In Focus, Out of Focus, Autofocus
Camera Corner report by Dirck Halstead
Looking back over some of my old photographs, shot while working for the local newspaper, in my teens, I was struck by how sharp my pictures are. 

The reason they're so sharp--I was using a 4x5 Speed Graphic. Sure, it had a range finder mounted on the side, if I wanted to use it. And for seeing what the picture would really look like, I could always view it through the ground glass on the back of the camera, which displayed the entire image--even though it was upside down. But, the main reason why I could nail those shots was because the first lesson I had to learn, as a budding photojournalist, was to evaluate distance. I learned, within a fraction of an inch, what a six foot, ten foot and fifteen foot shot looked like. I would then calculate the distance, set the focus track to that point, and voila, I couldn't miss. 

Of course, some of was is due to the fact that the lenses on those Graphics were generally 127 or 135mm lenses, which would be the equivalent of a normal lens on a 35mm camera, with lots of depth, especially when you shot with a flash at f/8. 

Then came 35mm cameras, with lots of long, fast lenses. The little viewing screen, which was none too bright, coupled with shallow depth of field, suddenly made critical focusing a major part of the picture-taking effort. In low-light situations, especially in sports, the eye fatigue from long periods of focusing, would wear down even the best photographers. 

Then, along came "autofocus," just in time for a lot of us. In the past few years, autofocus has been added to video cameras. So, why are there still so many out-of-focus pictures being taken? 

The answer lies in understanding that although these lenses can be a great help, there are still some basic limitations to be considered. 

The autofocus lens, as advanced as the industry can make it, still does not have a brain. Even with such fancy frills as "predictive autofocus," the lens alone will never grasp what, in that field of view, you really want to focus on. The "target" the lens focuses on is based on your preselection of an area of the picture that you want to focus on. Provided the focus is then locked-in, the picture should be sharp. However, the factor providing the major clue to the autofocus machinery is contrast. The lens loves different shapes and relative areas of brightness. If you want to check this, just autofocus on a person in dim light, then turn on a light behind them. The lens will most often shift focus to the new light source. 

Even in the best light and contrast, an autofocus lens will often "get bored" with staying focused on a given area. It will want to find something else to focus on, and start to hunt for a new focus point. This feature can be especially disconcerting in video, when a nice, sharp "talking head" suddenly goes soft in the middle of a great sound bite. 

Professional television cameramen will rarely, if ever, use autofocus. As they say, "it can bite you in the ass, big time." 

However, there is no doubt that autofocus, either on a still or video camera, can make your life a lot easier, and increase your batting average for sharp shots. Here are some basic rules to follow: 

1.) Do not use a shutter-release autofocus button for stills - with the exception of sports photographers, who can't afford a second of delay between focus and shooting. Instead, transfer the autofocus function to the buttons or dials located elsewhere on the camera. This permits you to focus quickly on a specified area of the picture. Remember, though, the minute you remove your finger pressure, it locks the focus on the desired subject. In video, if the camera has an autofocus lens, the proper procedure is to leave the lens in manual focus, and use the "quick focus" button on the lens to assist your eye. 

2.) The best use of the autofocus lens is in photographing a moving subject approaching the camera. As long as the action continues towards the lens, the lens will do a far better job of focusing than your eye. For example: the President is reviewing a line of troops, and the photographer is shooting at the end of the troop line. 

3.) What the autofocus lens has trouble with, on the other hand, is lateral movement - crossing the axis of the picture. In this case, your eye will generally do a better job. 

4.) In low-light situations, beware of bright objects in the background. During my initial use of an autofocus camera (which happened to be a Minolta, first to put out an autofocus system), I was photographing the visit to Ronald Reagan by George Bush, after Bush won the Presidency. The photo-op took place in Reagan's Los Angeles office. Instead of focusing on the two men, the camera liked the lamp sitting behind Reagan better, and the picture was unusable. 

5.) Do not use autofocus on still subjects. And never use autofocus on a video camera for an interview. 

The judicious use of autofocus can save wear and tear on your eyes, and help you concentrate on the more basic elements of picture taking. But the lenses must be used with care and thought. 


Reviews of new equipment appearing in the Camera Corner of THE DIGITAL JOURNALIST are solely the opinion of the author. There is no compensation or pressure by the manufacturers considered in the evaluation of the products reviewed on these pages.


Contents PageCamera Corner
Contents Editorials The Platypus Links Copyright
Portfolios Camera Corner War Stories  Dirck's Gallery Comments
Issue Archives Columns Forums Mailing List E-mail The DJ
This site is sponsored and powered by Hewlett Packard