Autofocus is taken for granted. When I think back to some of the great sports and action shots made before it was introduced, I appreciate and respect the photographer’s talent. Each was a master at their craft. When autofocus was implemented into SLRs, the landscape began to change. Crude and unreliable at first, the technology kept getting better until it was a given that autofocus was here to stay. It keeps getting better, faster, more accurate, and more reliable. For this I am extremely grateful. My number of keepers has gone up exponentially. So even with all the improvements, why is it that photographers still get images that are not sharp? Hopefully the following tips will net you sharper photos.
Select The Proper Focus Point: When I teach a workshop or lead one of my photo tours, one of the biggest “Aha’s” I hear is, “I can move the focus sensor to place it where I want?” If the active focus sensor is aimed at the background and your subjects are only a few feet in front of you, they will not be sharp. To activate an autofocus sensor, press half way down on the shutter. Then press or turn the command dial to place the focus point over the subject. This ensures the lens sees what plane you want sharp.
Single vs Continuous: If the subject does not move, activate “single shot” autofocus. You will hear a confirmation beep when the plane at which you place the focus sensor is sharp. Landscapes, architecture, posed portraits, interiors are all examples of subjects that work better using single shot. Continuous should be used when the subject moves, especially if the path is erratic. As always, the sensor should be placed over the moving subject. The beauty of continuous mode is the camera predicts the movement of the subject and adjusts for variations at the time the shutter opens.
Work Within the Limitations of Your Gear: One reason photographers get frustrated with their less than sharp photographs is they expect more out of their equipment than what it can produce. Many autofocus advancements have been made, but if you exceed its capabilities, it can’t deliver. I photograph a lot of birds in flight and by no means do I expect every image be sharp especially if the bird flies directly at me. Slow lenses and entry level cameras can’t equal the capabilities of pro equipment. And given the situation, even the top pro equipment can’t net a tack sharp image every time the shutter is pressed.
In the three images that accompany the article, I used different focusing techniques to acquire a sharp photo:
A - In the first I used Single Focus. In that it’s a basic scenic with no movement and everything out in the distance, I stopped my lens down to f11 as it’s one of the sharpest apertures on my lens. I used the center focus point and everything in the photo was rendered sharp.
b) For the photo of the sandhill crane flying in front of the rainbow, I used Continuous autofocus (it’s a Nikon function / Canon equivalent is AI autofocus). I locked onto the bird using the center AF point and let the focus automatically transfer to a focus point on the right so the bird had space in which to fly. I set the focus to 3D Dynamic AF as this mode enables the camera to transfer AF points while panning with the subject.
c) The white feathers of the great egret at dawn lacked contrast. So did the water in which it was standing. In that the camera had trouble acquiring focus given the lack of contrast in the two above sections, I placed the focus sensor on its beak. Placing it on the beak provided my system a point of contrast and ensured the focus would be accurate.
Visit www.russburdenphotography.com for information about his nature photography tours.