Four Tips For Keeping Your Images Sharp!
You've done it! You got the image of the year!
You captured the game-winning slap shot zipping past the goalie's glove, you got the bride smashing wedding cake in the hapless groom's face, the priceless expression of your child opening that special gift, the Bald Eagle snatching the fish from the water. It's a spectacular shot, and it's going straight into your portfolio.
And then you see it up close. It's soft. It's a disaster. And it's really heartbreaking.
Most of us who shoot in situations where we can't rigidly control the subject, the lighting and the environment, have faced this massive disappointment at some point.
In this case, my alligator's eyes are just a bit soft, ruining an otherwise good shot.
Not to worry. I'll get another crack at him during my Florida Bird Photo Tour coming up in a few weeks!
Here are the four primary causes of soft images, and some tips on how to avoid them.
1. Focus Points: It sounds obvious, but if you focus on the "wrong thing", chances are pretty good that the "right thing" will be out of focus. In other words, you'll need to make sure that whatever you want to be sharply in focus is accurately focused on. My alligator is a prime example, but when shooting any large-aperture lens, be aware of this threat, due to the shallow depth of field.
Most modern cameras give you the ability to select any single focus point, a small group of focus points or to activate them all at once. By carefully managing this selection, you'll greatly increase the chance of the camera focusing on the right subject.
2. Camera Shake: If your shutter speed is too slow, any movement of the camera, even imperceptible movement, will blur your image. Here's a guideline that will help you to keep your shutter speed high enough to avoid this problem.
For a hand-held image shot with a non-stabilized lens, your shutter speed should "match" the focal length of the lens. Here's how it works in practice:
Let's say you're shooting hand-held with a non-stabilized 200mm lens. Your shutter speed should be 1/200th second, or faster.
But what if that lens has image stabilization? Most lenses claim about two f-stops of image stabilization, though some claim more. Let's say that your lens claims two f-stops of stabilization.
Remembering that one f-stop represents a change in the amount of light by a factor of two, that means that you can divide that 200 in half twice. So with the stabilization on, the minimum shutter speed required to prevent blur from camera shake drops from 1/200th second minimum to 1/50th second.
That's why those image stabilization lenses have saved countless images from the recycle bin!
3. Subject Movement: Simple enough—if your subject moves too fast, you'll get a blurry subject. Now, there are times when you may want to use blur creatively, but for the sake of this discussion, we'll assume that you don't.
The minimum shutter speed required to freeze motion varies greatly with the subject, but here's a rough guideline. For people at rest, 1/60th second. For people in moderate motion, 1/125th. For sports, 1/250th.
For this image of a Great Egret's courtship display, I shot at 1/500th second, freezing his motion completely. I used the Canon 600mm F/4 L IS lens, stopped down a bit to F/6.3.
4. The Lens: Lenses are never their sharpest when at either extreme of their aperture setting. I have seen some of kit lenses produce astonishingly soft images at the smallest aperture setting. Here is an example:
Compare these two images shot by a student during one of my photography classes, both shot with the Canon EF-S 18-55mm kit lens, as we were doing a depth-of-field exercise. And the camera was focused on the sign for both images—only the aperture and shutter speed were changed.
Unfortunately, there is a direct relationship between the cost of the lens and the sharpness it is able to produce. (Sorry. It just works out that way.)
Individual lenses will be sharpest at different apertures, and the best way to find that sweet spot is to test them. But if you use a mid-range aperture like F/8, you'll be a lot closer to it than at F/1.8 or F/32.
By understanding these four most common causes of soft images, you'll be in a better position to create the best photographs possible. And you'll avoid the disaster of that "almost" sharp image that will just break your heart!