So your photos are out of focus… Wanna know why?

You have gone out and purchased a new camera and lens combo and you get it home and your photos are not sharp. You’re disappointed because you spent a lot of money to get a good setup and it just doesn’t work…

Of course there are a few circumstances where the camera does have issues that need repaired or adjustment. Many times though, it has more to do with how you’re using the camera.

Blurry pictures come from three main areas; each with a couple of sub points each. The three areas are: The movement, optics and camera settings.

Movement

Lets start with movement. There are generally two types of blurs that happen due to movement: you subject moves or you move. In both cases, they are the result of having too slow of a shutter speed. For the moving subject, sometimes that blur is desirable (a running stream of water, a moving athlete, the propellers on an airplane or helicopter. But for your average photo, subject movement is generally considered bad.

The second and more common source of movement is you. Various people are more steady or less steady than others. But unless you are using a tripod or some other steady surface and a remote release, you risk putting your movements (breathing, shaking or simply the act of pushing down on the shutter) into the photo.

This is generally managed by keeping your shutter speeds high enough to take your movement out. The rule of thumb is your shutter speed should be higher than 1 / lens focal length in millimeters. Ergo, a 50mm lens needs a minimum 1/50th of a second for the average person to safely handhold. Using whole shutter speed numbers, that mean’s 1/60th of a second. But wait.. There is more. Most of our digtal cameras have smaller sensors than the 35mm film the lens was designed for, which gives them an effective longer focal length. On Nikon DX based bodies for instance, that lens is effectivaly 1.5x longer. Your 50mm lens on a DX body is really a 75mm lens in this equation, which means you really need a minimum of 1/125th of a second to hand hold it.

Motion blur typically shows up as blur moving in one direction (up and down, sideways or more commonly at a diagonal).

Optics

This has to do with the lens itself. First, it could simply be out of focus. There are several camera settings we will talk about later that covers some of this. It could be out of focus due to imperfections in the camera body. It could be out of focus due to fingerprints, dust, or other things obstructing the light path to the camera’s sensor. Finally it could be a lack of “Depth of Field”.

The cheaper the lens, the poorer quality the glass is. Well that’s not quite true. A 50mm F1.8 lens is only around $100 and can be the sharpest lens you own. This has more to do with Zoom lenses, which require a lot of optical mischief to make work. But still a $100 50mm F1.8 typically is not as sharp as a $400 50mm F1.4 lens. Price matters.

With our zoom lenses, we are sometimes drawn into the fact that I can get an 18mm-200mm in one lens covering very wide angle to fairly long telephoto. Buying one of these super zooms seems like a good deal since one lens can do everything. But these lenses to pull off their magic are prone to distortion. It would be too much to talk about the different distortions, but they include barrel, pincushion, vignetting, chromatic aborations, etc. They all can add up to less than sharp photos. These super zooms also are sold among the lower quality lenses. Professional photographers pay $1500+ for pro F2.8 zoom lenses for a reason. They are optically sharper, cover less range and produce better photos. Zoom lenses are typically built with multiple lenses inside. Sometimes through abuse, these lenses can get out of alignment and affect your focus.

The most common optical problem with focus though is “Depth of Field” and a photographer not understanding how it works. It’s too much to go into detail in this post, but the closer you are to a subject and the wider open your lens, the less of the photo that will be in focus. With the right lens and F-Stop combination, the amount of the photo in focus can be under a half inch. It’s important to be a good photographer that you learn Depth of Field, its cause and effects and what properties of the lens like focal length, distance, and F-stop impact the amout of the scene that will be in focus.

Camera Settings

There are some physical things in the camera body that will cause photos to be out of focus. Some are a bit more common than others, but you need to be aware of them.

Your camera’s autofocus system depends on contrast to focus. Try using your AF against a flat one-color wall. Your camera will likely not be able to focus, but aim it a light switch where we have some contrast and it will snap right into focus. Knowing how your AF sensors work is critical to helping you get sharp photos. So make sure your active AF point is aimed at something with some lines in it. The more contrasty the better.

Frequently the sensors are in the base of the camera under the mirror and part of the light passes through the mirror to a secondary mirror behind the main mirror bouncing the light to the bottom of the shutter box. What you see in the viewfinder may not be the actual sensors but a reasonable estimate as to where they really are relative to the overall scene.

If your mirror is just the tiniest bit out of alignment, or your mount is bent slightly you might suffer something called Back Focus or Front Focus where the light isn’t focusing in the right spot (well the camera is telling the lens the wrong information.) There are tests you can perform to see if this is the case. Your camera will need repaired if this is the case, which should be covered by warranty if it’s a new camera.

Your AF points could be smaller than the box you see in the viewfinder. They can also be slightly out of the box. Some sensors can work well with horizontal lines, others vertical and some of the sensors are cross type, which work with both vertical and horizontal lines.

This can be related to alignment problems as mentioned above, or it could be a simple case that they just don’t line up. You can learn where the AF points really are and what type and adjust your shooting style accordingly.

Most cameras require a lens opening of F5.6 or faster for autofocus to detect enough contrast to work. So as light levels drop or contrast fades away, the AF system becomes less accurate (tends to hunt for focus.)

Cameras have different focus priorities. I’m not that up on the Canon’s but they are not that different than the Nikons. Your focus priority can be typically one of two things: Single Servo (and I apologize for all Nikon terms) or Continuous Servo. In Single Servo mode, the camera will require it to believe that the photo is in focus before it will take the photo (more on that in a bit). In Continuous servo mode, close enough counts. Basically it take the photo when you push the trigger in focus or not. Typically the camera is in the process of focusing and will be pretty close when it actually fires. I shoot in CS mode all the time because I want the photo I’m taking, not one in a few seconds when camera thinks its in focus. If you’re in CS mode, you will have some AF misses or slightly out of focus pics.

Camera’s have different focus modes: Some track your subject with a single moving AF point, others use a cluster of points to try and determine the focus, sometimes it uses all the AF sensors and locks onto the closest thing that’s in focus. Depending on the focus mode you’re in and say you’re trying to AF on a close up portrait of someone and you’re focusing on the eyes, with the camera being in mode where it focuses on the closest thing that will tend to be the nose.

Our camera’s in-camera processing also applies several filters to fix things by blurring the photo. Ideally the image processing of the camera should produce a sharp detailed photo and the lower ISO settings. But as light levels drop and your ISO setting kicks up, your camera can get more aggressive with High ISO noise removal (most cameras let you set the aggressiveness). If you have Auto ISO on, your ISO’s may be creeping up into the high ranges and the noise removal can be softening the photos too.

Another setting is your camera’s sharpness setting. Just as the name suggests it affects the sharpness of your photos. For photographer’s shooting RAW based images, in-camera settings like Sharpness are not rendered, but instead the settings are recorded and your RAW processing software may apply the sharpness setting one the photo is on your computer.

The sharpness setting can typically be OFF, Low, Medium and High sharpening. In digital photography, sharpening should be the last step before printing. Thus many professional photographers turn off in-camera sharpening and save that task for post-production, which will result in, blurry out of camera photos. On the other hand, cranking up the sharpening camera may make the photos look better out of camera but photos can become too sharp and you loose some ability to control the quality of the image during post-processing.

There are many factors that go into producing sharp images. Any one of them can affect the seasoned pro as well as the upstart photographer. The more you learn your equipment and its limits and qualities, the better your photos will be.