There are four major factors that cause blurry photos, and all four of them are important to remember for every picture you take. Here, I will explain how to avoid each type of blur, or minimize them as much as possible, in your photography. Specifically, the four sources of blurry photos are motion (from the camera or subject), out-of-focus blur, diffraction, and lens aberrations.
Motion Blur and Camera Shake
Perhaps the single biggest cause of blurry photos is motion blur, due to your subject – or your camera – moving too much while the photo is being taken. Motion blur only appears when something in your photo moves across multiple pixels during your exposure.
Although this type of blur is strongly related to the speed of objects in your photo, or how shaky your camera is, those aren’t the only factors that matter. Your shutter speed is also vitally important. With a fast enough exposure, you can photograph almost anything with sharp results. Even if you’re photographing a bird or animal moving quickly, just use a 1/1000 or 1/2000 second shutter speed, and you won’t get much blur at all:
This applies equally to handheld blur. No one can handhold a camera perfectly still, but the movement caused by your hands is pretty easy to deal with. Just follow the handhold rule to be sure you’re using a fast enough shutter speed. Err on the side of caution. Personally, I prefer “1/(2 × focal length)” instead of “1/(focal length)” for handholding my camera, unless I have vibration reduction turned on.
Technically, all you need to do to eliminate motion blur (whether from your subject or from camera shake) is to use a fast enough shutter speed. A 1/8000 second exposure will get rid of motion blur for almost any photo. The only issue – and it’s a big one – is that fast shutter speeds lead to darker photos, and getting a bright enough photo is one of the fundamental problems of photography. If you’re planning to use an ultra-fast shutter speed, you better have some way to compensate and get a bright photo anyway.
So, the ideal situation is to use a shutter speed that is just barely fast enough to eliminate motion blur, or capture such a small amount that it’s irrelevant. Finding the sweet spot takes some serious practice. Maybe the ideal shutter speed for a portrait photo is 1/100 second, 1/500 for a sports scene, 1/2000 for a bird in flight, and so on. The main exception is when you’re photographing a nonmoving scene from a sturdy tripod, in which case you can use pretty much any shutter speed without a problem. The same is true if you specifically want part of your photo to be blurry for effect.
However, even if you’re using a tripod and your subject isn’t moving, you still might end up with some camera shake. That’s because the camera itself has moving parts, especially the mirror on a DSLR and the shutter curtain on most cameras. At certain shutter speeds, these will cause vibrations you can see in your photos. The danger range is 1/2 second to 1/50 second, and it is more likely to be visible with telephoto lenses.
You can minimize these sources of blur by using electronic front-curtain shutter (if your camera has it) as well as mirror lockup mode (or Exposure Delay mode on Nikon cameras). You might also consider a remote shutter release. We have specific articles on shutter shock and taking sharp photos from a tripod that explain these techniques in more detail.
Lastly, there is one unrelated way to minimize motion blur in a photo: Light the image entirely with a flash. The duration of most flashes is very quick, freezing the motion even of extremely fast subjects like hummingbirds. But you can’t light every subject entirely with flash, so this is far from a perfect fix.
The other biggest cause of blur in photography is out-of-focus blur. This one comes in a couple different shapes and forms.
On one hand, the most obvious example of out-of-focus blur is simply when you miss focus. Either you focused slightly too close or too far, and the end result is that your subject isn’t perfectly sharp. In the worst cases, your subject may be wildly out of focus because your autofocus system couldn’t lock onto anything.
The key to avoiding this type of blur is to take your time in the field and make sure you’ve focused on the right subject. If you have the time, magnify live view to double check that your focus is perfect – say, on your subject’s eyes rather than their nose. If you’re photographing fast-moving subjects like sports, the key is practice above all else. Get to know exactly how your autofocus system behaves, its strengths and weaknesses, and how to lock onto your subject every time.