whether it gets any further away. It will all be in focus. When does that happen? It depends on the focal length of your lens. Wide angle lenses will go to infinity very quickly (after just 3 to 5 feet). Lenses with longer focal lengths will go to infinity after about 30 feet.
We will come back to this point later because it will have impacts on where you should set your focus.
The Impact of Depth of Field
When you focus on something 12 feet away, that doesn’t necessarily mean everything at every other distance is entirely out of focus. For example, if the dog in the example we were just talking about was 11 feet away and the cat was 13 feet away, they would probably still be in focus. You get some leeway. But how much leeway do you have?
The answer lies in the depth of field. Depth of field measures the range at which things will still be acceptably sharp as they move away from your point of focus.
As you probably already know, depth of field is controlled by the aperture setting on your lens. A large aperture will have a very shallow depth of field. That means only things that are very close to the point of focus will be sharp. Conversely, a small aperture will give you a wider depth of field, so things that are further away from your point of focus will still be sharp. In any case, there is always a gradual fall off from “in focus” to “out of focus.” The degree of fall off is what is determined by the aperture size.
This graphic shows you how it works, with different aperture sizes showing the range that will be sharp:
Measuring What Will Be Sharp
It is one thing to know whether the degree of fall will be a fast (as in a large aperture) or slow (as in a small aperture). But can you determine the actual distances involved? In other words, if you know you are focused on something 12 feet away and you know your aperture is set at f/8, can you work out whether or not something 8 feet away will still be sharp?
The answer is: Yes you can. But realistically you will never do that.
Let’s start with the “yes you can” part of that answer. If you have ever used old cameras and prime lenses, you may have seen the scale on the top of the lens. With those lenses, you would set the aperture of the lens and the point of focus. After that, you could look at the scale on the lens, and it would tell you how far away things will be sharp for that aperture setting. It looks something like this:
In this example, the center red circle shows that this lens is set to focus on something 5 feet or 1.5 meters away. The aperture is set at 16. The lens contains markings for the aperture settings that line up with other distances. Look at the left and right red circles. The left f/16 lines up with .8 meters (between 2.5 and 3 feet). The right f/16 lines up with infinity. This is telling you that your picture will be sharp at this aperture between .8 meters (between 2.5 and 3 feet) and infinity.
Unfortunately, modern lenses rarely, if ever, have this scale on them. Most of our modern lenses are zoom lenses, so it is not possible to have scale because everything changes per focal length. Therefore, you will never really use this measurement. Rather you will just get more comfortable with the distances involved over time. You’ll just have a feel for what aperture you will need to use to keep things sharp at given distances.
However, there is one measurement that will give you a good idea of the degree to fall off to out of focus, which is what we will talk about next.
Measuring Hyperfocal Distance
Next we are going to talk about hyperfocal distance. Before we do, let me assure you it is not that complicated, so do not let the name intimidate you. It is just the measure of a point beyond which everything in your background will be sharp.
Let’s say you want to set your focus as close to you as you can, but you still want the distant horizon of your picture sharp. The hyperfocal distance is that point. It is the measure of how close you can focus and still keep that background sharp. It comes down to three variables: aperture, sensor size, and focal length.
The good news is that you never need to worry about calculating hyperfocal distance. That work has already been done for you and is available in many different places. There are free online calculators. There are apps you can put on your phone. There are also charts available.
In fact, I have prepared some charts that you can use. Since hyperfocal distance is partially a function of the sensor size of your camera, I have different charts for different sensor sizes. Just pick the one that corresponds to your camera, print it off, and keep it in your bag.
Actually, just by taking a look at the chart and gaining some experience you will quickly find that you don’t need to worry about the actual hyperfocal distance. You will gain a sense of what will be sharp and what will not. Frankly, that’s good enough.
An example may help you understand this concept. Let’s say you are outside at a scenic vista and want to capture the entire scene in front of you. You want the background sharp and as much of the foreground sharp as possible. If you are shooting with a 24 mm lens on an APS-C size camera and have your camera set at f/11, you can look at the chart above (or use a calculator) and see that the hyperfocal distance is 5.9 feet (less than 2 meters). That means that the closest distance at which you can focus and still keep the background sharp is 5.9 feet. If that is close enough, you should find something about that distance away and focus on it. If you need to set the focus closer, then you’ll need to make your aperture smaller.
Practical Focusing Techniques
Now that you understand the principles involved with determining where you can focus, let’s get into the practicalities of focusing your camera. Let’s face it: are you really going to be out there with a calculator and charts trying to determine where to focus? Probably not. However, armed with the information I’ve already given you, I can now give you a few simple rules that will allow you to nail the focus virtually every time.
Rule 1: Focus on the Subject
First, let’s not overlook the obvious. If you have a subject at your picture, focus on it. The subject is the most important thing and it needs to be sharp.
Rule 2: Don’t Set the Focus at Infinity
Many times the outdoor photographer will line up a picture that is essentially of a background or some sort of scenic vista. In these cases, there is often nothing close to you that will be in the picture. In such a case, you might be inclined to just to set the focus at infinity. I admit that doing so is not a horrible idea and your picture will probably be ok, but there is a slightly better way.
Set the focus a little bit closer than infinity. How much closer? Usually somewhere between the highest number and the infinity symbol on the distance scale of your lens will do. If your lens does not have such a scale, just focus at infinity but then twist the focus ring a tiny bit so the focus draws slightly nearer to you. Why would you do this? To obtain as much range of sharpness as possible.
If you sent the focus on infinity, you are not taking full advantage of whatever depth of field you have. The focus will look something like this:
If you draw the focus forward a little bit, you will take advantage of the depth of field on both sides of the plane of focus. The amount of space in the picture that is in focus will be much greater. It will look more like this:
As you can see, you have effectively doubled the sharp area of the picture by drawing the focus a bit closer. In the top example where you focused on the furthest point from you, only the mountain was sharp. By setting the focus on the near base of the mountain, which is closer to you, both the mountain and the trees are sharp. You have taken advantage of the depth of field in front of and behind the point of focus.
Rule 3: Set the Focus No More Than 1/3 Of the Way Into the Picture
On many occasions, I’ve heard the rule in photography articulated that you should focus about a third of the way into the picture. I have used this guideline on many occasions and found it to be pretty useful. Therefore, I recommend it to you as well. Sometimes rules of thumb work really well. Why get cute and do something different?
In addition, having a sharp foreground is incredibly important for your outdoor photos. I cannot count the number of pictures I’ve seen that were ruined by having something blurry in the foreground. In fact, given the choice between (a) a sharp foreground with a slightly blurred background, and (b) a sharp background with a slightly blurry foreground, I will choose (a) the sharp foreground nearly every time. But you really shouldn’t need to make that choice, and I will explain why in a second.
Before we talk more about the suggested approach, let’s talk about another choice that might seem attractive to you. It might seem to you that you could just focus somewhere in the middle of the frame, set a really small aperture to maximize your depth of field, and fire away. The rationale would look something like this:
First, let me say that doing this isn’t the worst idea in the world. The wide depth of field will probably give you a sharp picture throughout the entire scene. You might use this approach if you are just starting out. But there are a few downsides to this approach:
- It Costs You Light. Using a smaller aperture than you really need means you’ll be letting less light into the camera. You’ll have to make that up to get a proper exposure. The only two ways to do it are to increase the ISO or lengthen the time the shutter is open. If you increase the ISO, you risk introducing digital noise into your picture. If you lengthen the shutter speed, you risk camera shake if you are hand holding your camera. Even if you have a tripod, there might be movement in the picture that is then blurred.
- It Adds Diffraction. Diffraction is a softness that occurs in pictures when you use a very small aperture. It is a scientific fact of life, and there is no getting around it. Check out The Evil That Is Diffraction if you want to know more about it. Some experts urge you to never use your lens’s smallest apertures so as to avoid diffraction. I don’t go that far, but I do urge avoiding its effect when you can do so easily (and you can here).
- It is Just Imprecise. Ultimately, just using a small aperture so that the wide depth of field covers your imprecise focus is just sort of careless and lazy. We can do better.
The fact is that you usually don’t need to use your lens’s largest aperture to achieve sharpness throughout your picture. Why not? To answer that, first let’s think about the typical outdoor photo. For landscapes, seascapes, and cityscapes, which is really what we are talking about here, you will generally be using a wide angle lens. That is certainly the case for me, and in perusing online galleries of such photos I find that upwards of 90% of all photos are taken between 16 mm and 24 mm. This matters because wider depths of field are much easier to get with wide angle lens. In fact, even if you tried to get a shallow depth of field on a super-wide lens, you’d have a hard time.
Looking at this another way, you may recall that one of the factors in finding the hyperfocal distance is focal length. The shorter the focal length, the closer the distance you can focus and still keep the background sharp. That means with a wide angle lens, we ought to be able to focus pretty close and still keep the whole background in focus. Looking at the charts, we see that with a full frame camera shooting at 20 mm, the hyperfocal distance is only 5.5 feet when shooting at f/8, or 4 feet when shooting at f/11, or 2.7 feet when shooting at f/16. Those are really close!
Given all this, if you just pay attention to what you are doing, you will find you rarely need to use the smallest aperture to keep everything in your picture sharp. Again, when you are out shooting you won’t want to be worrying about numbers, so we need to keep this simple. Therefore, I revert to the rule of thumb that you can just focus on something relatively close – no more than a third of the way into the picture – and your focus will achieve the goal of keeping everything sharp.
The Process: Focus then Compose
So now you have figured out where you want to focus and what you want the picture to look like. The trouble is, what you want to focus on is not always in the center of your picture. So how do you set the focus and still compose the picture you want?
The answer is to move the camera around to focus it, set the focus, and then move the camera to the composition you want. In other words, if there is a boulder 6 feet in front of you that you want to use to set your focus, but you want it on the left side of your composition, just move your camera to focus on the boulder, hold that focus, and then move the camera to compose the picture you want. Stated more simply: move to focus, hold the focus, then move to compose. That’s it.
How you go about doing that will depend on how your camera is set up. If you use back button focus, the process is easy. You simply press the button on the back of the camera that operates the focus, move the camera into position to take the composition you want, and take the picture.
If you do not use back button focus, it is still not hard. You center the item that you want to focus on in your frame, press the shutter button halfway down, and then while holding the shutter button down move the camera to set up the composition you want. Then take the picture.
Nailing the Focus in Outdoor Photography
So where should you set your focus for outdoor photograph? The answer is usually: closer than you think. Essentially, my advice boils down to 3 simple rules to help you while you are shooting.
Remember that landscapes, seascapes, and cityscapes are unique in that they have a wide range of distances in the picture and you want to keep all those distances in focus. Most other types of photography don’t have such a wide range of distances and even where they do, you often want the background blurred. Putting depth of field to work for you typically means you should focus closer than you might otherwise be inclined. That leads to the first two rules:
- Where everything in your picture is far away, putting the depth of field to work means you will draw your focus slightly closer than its furthest setting.
- Where there are items close to you that you want in the picture, focus closer and rely on the wide angle of your lens and the depth of field to keep the background sharp. You don’t need to get precise with hyperfocal distance, just have a sense of it.
And, of course, let’s not lose sight of the final rule:
- if you have a subject in the picture, focus on it.
Following these simple rules will keep your picture sharp where it matters without worrying about any numbers or specific distances. If it seems complicated and time consuming now, it won’t as you gain experience. In time, it will become second nature and you won’t even think about it.