In discussion groups and photography groups you see questions about lenses from shoppers and the number one thing they want to know is if a lens is “sharp.” What many beginning photographers don’t understand is that lenses are not sharp at every aperture value and at every possible distance (especially with zoom lenses). Therefore the responses one gets on these forums will likely be very subjective and based upon that photographer’s experience and how they use that lens. If a person reports a lens is "not sharp" they may not be giving you accurate information. Every lens has a “sweet spot” and sharpness is often confused with depth of field. This article will help clear up that confusion and help you figure out what your lens' "sweet spot" is and how to find it.
First, some background information, no lens is ever perfectly sharp. Lenses are designed for maximum performance based on what manufacturers believe the main function of that lens will be. For example, if you purchase a zoom 70-200mm lens, the manufacturer might assume that the main use of that lens will be at the 200mm end of the range and they will maximize its performance for that focal length. A lens that is a macro lens will be maximized for close up shooting distances. Never purchase a lens and expect perfect sharpness at every distance, aperture, and zoom level. Know what you will be using the lens for and buy a lens designed for maximum performance for that purpose.
Another common point of confusion for beginning photographers is understanding the difference between sharpness and focus (or depth of field). Sharpness is related to resolution and depth of field is related to how much of the image is in focus from foreground to background. When you are first learning photography you will probably hear the advice that if you want more of your image in focus to use a narrow aperture (larger f/# like f/11 or even f/16). While generally this is true, greater depth of field (or focus) does not always mean more overall sharpness.
A quick side note: Using smaller apertures will increase depth of field, but the depth does not increase equally in front of and behind the subject. Instead when you stop down your lens, the increase in the depth of field behind your subject will be almost twice as much as in front. In other words if the overall depth of field increases to 20 total feet, about 1/3 (~7 ft) of this will be in front of the subject and the remaining 2/3rds (~13 ft) behind the subject. (If you need a refresher or introduction to depth of field and hyperfocal distance check out our previous blog posts).
I took three photos of a flowering tree using f/4, f/5.6, and f/22. The photo at f/4 has the most narrow depth of field and the photo taken at f/22 has the widest depth of field, while the f/5.6 (not shown) would be somewhere in between. While there is more in focus (greater depth of field) in the photo taken at f/22, it is probably not as sharp compared to the in-focus parts of the same picture taken at f/5.6.
We can examine the sharpness by "pixel peeping" and looking at only the areas that were in the zone of focus. We should find that the image is sharper at f/5.6 and less sharp at f/4 and f/22. The image taken at f/5.6 will appear “sharper” even though more of the area of the scene (depth of field) is in focus at f/22.
Now let's actually take a look at those images below. The series of shots was taken from the same location and only the aperture was changed. These are parts of the same photos shown above that demonstrated depth of field taken at f/4 and f/22 (plus the additional shot at f/5.6). Note that the original images were already cropped and then I further cropped in on just one flower that was inside the depth of field (in the area of focus). At this "pixel peeping" level we can compare the sharpness. Remember that when not cropped to show detail, each of these photos "looked" sharp and in focus in this area of the image. The focus and focus point were not changed in between shots so any differences you see are not because of a focusing issue. We can see that none of the images are perfectly sharp, but the one in the middle is the best. The issue/difference between these images occurs because of the internal workings of the lens. All those glass elements have to align and at different apertures the quality differs.
Lenses are “softer” at both extremes of aperture – wide open and mostly closed. The details in an image won’t be as crisp or “sharp” when shooting at the maximum apertures like f/1.4 (or in the case above with my lens at f/4), or at minimum apertures like f/22. Both extremes are equally deficient when it comes to sharpness. As a general rule the maximum sharpness, or “sweet spot” of a lens is 2 to 3 stops from the maximum aperture of that lens. So for example, if the maximum aperture of a lens is f/2, then the “sweet spot” would be between f/4 and f/5.6.
The lens used for the photos above has a maximum aperture of f/4. Therefore the "sweet spot" should be between f/5.6 and f/8. The image at f/5.6 gave good results, but with further testing, I believe this lens would probably be sharpest around f/6.7 or f/7.1 which is about one and 1/2 stops above the maximum.
Once you know the range of where the “sweet spot” should be, it is easy to conduct a test to find it with more precision. To conduct the test you will need to use Aperture Priority Mode. In Aperture Priority mode we can set and test the aperture and the camera will set the ISO and shutter speed.
If you are unsure of how to switch to Aperture Priority and how to change the aperture settings in that mode, you may need to consult your camera manual (we have most manufacturers’ links here). If your camera allows you to use one-half or one-third stops, make sure that is selected in your settings.
To perform a test to find the “sweet” spot of your lens, first find the maximum aperture of the lens and add one half or one full stop to that number to use as your starting point. If your lens has a maximum aperture of f/3.5 (most kit lenses), then start at f/4.8 or f/5. If your lens has a maximum aperture of f/2, then start at f/2.4 or f/2.8.
Go outside in good sunlight. Use a tripod or something to stabilize the camera and to keep it in position between shots. You will need to take photos of something that is about 10 feet away (like my sample images of the flowering tree) and make sure your focus point is on that object. You will not recompose or refocus in between shots (after getting your focus point you can change over to manual focus to make sure your focus point stays set).
Start by taking a photo with the aperture at your starting point (from above). Then turn the aperture dial 2 or 3 clicks narrower (bigger f/#) and take another photo. Then turn the dial a few more clicks and take another photo. Take test shots from your starting point up to about f/11.
By taking a test shot every 2-3 clicks you will be sampling a range of f/stops that include some half and third stops. The “sweet spot” may not be at a full stop like f/5.6. If your camera only has full f/stops, then take sample test shots at each full stop.
Now it is time to "pixel peep." Upload your photos and zoom in on each one. Examine the area of the photo that contains the object you focused on (that was about 10 feet away) and examine that same area in every photo. You should be able to tell which aperture gave you the sharpest image.
You can then repeat the test using the range of apertures in 1/2 and third stops around that aperture to further narrow it down. In my test above f/5.6 was the sharpest, but to really narrow it down I would test again starting at f/4.8 using every increment up to about f/7.1 (I already had an image at f/8 that was not as sharp so I know I can stop before that point).
Once you know the "sweet spot" make a note of that aperture for that lens. Repeat for different lenses. Each one will have a different “sweet spot” but typically the maximum sharpness will be about 2 stops above the maximum aperture, somewhere in the range of f/4 – f/10.
If your lens is a zoom lens the sharpness and “sweet spot” may not be identical throughout the zoom. For example, I have a Tamron 18-400mm and the maximum sharpness at 18mm may not be the same aperture setting when shooting at 400mm.
We could not ever hope to detail all the possible parameters for every lens in the marketplace in a short article like this, but we can offer a little general advice. If you are ever out and about and need a sharp image and you are not sure what the “sweet spot” of a particular lens is, then use Aperture Priority Mode and take a series of photos from f/4 through f/11 and you will have all your bases covered!
Another often overlooked way to help improve image quality and sharpness is to use a tripod and a shutter remote. These reduce camera shake.
So in summary, shooting with a wide open apertures may result in reduced sharpness in your images. Additionally the narrow depth of field can be difficult to work with. At very low apertures this depth can be less than an inch and can cause one part of a face, like the eyes, to be in focus and the nose out of focus.
When examining your images to trouble shoot a “non-sharp” image, consider both the depth of field (focus) and sharpness (resolution) as separate factors even though both are related to aperture. Decide if the lack of “sharpness” you see is due to missing your focus point while using a very narrow depth of field, or if it is an overall resolution issue due shooting at the extremes of the lens’ aperture range.
Knowing that your lens has a “sweet spot” and how to find it can help improve your images overall, but much about photography comes down to compromise. Just because your lens has a “sweet spot” doesn’t mean you should always use that aperture. When out in the field you may have to decide which is more important; maximum resolution (sharpness) or depth of field. It may be that you want the wider depth of field for a landscape shot and to get that you may have to sacrifice some level of sharpness. Also, remember, that to see the difference in sharpness you may have to “pixel peep.” The actual difference in sharpness between two images in normal print sizes may not even be that noticeable to the naked eye (even though they are there). “Pixel peeping” can become a dangerous obsession. Don’t let the search for optimal sharpness interfere with your creativity and the fun and joy that photography can provide.
Wide depth of field is especially desirable for landscape photography. This is where understanding hyperfocal distance becomes important. If you are just starting out, it will be important to understand the basics of depth of field, so before you continue reading, you might want to check out that blog post first.
What is hyperfocal distance?
Hyperfocal distance, in a nutshell, is the point in the foreground that is the closest point the camera can focus while still having acceptably sharp image quality throughout the rest of the image to “infinity” (which is the background/horizon in most images) In other words, it is the point of focus that will yield the greatest depth of field.
When composing an image, if the focus is on the foreground, then the background will be blurry. In a portrait shoot, whether for people or animals, the subject can be in focus and the background can be blurry, and that is normally desirable.
If the focus point is changed to focus on the background, then the foreground will be blurry. When capturing a distant mountain at sunset from an overlook, one can focus on the horizon or “infinity” and won’t notice the blurry foreground because there are no objects in it.
Understanding hyperfocal distance is only important when there are objects both far away and close up that need to be in sharp focus. Focusing at a point in between the close and faraway objects becomes necessary. The calculation of where this point is will depend on several factors like the focal length, the “circle of confusion” for the camera sensor, and the aperture (see the depth of field blog post). When we find the hyperfocal distance point, “acceptable sharpness” will be found throughout the image.
Acceptably sharp – what is that?
Imagine a photograph is hanging on the wall. It is an 8”x10” size photo. If a person with good vision (20/20) stood 10 feet away, and the image looks completely in focus to them throughout, then it is “acceptably sharp.”
The hyperfocal distance point does not create an equal amount of focus in front of and behind the focus point. Depth of field is always greater beyond the subject/focus point than in front of the subject. For example, one-third of the distance may be in front of the focus point and two-thirds behind it. There will be areas that are blurred, but the size of the blur is so small the human eye cannot distinguish the blur from a point of light. This is known as the circle of confusion. There are specific calculations for this and it becomes complicated very quickly (see depth of field blog post for an introduction to “circle of confusion”). While there are a lot of scientific and mathematical calculations that can help locate the hyperfocal distance point, some ways are easier than others, and where the best focus point is may depend on the circumstances of each unique landscape and the particular taste, artistic style, and preference of the photographer. So let’s start there…
Which is better to have in focus, foreground or background?
Since it is a given that some area of a photo will always be out of focus (even if it is so small one can’t see it without pixel peeping or blowing the image up to super large sizes), which is better to have in focus? This will depend on the characteristics of the image one is composing and one’s personal tastes.
Expert photographers have discussed and taken opposite positions over the years. On one side, some photographers suggest that faraway objects need crisper focus in order to be recognizable and that the loss of detail is especially noticeable in enlarged prints. They claim our eyes will be more forgiving if objects in the foreground a slightly blurred. To use this in practice, one would focus beyond the hyperfocal distance (maybe even use infinity) and then adjust the aperture (f/stop) smaller and smaller until foreground objects become focused enough.
Other photographers claim the loss of focus on nearer objects is more noticeable and disturbing and that background focus can be less sharp, especially if they are large and easily identified objects like a mountain. In practice, a photographer would focus at hyperfocal distance or in front of the hyperfocal distance, and again make changes to the aperture (f/stop) to get crisper foreground focus.
Gazebo in Autum - Image by FocusEd Camera
How do I find the hyperfocal distance?
With the exception of a few readers who are math wizards, most of us don’t want to have to do hyperfocal distance calculations on the fly while out in the field. Fortunately, there are hyperfocal distance charts and apps like DoF Table, Digital DoF (my favorite), and PhotoPills that can provide a good starting point for reference. Unfortunately, they are not always accurate and are one-size-fits-all, not taking into account the actual scene. Some lenses also include markings on the side of the lens barrel that give you these calculations, but the easiest method is to use the approximation method of “double the distance.”
How do I use “double the distance?”
A very simplistic way to achieve equal sharpness in the foreground and background is to use a method called “double the distance.” Find the closest object or element in your composition and determine (approximately – exact accuracy is not necessary) how far away it is from the camera sensor (not the end of the lens). Then double that distance and focus at that point. Use live view if available on the camera and use it zoomed in. This method does require some practice at estimating distances, but can be quite effective and efficient once one gets the hang of it.
Keep in mind that depth of field increases with smaller apertures, so if the closest object is not in focus at a certain aperture, then one may have to adjust the aperture. For example, if the camera is set up using a 35mm lens and the closest object that needs to be in focus is 8 feet away and f/8 is not working, increase the f/stop to f/11 or f/16 to bring the focus closer (increased depth of field). Other adjustments may then be required to shutter speed and ISO, so an understanding of the exposure triangle is also essential to achieving the desired outcome.
Should I use a hyperfocal distance chart?
As I stated before, a chart can be a great starting reference point. Find the focal length of the lens being used and the aperture settings, and it provides the closest point for focus where the background will still be “acceptably sharp.” A quick online search of hyperfocal distance charts will give you many options, but a quick look at the options also will demonstrate the inaccuracies I describe. One will find that the numbers don’t match from chart to chart. For example, I pulled up three charts and looked for the focus point if I was using a 24mm lens at f/2.8. The charts told me: 22.3 feet, 22.6 feet, and 21.1 feet. Now since most of us aren’t going to be pulling out a measuring tape to measure off 21 or 22 feet from our camera’s sensor, these numbers are close enough to give us a starting point. We would pick a point of focus that is approximately 22 feet from our camera’s position.
The apps for smartphones do these same calculations and are often a little more exact and definitely more convenient than carrying around paper charts. Unfortunately, these apps, depending on who made the app, can also be very inaccurate. Of the apps available, I prefer Digital DoF, which is free and often gives me good results to start with.
Do I need to know how hyperfocal distance works?
If one plans to take landscape photos, yes. Having an understanding of how hyperfocal distance works and changes with focal length and aperture will allow adjustments in the field that will improve image quality.
Hyperfocal distance moves closer to the camera sensor as smaller apertures are used. Remember smaller apertures make greater depth of field therefore the range of what is in focus moves closer and closer to the camera. The farthest reaches of the focus range are also getting larger, allowing the focus point to move closer (away from the horizon or infinity) while keeping the level of acceptably sharp focus both in front of and behind the focus point.
As the focal length on a lens gets longer, the hyperfocal distance moves farther away. This does not mean, for example on an 85mm lens at f/11 and a hyperfocal distance of 70 feet, that everything closer than 70 feet will be out of focus. On the contrary, the image will be sharp from halfway to 70 feet (35 ft) all the way to infinity. Anything 35 feet or closer will start to lose focus. Remember, double the distance? This is that same principle in reverse.
If you only use a chart, you will be constrained by the limitations of the chart. Going back to “acceptably sharp” focus for a moment, we come across the first limitation of a hyperfocal distance chart. They rely solely on the math calculations that include the “circle of confusion” (which I have also already explained is quite complicated and an internet rabbit hole all its own should you choose to go down it). The problem is that in camera-land long ago and far away, the circle of confusion was set at .03mm to create those charts. For technical folks, that .03mm is the size of the out-of-focus tiny points of light on your camera sensor and they are roughly circular. That .03mm standard is too large for today’s high resolution prints, computer monitors, and cameras, so the charts can’t be the “end all” tool you use.
The second problem, is that the charts (and many of the apps) are one-size-fits-all solutions for all lenses and in the field that does not take into consideration the vast array of possible landscape situations one may find oneself in. Where you should focus should change depending on the scene in front of you!
Let’s look at this this way – we have two very different scenes and for both compositions we are using our 35mm on our full frame camera at f/8.
According to the chart, for both of these should be focused at 17 feet in front of where the camera is standing. Using the chart we would have acceptably sharp focus for both images, but all that means is that both images will have the exact same amount of blur (0.03mm for each pinpoint of light to be exact).
Does that even make sense if we think about it logically? Of course not, the focus point should depend on the scene! For image 2 with the hot air balloon, if there is no foreground why would we want to focus at 17 feet in front of the camera? We wouldn’t, we should focus out at the horizon at “infinity.”
So the takeaway is to start with a reference point, either from a chart, app, or double the distance method, then know how to adjust the hyperfocal distance point and lens focal length and/or aperture to get the best overall sharpness for all images, not just acceptable sharpness for some of them.
Why can’t my camera just calculate the hyperfocal distance and tell me what it is?
Let’s say we are shooting a meadow with a tree off in the distance and even farther away is a mountain range. Let’s also assume the camera can give us a readout to tell us what the hyperfocal distance would be, say its 237 feet. How would we be able to put that into practice? Would we pull out a 237 foot measuring tape or cart around a measuring wheel with us on our shoots? What if there was a lake between us and the mountain and 237 feet puts us into the water? In practice, getting a readout on a camera would be no more accurate than using a focal distance chart or app (taking into account the camera sensor’s circle of confusion and lens focal length/aperture). That readout wouldn’t help that much more than just using the “double the distance” method, although I expect cameras will be adding more features like split screen focus, focus peaking, and live view modes that will make the process of finding hyperfocal distance easier.
So if Double the Distance is easy and works well, how would I use it in practice?
Let’s go back to the example I gave above of a bike rider in the city. The first step in our approach would be to determine if there are any foreground objects nearby – like a fire hydrant or a parked car. Whichever object is closest to the camera that we want to be in focus, we approximate that distance and then double that number. Our focus would be at that distance.
Let’s look at this sample image. If we assume the dog and the rocks around him are approximately 15 feet away, then the focus point should be double that distance, which is about 30 feet away. Voila!
The best part about this method is that it doesn’t matter which camera or aperture setting or lens focal length is being used; it works for all landscapes. Now this isn’t to say that camera settings are not still critical. They are! For landscape photography we use smaller apertures like f/11. If we did set the aperture to f/4 and use the double the distance method and focus 20 feet away, it will still give us the most sharpness in the scene, but it is probably not going to give us the image we would want.
It is important to also know the limits of the lens being used. Lenses are not their sharpest at either end of their range. For example a lens that will shoot at apertures from f/1.8 up to f/22 will not be at its sharpest at either extreme. And understand focal lengths. When trying to capture landscapes, an 85 mm or 200 mm are not the best lens choices, one will want a wider angle lens and even more so if using it on a crop sensor camera body. See my blog about lens focal lengths here.
To be completely honest, even if you learn all the background information and understand the concepts, no technique for hyperfocal distance will be perfect even with adjustments in the field. Chasing “perfect” sharpness is like chasing the end of the rainbow.
If you are glutton for punishment, and just can’t get enough about hyperfocal distance, then check out our next blog post about other hyperfocal distance calculation methods and trouble-shooting hyperfocal distance while on the go. Additionally we will discuss ways to work around the limitations of lens focus depths by using focus stacking and bracketing to make composite images.
If this is enough information for you, then let me leave you with one final thought, remember that for almost all images you compose and shoot, that “good enough” is better not taking the shot at all.
Forums and Facebook groups are full of someday want-to-be professional photographers and an extremely common question they ask as beginners is “How do I get that blurry background in my photographs?” The blurry background, or bokeh, is an effect accomplished by knowing how to create a shallow depth of field. It is a compositional tool used in many genres of photography such as portraits, flowers/nature, and products. A quick word of caution, overuse of any one compositional tool can create a portfolio that is, well… boring. So don’t rely only on “blur” to create memorable images. Check out our blog post on Composition Basics here.
While bokeh creates a pretty effect for many images, some genres require crisper focus throughout and blur is not desirable. Landscape, night photography, and some types of street photography are examples where a wider depth of field is common. To accomplish this wider depth of field, hyperfocal distance is often used. (You can read about Hyperfocal distance in next month's blog, but it is recommended you first have a solid understanding of basic depth of field and factors that affect it as discussed in this post).
What is Depth of Field?
Simply put, depth of field is the distance between the nearest and farthest objects in an image that are in acceptably sharp focus. In some photographs, everything seems to be in focus throughout and in some photographs the foreground or background, or both, may have blur. This is achieved by manipulating the factors that affect depth of field.
Depth of field is calculated using the lens’ focal length, distance to the subject, the acceptable “circle of confusion” size, and the aperture setting of the lens. Thus by changing one or more of these factors, different depths of field can be created. Let’s investigate the effects of each factor on the depth of field, starting with shallow depth of field.
How does one get shallow depth of field?
Shallow depth of field, also called a small or narrow depth of field, means that only a part of the image is in focus. Most often this is accomplished by using a wide aperture (small f/stop number) on the lens and shooting in aperture priority or manual mode. If a lens has the ability to shoot at f/2 at its most open setting, the resulting depth of field will be small or narrow. If that same lens was set at f/22 and its position and the subject/background positions are not changed, the result will be a much deeper or wider depth of field.
In these images above, the only factor that was changed was the aperture, or f/stop. Notice in the first image shot at f/32 there is more of the image, from front to back, in focus. The main flower and the flowers behind it are more defined and the bars on the iron door can be seen. In the second image, the aperture setting was changed to f/5 so much less of the image is in focus. There is more blur behind the main flower in this image and the bars on the iron door are completely out of focus, so much so, they almost disappear into the background. This is one advantage of a blurry background; to get rid of distractions behind the subject.
Shallower depth of field can also be accomplished with longer focal length lenses or by changing relative positions of the camera, the subject, and the background. A photo taken in close range will have a much smaller depth of field. Moving the camera closer to the subject and moving the subject farther from the background will increase blur in the background and make the depth of field narrower. For example, a portrait photographer will want to put some distance between the person/subject and the background to get the desired blur effect. A flower photographer might use a longer focal length lens to get a smaller depth of field and blur behind the bloom.
The images below demonstrate this effect. In the first image, I was much farther away from the flower arrangement which produces a wider depth of field. Some of the background, like the door behind the flower arrangement, were already somewhat blurred, but most of the flowers in the arrangement are in focus. In the second image, I have moved closer. There is a narrower depth of field. At this very close range, the background is fully blurred.
A camera can only get precise focus at one exact distance from the lens. Everything in front of or behind that distance will be blurred. The blur “spot” will be shaped like the aperture of the lens, thus almost a circle. If these spots, or circles, are small enough they are almost indistinguishable from a point of light and they appear to still be in focus. When this happens we have acceptable sharpness or acceptable “circle of confusion.” The “circle of confusion” size is related to a camera’s sensor size, and is a complicated concept that could be a whole article in and of itself. Any blur one can see in a final photograph is simply the blur spot as it registered on the camera sensor, only enlarged (on your screen or in print). How big this blur can get without being noticeable, is the acceptable "circle of confusion" size.
The take-away here, is that even the most crisp looking landscape image one has ever seen actually has areas that are out of focus or blurred, it’s just the blur is so minimal one’s eyes can’t tell unless the image is magnified or the viewer gets closer. The mechanisms of the camera and the way light bends as it enters the lens makes it impossible to have an image that is totally in focus from edge to edge at every given distance.
How depth of field and the “circle of confusion” changes from a crop camera to a full frame isn’t something most photographers will need to know. If one plans to make super-sized prints or enlargements, then it might be beneficial to know the sensor size and "circle of confusion" calculation in relation to the anticipated print size. More important for most photographers to understand are the effects of a specific camera body and lens combination on depth of field. Most photographers would not change camera bodies to achieve the depth of field they want when they can change position, lenses, or settings instead.
A full frame camera sensor will create a shallower depth of field when adjustments are made to keep the same field of view (remember a 50mm lens on a crop camera will only “see” the field of view of approximately an 80mm on a full frame – see our blog article on focal lengths here for clarification). Otherwise, this formula shows that depth of field is unaffected by sensor size if aperture, focal length, and distances are kept constant.
How do you get wider depth of field?
Wide or deep depth of field results in a much larger area (front to back) of the image being in focus. Basically by doing the opposite of any of the above, one can accomplish a wider depth of field. Using a shorter focal length (for example switching from an 85mm to a 50mm) or setting a larger aperture (from f/5.6 to f/11) will increase the size of the depth of field and make it deeper. The next set of images show the results of changing the focal length.
I remained stationary, but used the zoom on my lens to change the focal length from 18mm to 400mm (these images were also cropped to fit together). The shorter focal length in the first image creates a wider depth of field. The iron door is clear and the door knob appears mostly focused. In the middle image, the depth of field is narrowing. By the time I zoomed all the way in for the last image, the depth of field has become much more narrow and the only part that is really in focus is the solitary flower.
Changing the distance between camera and subject will also change the depth of field. If the subject is placed closer to the camera the depth of field is smaller. When you want to blur the background the subject should be closer to the camera, but keep some space between the subject and the background. If the subject is placed closer to the background, and the camera is moved farther away, the depth of field will be wider. In the example above, if I had remained in position after the third image and had moved the flower arrangement farther away from me (moving the subject farther from the camera), then the depth of field would have gotten wider again.
How is shallow depth of field used as a compositional tool?
In portrait photography, shallow depth of field creates that soft bokeh or blurry background behind the person (and sometimes in front of the person as well). The blur can give a photo a moody look or be used to create a dreamy, mysterious, or romantic “feel.” Additionally, the blur is sometimes used for an abstract effect.
The selective blur creates dimension and reduces distractions from the background. Since our eyes are drawn to and gravitate towards areas in focus, creating a composition where only some of the image is in focus allows the viewer to be guided to the subject. In portrait photography it is considered an important standard practice that the most crisp focus point be on the eyes.
Blur in the foreground can also remove distractions that are in front of the subject, like fencing around a cage, allowing the focus to be on what is beyond. In this image below, the wire fencing on the bird enclosure "disappears" and I am able to shoot "though it" even though my lens was several feet on the other side and the lens glass far too large to put between the wires.
Shallow depth of field is most often used in the genres of portrait, nature, travel, and to some extent street photography. With street photography, too much blur will take the subject out of context and the story behind the image can be lost.
How is wide depth of field used as a compositional tool?
Wide depth of field is desirable for landscape photography especially. This is where understanding hyperfocal distance becomes important.
Hyperfocal distance, in a nutshell, is the point in the foreground that is the closest point the camera can focus while still having acceptably sharp image quality throughout the rest of the image to “infinity” (which is the background or horizon in most images) In other words, it is the point of focus that will yield the greatest depth of field.
The hyperfocal distance point does not create an equal amount of focus in front of and behind the focus point. Typically, 1/3rd of the range of focus will be in front of the point and 2/3rds will be behind that point.
For a detailed look at hyperfocal distance and how to make calculations in the field, check out our hyperfocal distance blog next month.
There are hyperfocal distance charts and apps (like DoF Table, Digital DoF, and PhotoPills) that can provide a good starting point for reference, but they are not always accurate and they are one-size-fits-all, not taking into account the actual scene. Some lenses also include markings on the side of the lens barrel that give you these calculations, but the easiest method is using the approximation method of “double the distance.”
How do I use “double the distance?”
A very simplistic way to achieve equal sharpness in the foreground and background is to use a method called “double the distance.” Find the closest object or element in your composition and determine (approximately – exact accuracy is not necessary) how far away it is from the camera sensor (not the end of the lens). Then double that distance and focus at that point. For example, in the image below, if the closest rock that needs to be in focus is 10 feet away, then make the focus point 20 feet away (where the water ripples are). Use a small aperture (large f/number). Use live view if available on the camera and use it zoomed in. This method does require some practice at estimating distances, but can be quite effective and efficient once one gets the hang of it.
Keep in mind that depth of field increases with smaller apertures, so if the closest object is not in focus at a certain aperture, then one may have to adjust the aperture. For example, if the camera is set up using a 35mm lens and the closest object that needs to be in focus is 8 feet away (focus point 16 feet away) and f/8 is not working, increase the f/stop to f/11 or f/16 to bring the focus closer (increased depth of field). Other adjustments may then be required to shutter speed and ISO, so an understanding of the exposure triangle is also essential to achieving the desired outcome.
Image by strikers on Pixabay.
What is the take-away?
In summary, manipulating the depth of field is a compositional tool used by photographers in many genres. It is typically accomplished by changing the aperture of the lens, the lens focal length, or the positioning of the subject and background along with the positioning of the camera.
A shallow depth of field creates a nice blur effect in front of and behind the subject which results in a softer or more abstract feel, whereas, a wide depth of field has crisper focus throughout the image from front to back.
Knowing the calculations or keeping a focus distance chart is not necessary. An understanding of the exposure triangle, and the effects of focal length and aperture settings on your specific camera are essential. Practicing with your camera and lens in different settings is the best way to see the effects on depth of field in practice.
For improved landscape photography, narrow the aperture and use the “double the distance” method to get a wider depth of field. For portraits and flower blossom, put space between the subject and background and use a wider aperture or a longer focal length, or shoot in close range of the subject.
With an understanding of these basics, one will be ready to move on to a more detailed look at hyperfocal distance, or some practice with other compositional tools.
Disclosure: Some of the links below are affiliate links. Please read the full version of my disclosures for more information. If you make a purchase through one of these links, we make a small commission (at no cost to you).