For certain subjects, and specific types of macro photography, manual focus is the best way to go when utilizing a macro lens. In fact, the large majority of macro lenses available today are manual focus only lenses. Both Canon and Nikon offer several high-end auto-focus (AF) versions that offer outstanding performance in regards to their AF systems.
When composing a typical macro photograph, we are generally set to “One-Shot” mode, and set the AF point to the desired position within the frame. What about when we have a live subject buzzing around the frame, or a spider who is frantically trying to elude being “captured” by that shiny round object in its face? Well, there is a significantly better way to deal with these less than cooperative moving subjects. One day it dawned on me, why not utilize the same method I use for wildlife photography? Assuming you have an AF capable macro lens, you can set you Canon camera to A1 Servo AF (Continuous focus on the Nikons), and even set your drive mode to low-speed or high-speed drive, allowing you to potentially fire off multiple exposures of your pesky subject. By using A1 Servo or Continuous AF, the system tracks the subject as long as the selected AF points are kept on the subject. This may take some additional practice, as using a macro lens magnifies the subject, and things can get a bit touchy.
Depending on the camera you have, you may be able to go into the custom-function menu and adjust the AF sensitivity in regards to how quickly the AF system moves OFF of the subject and starts hunting for a new one if you suddenly lose your subject under the AF points. If you set this adjustment to be very slow, it will be forgiving in a sense, and allow you another second or so to regain your position on the subject without your AF system zooming out to the background. Also: I HIGHLY suggest going into the
custom-function menus and setting your camera to have the AF activated by the “AF-ON” button on the rear of the camera vs. depressing the shutter button half-way. When using A1 Servo, it is nearly impossible to hold the shutter button halfway for extended periods while tracking a subject and not releasing the shutter. It is much easier to hold the AF-ON button down, and have the shutter button simply act as a shutter release for which it is intended. An added benefit of setting your camera up this way is that it allows you to simply hit the AF-ON button and release it to lock focus. This is the same as switching back to One Shot mode, but saves you the step of actually having to switch back and forth between A1 Servo and One-Shot modes. When I am photographing wildlife, I never switch modes regardless of whether I am photographing a still subject, or flying birds; the drive mode always stays on A1 Servo. I am always ready for anything by utilizing these settings.
So, to “up” your macro photography success rate a few notches, try utilizing A1 Servo or Continuous AF with the settings I recommend. You may find that you like them so much, that you will never look back!