Image Sharpness

The Ultimate Guide to Sharper Images

When you take a photograph, it's an attempt to capture emotions and memories to save them for later and to share with others. When you and others look at your photographs later, you want those images to recreate all the memories and emotions of the original experience. When those images in your photographs are blurry rather than crystal clear, it's frustrating, very disappointing, and even, possibly, at least a little heartbreaking. No matter what type of digital camera you have, though, you can learn how to eliminate the problems that produce blurry images so that you never have to be frustrated, disappointed, or heartbroken again.

What’s Behind Those Blurry Photographs?

The causes of blurry photographs range from the ones that probably come to mind easily to ones that may seem complicated and technical, but even the ones that seem complicated and technical make sense once they’re explained. Once you understand the problems that create blurry images, you can easily correct them. Here are the culprits:

blurry, lack of sharpness, Poor Focus
  • Your subject moves.
  • The camera moves (called “camera shake”), usually, but not always, because you moved while holding the camera to take the picture.
  • The camera’s autofocus system didn’t focus on your subject properly.
  • The settings that affect the exposure of the photo – ISO sensitivity, aperture, and shutter speed – (the complicated, technical sounding causes, but don’t panic yet) didn’t work together properly to create the best image.
  • The camera lens or its image sensor needs cleaning.
  • Your vision has changed, and you need to visit your optometrist for an eye exam.

Subject Movement -- Straitjackets Are Not the Solution

You cannot put living subjects, like people and pets, into a straightjacket, no matter how tempting the idea is, even if you are taking a portrait shot. Even in portrait shots, people may blink, sneeze, cough, become distracted and look away, take care of a nose that has begun to itch, or move for some other reason. A straightjacket just is not an attractive look to wear for a portrait, and the look on the unhappy face of your subject wouldn’t be very attractive, either.

Digital cameras deal with this challenge in various ways.

Dealing With Subject Movement in Portrait Shots

Among the ways that digital cameras deal with moving subjects in portrait shots are:

  • Blink detection systems that alert you if someone in a portrait shot might have blinked.
  • Storing a few seconds of video taken before you push the shutter button along with the image taken at the moment you snapped the shutter.
  • Taking a series of images when you push the shutter button.

Dealing With Subjects With Places to Go and Things to Do

running camel

When you plan to capture still shots of sports, stage performances, kids and pets, or other types of action photography, you know that your subjects will be in motion. They have very important places to go and things to do.

Digital cameras handle these situations with:

  • The continuous focus setting for auto focus.
  • Shooting a series of still images.
  • Manual adjustments to the exposure settings – the size of the aperture opening, the speed at which the shutter operates, and the ISO sensitivity which compares to film sensitivities for film cameras.

Your Camera Shakes Things Up

A number of things can cause camera shake, and it isn’t always the photographer’s fault. Camera shake occurs when:

  • The photographer moves. This one is solely on the photographer, sorry.
  • Vibrations that affect a camera mounted on a tripod due to wind, traffic vibrations, the movement of a shutter release cable, or someone touching the camera.
  • The mirrors within the camera lens move while the camera is mounted on a tripod, called mirror slap.

Your Camera Just Can’t Focus

With face detection, smile detection, pet detection, and other features, you may fall into a false sense of security, thinking that auto focus systems are infallible. They are very, very good, but they can fail to focus, fail to focus on the right subject, or lose their lock on the subject.

This happens because: 

  • Auto focus expects to find the main subject mid-ground at the center of the picture, because that’s how most pictures are composed. If your subject is in the foreground, the background, or off-center, your camera is likely to select and focus on the wrong subject.
  • In portrait mode, cameras focus on the face closest to the camera, treating that person as the main subject. In a group portrait, though, you may want the focus on someone else.
  • Camera’s have mistaken something that’s not a face for a face.
  • When camera’s use face recognition to focus, they can lose focus if the subject turns his or her head or fail to establish focus if the subject isn’t facing the camera.
  • If you try to take a picture through a window or glass case or if there is an object in the foreground, your camera may focus on the glass, a window screen, a speck on the camera lens, or some object in the foreground such as leaf, a piece of furniture, or a decorative room décor item.
  • Cameras can fail to focus on subjects that are too close to the camera.

Focusing for Wide Angle Photos vs. Long Distance Photos

Cameras may have trouble determining what to use as the focus point in either of these situations. Consequently, the camera may leave the edges of a wide angle shot, such as a landscape, in soft focus, or it may capture too much of the scene and not focus in sharply on your intended subject.

Wide Angle Photos

Your Camera Becomes Oh, So Sensitive

Certain settings can leave your camera too sensitive and sharply focused. When that happens, you’ll see spots throughout your picture, called noise, graininess, or pixilation. The same thing happens when you over-sharpen an image with your photo editing software.

It’s Not Your Camera’s Fault

Dust or smudges on your lens or dust on your image sensor translate to specks and smudges on your pictures.

In addition, if your vision changes, it changes how well you are able to see your subject, and that, too, can affect how well you focus your photographs.

What Are We Talking About?

Before things get confusing, here are some explanations of the terms we’ll be using:

Sharpness and Contrast

Sharpness refers to how clear and well-defined the details, edges, and lines are in an image. Contrast refers to the amount of difference between the dark, shadowed areas of the image and the bright sunlit or artificially lighted areas of the image. An image can have little contrast between the lightest and darkest areas but still have sharply defined details, lines, and edges. Conversely, an image can have a high degree of contrast between light and dark areas and still lack sharp definitions of details, lines, and edges.

Focus and Auto Focus

The focus is the point at which the light from the view seen through the camera’s lens converges to form a clear, sharp, well-defined image on the film or the camera’s image sensor.

Auto focus is the system that your camera uses to focus on a subject automatically, and it can be an active system, a passive system, or a hybrid of an active and passive systems or two passive systems.

Active systems bounce sound waves or a beam of infrared or laser light off of the subject and then measure the length of time it takes the sound or light to return to determine the distance to the subject. These active systems are able to focus even in the dark, but they cannot focus through a glass case, a window, or window screens because the emitted sound or light will bounce off of the glass or the screen before it reaches the subject. The emitted sound or light may also bounce off of some other object that comes between the camera and the subject, causing the camera to fail to focus properly. In addition, active systems can have trouble focusing on subjects that are too close to the camera, making macro photography problematic.

Passive systems focus by examining the image received by the camera without actively emitting any sound or light for the purpose of achieving focus. Instead, passive systems use either contrast detection or phase detection to achieve focus. Because passive systems require an image from the camera in order to focus, they cannot focus in complete darkness, as active systems can. They require an auto focus assist lamp to emit a brief flash of light, preferably infrared light, so that the camera’s image sensor can acquire an image. Infrared is preferred because it is the least likely to be noticed by live subjects, so it is the least likely to startle or disturb subjects. Passive focus systems can have problems focusing on subjects with little or no contrast; soft, ill-defined edges; or repetitive patterns.

Contrast detection systems compare the contrast between adjacent pixels in the image. These systems determine when the correct focus is achieved by determining when the most intense and distinct contrast among adjacent pixels is reached. However, detecting and determining the sharpness of the contrast between pixels is achieved without any measurement of the distance to the subject, so if the optimal level of contrast, and thus the optimal level of focus, is lost because the subject moves, contrast detection systems have no means to regain focus by tracking the subject.

Phase detection systems work in a way that is similar to the point in the eye exam when your optometrist splits the image you see into two images and asks you to signal when they merge back into one. Phase detection systems, however, measure not only the separation between the images from side to side but also from the forward focus position to the rear focus position. This gives these systems a reading not only on the distance to the subject’s position but also the direction to the subject’s position and the likely direction and speed of any movement.

In tracking mode, which is also known as continuous focus mode or AI (Artificial Intelligence) servo mode, the camera uses predictive software algorithms along with changes in the distances between the split images from side to side and front to back to track the distance to and speed and direction of a moving subject or subjects in order to maintain focus.

Hybrid focus systems combine two focusing systems that compensate for each other’s weaknesses. A common hybrid system pairs phase detection and contrast detection. This enables the camera to track and keep one or more moving subjects in a general state of focus and then use contrast detection to bring them quickly into sharp focus when the shutter button is pressed. If a camera offers tracking and smile detection, it has a hybrid phase and contrast detection system.

Manual focus allows you to focus the camera when auto focus has difficulty focusing or when it focuses on the wrong subject. Some cameras allow you to use the camera’s LCD screen as a touch screen and move the symbol for the active focus point over the area where you want the camera to focus. Others allow you to use up-down and right-left arrows to move the focus point.

Alternately, you can use the focus-and-recompose method. Move the camera to your chosen subject, push the shutter button halfway down to lock the focus on your subject, and then move the camera to recompose your shot and press the shutter the rest of the way down.

Another alternative offered by some cameras is back-button focus. These cameras allow you to program a button on the back of the camera to auto focus the camera so that pressing the shutter halfway down no longer locks the focus of the camera. You can then use the button on the back of the camera to lock your focus on an off-center subject, recompose your shot, and then depress the shutter all the way down without having to hold it halfway down while you recompose your shot.

Using the shutter priority, aperture priority, or full manual mode gives you even more control of your camera’s settings.

Shutter priority allows you to set a low shutter speed to let in more light while the camera automatically chooses the width of the aperture and the ISO sensitivity.

Aperture priority allows you to choose the width of the aperture opening while the camera automatically selects the shutter speed and the ISO sensitivity.

Full manual mode allows you to adjust the aperture, the shutter speed, and the ISO sensitivity until you find the best balance between those three settings.

Depth of Field

Depth of field refers to how much of the foreground and background of the picture is in focus.

If you are focusing tightly on your subject, such as for a portrait, a sports action shot, or a long distance, telephoto shot, you don’t want objects in the foreground or background to distract from your subject. Using lenses and camera settings that restrict the camera to a shallow depth of field that keeps a tight focus on the area immediately around your subject deliberately blurs foreground and background distractions. Restricting depth of field too tightly, however, can leave part of your intended subject out of focus. A narrow depth of field also makes focusing the camera more difficult.

If you are photographing a large group, a building, or a sweeping landscape, you will want everything in the photograph to be in focus. Using lenses and camera settings that provide as much depth of field as possible bring foreground, mid-ground, and background into equally sharp focus.

Metering Settings

The metering settings tell the camera which area of the image to use to measure the amount of light your intended subject is receiving. The camera then uses that information to select the settings for the lens aperture, the shutter speed, and the ISO sensitivity when auto focus is in use.

Metering setting offer three choices – spot focus, center-weighted, or matrix.

Spot focus

uses a narrow depth of field to take a reading of the amount of light falling upon and immediately around your subject, and it is used for distant subjects in telephoto and action photography. 

Center-weighted metering

takes a reading over a larger percentage of the image with the priority give to the readings from the center of the image, and it can be used as a general setting for any image composed with the subject at mid-ground and more or less in the center of the image, such as a portrait shot. 

Matix metering

uses a grid to divide the image into segments and take a reading from each segment. These readings are then averaged, with each one given equal weight, to reach an overall reading for the entire image. Use this setting when you want the entire image well-lighted and in focus, such as for landscapes or images of buildings.

Aperture

The aperture is created by a set of small blades in the camera’s lens that open and close to control how much light is allowed into the camera, as well as how much depth of field the photograph will have. The size of the aperture is described in f-stops. A large, or wide open aperture with a low f-stop like f/3.5 lets in more light, but narrows the depth of field. A smaller aperture with a high f-stop like f/22 allows less light, but widens the depth of field.

The f-stop is a measurement of the diameter of the aperture in millimeters, and it is expressed as a fraction of the focal length of the lens. So, if you have your zoom lens set to a focal length of 100mm and you are using an f-stop of f/20, you would divide the focal length of the lens by the f-stop setting to get the diameter of the aperture opening, which would be 5mm. Thus, you would be letting more light into your photograph but narrowing the depth of field.

The focal length compares the width of the view visible through the lens to lenses used for film cameras. Lenses with lower numbers have wider views and greater depth of field, but lenses with higher numbers can focus on more distant subjects with a narrower depth of field for telephoto photography.

Shutter Speed

The shutter speed measures the length of time the shutter remains open in fractions of a second. Shutter speed controls both how much light the image receives and the amount of blur that could be introduced into the image. Higher shutter speeds reduce the amount of light that the image receives as well as reducing the chances that subject movement or camera shake create blur. Lower shutter speeds increase the amount of light the image receives but increase the chances of creating a blurred image. Blur isn’t necessarily a negative, though. It can be used deliberately to create artistic effects, as in time lapse photographs in which the shutter may be open for many hours.

When you are holding your camera rather than using a tripod, the rule of reciprocals offers a guideline for selecting a shutter speed that will reduce the chances of a blurred image. The reciprocal of a number is that number expressed as a fraction with the number “1” as the numerator and the number as the denominator. In photography, the rule of reciprocals states that when you are handholding your camera while taking pictures, your shutter speed should be faster than the reciprocal of the focal length of your lens. So, if you are using a wide-angle, 28mm lens, your shutter speed should be faster than 1/28 of a second. If you are using a 240mm telephoto lens, then your shutter speed should be faster than 1/240 of a second.

Faster shutter speeds that reduce blur but also reduce the light received need to be compensated with a larger aperture that lets in more light to keep your image from becoming too dark, but larger apertures reduce the depth of field, which may blur more of the foreground and background than you wanted and may even leave parts of your subject out of focus.

ISO

ISO stands for International Organization for Standardization, and the letters are pronounced individually as “I.S.O.” It controls how sensitive your camera is to the amount of light it receives and how “noisy” – grainy or pixelated -- your photos are.

The ISO numbers correspond to the film numbers for film cameras. The lower the number, the less sensitive the film and the corresponding camera setting, and the higher the setting the more sensitive the film and the camera setting are to the available light.

Lower numbers enable the camera to capture the details of scenes or subjects in bright or highly reflected sunlight, a situation that would cause a more sensitive film or setting to wash out the image and record only faint, faded images or only a glare of white.

Higher numbers compensate for lower light or the higher shutter speeds for action shots with an increased sensitivity that enables the film or the camera setting to quickly capture as much light as possible from what is available.

Therefore, an ISO setting of 100 or lower is for bright sunlight and scenes where the sun reflects off of water, sand, or snow. An ISO setting of 200 is for cloudy days, and an ISO setting of 400 is for lighted indoor scenes or action photography.

Digital cameras offer ISO settings above 400. Some offer an ISO setting of 3200. As cameras improve, they are able to use higher ISO settings more successfully, but there is a trade off between increased sensitivity and increased noise. Test your camera using the higher settings to find the range at which your images become grainy or pixelated.

7 Practical Tips for Getting Sharp Images Every Time

1. Holding the Camera

You need to provide a stable base when handholding the camera as you take pictures. You can provide a three-point base by holding the camera in your right hand with your index finger on the shutter button as your left hand supports the lens. Keep your elbows close to the sides of your body, and place the cup for the viewfinder firmly around your eye. Practice depressing the shutter button with a smooth, steady stroke.

If that doesn't work, you can try this other methode:

2. Choose the Sharpest Aperture Setting

While depth of field issues may prevent you from selecting the sharpest aperture setting for your lens, you should try to choose a setting that is as close to it as possible. The maximum and minimum apertures for your lens will be listed among its specifications. When you want to use a wide aperture setting, select one that is two to three f-stops below the maximum aperture for your lens. If that adds too much to the foreground and background around your subject, then at least reduce the aperture setting by 1/3 to 2/3 of a stop. Similarly, choosing an aperture setting one to two f-stops larger than the minimum aperture reduces diffraction, or the amount of light that disperses after it is forced to pass through the small aperture opening. Light also disperses after passing through larger apertures, but the percentage of light that is diffracted by passing through a small aperture is much larger than the percentage that is diffracted by passing through a larger aperture. Consequently, the softening effect of the light diffracted by a small aperture is much more noticeable. Opening up the minimum aperture thus improves the sharpness of the image.

3. Image Stabilization

Two types of image stabilization are available – optical and digital, and some cameras offer both. Optical image stabilization uses small gyroscopes in the camera lens to sense movement and compensate by adjusting the mirrors in the lens before and as you take the picture. These mirrors transfer the image from the lens to the camera’s image sensor, so the corrections are made before the picture is taken. Digital image stabilization uses the camera’s image processing software to compensate for movement after the photograph is taken. Image stabilization can be turned on and off, so make sure that it is turned on when you are taking photographs while you are holding your camera. With optical image stabilization, you can reduce your shutter speed by as much as three steps below the reciprocal of the focal length you are using for your lens. 

4. Use a Tripod

Whenever you use a slow shutter speed, a shutter speed that is slower than the reciprocal of the focal length you are using for your lens, mount your camera on a tripod. Both table top and adjustable full-size tripods are available. They are lightweight and fold and telescope so that they are easy to transport.

5. Trip the Shutter Remotely

When your camera is mounted on a tripod, touching it can cause vibrations that translate into camera shake. Even using a cable to trigger the shutter can introduce movement if you accidentally pull on the cable or a gust of wind blows it. Cameras have several options that you can use to trigger the shutter remotely. Most cameras allow you to set a timer to delay the operation of the shutter to allow everyone to get into the picture. Some cameras allow you to set the camera to delay the shutter until it recognizes a smile, a wink, or an additional face (the photographer's face) entering the shot. Other cameras allow you to take complete control of all of your camera’s functions from an app that you can install on your smart phone or tablet. 

6. Use Your Camera’s Auto Focus Points and Continuous Focus

When focusing your camera, select the auto focus point closest to your intended subject rather than moving the camera to point it at your subject, depressing the shutter halfway, and then recomposing your shot. Moving the camera to focus it means that you have focused on your subject in a different focal plane, or at a different angle, than the focal plane or angle in which you are shooting the picture. If you are shooting with a shallow depth of field, the difference in the angles could be enough to put some parts of your image into the unfocused foreground or background. In addition, using the auto focus points allows you to set them to track one, or with some cameras two or more, moving subjects, keeping them in constant focus. However, your pictures will be clearest with a single auto focus point.

7. Select the Focal Length of Your Zoom Lens, and Then Focus Your Camera

When cameras had to be focused manually, parfocal lenses would retain their focus when zoomed in or out. Many lenses are now varifocal lenses, though, and these change their focus as they zoom. This means that if you zoom the lens after focusing it, the focus drifts. Consequently, it’s best to select the focal length you need to best compose your shot and then focus your camera. In addition, attachments make it possible to use a wide range of camera lenses, but keep in mind that some camera manufacturers include contrast detection systems in their cameras but not phase detection. These lenses may not respond as well when the tracking function of phase detection systems is in operation. If your camera accepts interchangeable lenses and includes a phase detection system, as most do, be sure that the lenses you purchase for it are compatible with phase detection tracking.

7 Common Mistakes That Can Cause Poorly Focused Images

1.Forgetting to use mirror lock-up mode when using a tripod results in camera shake due to mirror slap.

2.Forgetting to turn off optical image stabilization also can result in camera shake if the gyroscopes in the lens sense movement in the tripod and unnecessarily attempt to compensate.

3.Forgetting to turn off continuous auto focus before adjusting the camera’s focus by using the focus-and-recompose method causes a blurred image when the auto focus system tracks your chosen subject as you turn the camera away to recompose your shot.

4.Failing to take the time to test the various combinations of focal length settings and aperture settings, for your camera and making note of the combinations with the smallest aperture settings that still result in a sharp picture for each focal length may deprive you of a range of solutions that produce sharper images under a particular set of circumstances than the standard suggestions. Every camera and lens combination is different. Relying on the general guidelines given above is a start on finding the settings that produce clear, sharp images, but your particular camera and lens combination may have additional useful settings. Take photographs pairing various focal lengths with various aperture settings and then compare the sharpness of the images on your computer to see at what settings blurring begins to occur.

5.Failing to test increasingly slower shutter speeds while handholding your camera to discover the slowest shutter speed that you, personally, can use. Some people have steadier hands than others, which enables them to use shutter speeds that are too slow for others. Others with less steady hands may need a faster shutter speed when holding a camera.

6.Failing to take time to practice your photography. It’s not like you have to purchase film and pay to have your photographs developed. So, practice selecting different camera settings, different focal points, different lighting situations, different compositions, and try out all of the automatic and manual settings on your camera. Don’t just try them once and move on the next one. Take 10, 15, 20, or more different shots with each one. Try photographing the same subject using all of the different settings on your camera, and then study and compare the results. 

7.Failing to keep your attention focused on your photography and allowing yourself to become distracted or hurried while taking your shots. Remember that you are attempting to preserve fleeting emotions and fleeting moments. Take the time you need to achieve a well-focused, well-exposed, well-composed photograph.

7 Tips for Shooting Sharp Photographs in Low Light

1.Use your camera’s auto-focus assist lamp. While some cameras use their built-in flash as an auto-focus assist lamp, many have a separate focus assist lamp. Having a separate, infrared auto focus assist lamp is best. The sudden burst of white light from your flash can startle live subjects alerting wildlife subjects to the presence of an intruder and causing them to flee, ruining candid shots of people and pets who are likely to look in the direction of the flash, and annoying people who may dislike having someone sneak up on them with a camera. If your camera lacks a separate infrared assist lamp but has a port where you can plug in an external flash, external flashes with independent infrared focus assist lamps are available. You can also use a flashlight to help your camera focus on a subject that is relatively nearby.

2.Assist your camera’s contrast detection system by focusing on the edge of a brightly lit spot in the image such as a streetlight or the lights or signs from a building might provide. Find a brightly lit spot that is about the same distance from your camera as your chosen subject and select the focus point that is closest to an edge of that spot. As long as your depth of field is wide enough to include your subject and the edge of that brightly lit spot, your subject should be in focus.

3.Take more manual control of your camera’s settings by using shutter priority, aperture priority, or manual mode.

4.Use the lens scale (the numbered ring around your lens) to select the distance between your camera and your subject (the focal length).

5.Use a wide angle lens and a small aperture opening for shooting nightscapes. If you are shooting a tall subject, like a skyscraper, or a broad one like a night landscape or cityscape, set the focal length almost to infinity to allow the greatest leeway for depth of field. As with shooting landscapes in daylight, this setting ensures that everything in the mid-ground and background will be in focus, as will everything except for the very near foreground.

6.Use the Live Focus on your camera’s LCD screen to zoom in on areas of your image to manually focus your camera and to check how sharp the focus is on details of your chosen subject, especially check the eyes of subjects in night portraits. Remember, though, that your camera’s viewfinder, if it has one, focuses more accurately if you have enough light to use it.

7.General suggestions that for selecting shutter speeds, aperture openings, and ISO sensitivity for photographing people in low light include using shutter speeds in the 1/60s to 1/120s for live subjects who are relatively stationary, such as those sitting down at dinner, and shutter speeds in the 1/200s to 1/400s for people who are more active, such as those who are mingling, laughing, or dancing. Once you have selected the slowest usable shutter speed for the situation, open the aperture as wide as the required depth of field will allow. Then, finally, set the ISO sensitivity to 1600 or 3200. Seek for balance between the shutter, aperture, and ISO settings, but if you must choose between a sharply focused photograph that contains a little noise or graininess or a photograph that is less sharp but that contains no noise, choose the settings that give you the sharpest focus.

Conclusions

These tips should speed you on your way toward taking beautiful, clear, sharply focused photographs every time. Auto focus systems are already so good that you can rely on them most of the time to get the camera settings right. That allows you to get creative with interesting, creative compositions – shooting up at a subject from a low angle, shooting down at a subject from a high angle, using macro photography to take unexpected close ups of common objects, or trying out some of the angles and settings that the pros use for their artistic work. Don’t neglect learning and practicing with the settings included with your camera, though, both automatic and manual. The more you experiment and practice, the less intimidating your camera will be, and the less intimidating your camera becomes, the more fun you can have with it. Also, the more you experiment and practice, the more you will learn about what you can do with your camera, and the more you know about what you can do with your camera, the better your pictures will be and the more creative your photography will become. Soon, you could be having the same sort of “I wonder what would happen if I did this” ideas that occur to the pros, and that is the beginning of even more fun.