The Blurry Photo Problem
Tips to help you fix the fuzz in your photos
It happens to everyone. You take a great photo of a great event. You preview the image on your computer and disappointment sets in. The entire photo looks blurry.
What is causing these blurry digital photographs? There are three common culprits with digital cameras: long focal lengths, slow shutter speeds and wide apertures.
Focal Length and Camera Shake
When you use a lens with a long focal length, camera shake becomes more pronounced. It's similar to climbing a ladder. When you're on the bottom rungs, the ladder is stable and doesn't move around much. As you climb the ladder, it becomes increasingly unstable.
The same thing happens with your lens. When you have it set to wide angle (28mm) you're at the bottom of the ladder. When you look through the camera viewfinder, you should not see a lot of shake — the image should appear stable.
When you zoom in on a subject and extend the lens, it's like climbing to the top of the ladder. At a long focal length (200 to 300mm) you should see a slight jiggling when you look through the camera viewfinder.
You can use a long focal length, so long as you set your shutter speed fast enough so that the camera shake is canceled out. The general rule of thumb is that you should not use a shutter speed slower than 1 over the focal length of the lens when you are holding the camera in your hands.
At 28mm, you should be able to get a clear photo with a shutter speed of 1/30 of a second. At 200mm, you have to increase the shutter speed to 1/250 of a second to get a clear photo. At 600mm, you had better be using a shutter speed of 1/700 of a second.
If there is not enough light to support these shutter speeds, then you have two options. Option one: purchase a camera that has image stabilization (IS). Image stabilization is a mechanism within the lens that prevents shake even at long focal lengths.
Option two: place the camera on a tripod, which also eliminates camera shake.
Slow Shutter Speeds
Slow shutter speeds will cause blurry photos every time. You might wind up with a slow shutter speed and be unaware of it if you have your camera set to aperture priority mode. In aperture priority mode, you select the aperture and the camera determines the appropriate shutter speed to get a good exposure.
Say you have your camera set with a focal length of 100mm, an aperture of f8.0 and a shutter speed of 1/125. You are taking photos in bright daylight, and with these settings the photos will appear clear.
Now the sun dips behind a cloud. Your focal length is still 100mm, your aperture is f8.0, but the camera has adjusted the shutter speed to 1/60 for the correct exposure. Now your photo will appear blurry.
If all of these numbers seem overly complicated, here's the general rule I use: try to avoid shutter speeds slower than 1/125 of a second when holding the camera by hand. This covers all the focal lengths from 28 to 125, which is a pretty good range (a 3x zoom typically goes from 35 to 105mm).
When you use a wide aperture setting on your camera (f2.8 for example), you significantly reduce your depth of field. Sometimes, you can reduce the depth of field so much that the object you focus on appears clear, but another object less than an inch behind it is fuzzy.
Think of it this way: you take a photo of a giraffe with an aperture of f2.8. The camera chooses to focus on the end of the giraffe's nose. Due to the extrememly shallow depth of field, the eyes of the giraffe appear blurry.
This problem is especially significant when you use a long focal length lens. As you increase your focal length, you further reduce the depth of field. So a long focal length and wide aperture don't give you a lot of depth of field to work with.
If you are using a compact camera, you should not see this effect very much. The reason is that f2.8 on a compact camera does not create the same visual effect as a digital SLR lens set to f2.8. You won't see the same shallow depth of field with the compact camera as you will with the digital SLR.
The solution to this problem is to use a smaller aperture (around f8.0), especially when you use a lens with a long focal length.
Here is a quick summary of the issues and solutions for getting sharper photographs.
|Camera shake with a long focal length||
|Shutter speed is too slow||
|Wide aperture creates a shallow depth of field||