F-Stop Reminders
Understanding F-stops: Aperture Priority
By Rob Sheppard
I rarely shoot anything but aperture priority. Occasionally I shoot manual when I need a specific sort of control (such as controlling ambient light with flash). Many sports shooters use aperture priority, too. Here’s how I use it:
Depth of field — choose an aperture for appropriate depth of field. This doesn’t mean automatically choosing the smallest apertures, such as f/16. I will use f/16 when I really need deep depth of field, but I will shoot f/8-f/11 for distant scenes where depth of field is unaffected by f-stop; f/8-f/11 tend to be the sharpest parts of most lenses. I will choose wide apertures such as f/2.8-f/4 for selective focus effects to keep subject sharp and background soft. I will typically shoot close ups at f/5.6-f/8 to gain some depth of field, but not too much (since it is difficult to get close-up backgrounds sharp anyway, I would prefer them more out of focus).
Action - choose the wide f-stops. A pro technique is to set the lens at its widest or maximum aperture, such as f/2.8-f/4. You are looking for the smallest number you can set with your lens. Then with aperture priority, you guarantee that you always will shoot with the fastest shutter speed possible for the conditions. You cannot do that with shutter speed priority. The wild turkey seen here, for example, was shot with aperture priority, max aperture, so that as the bird moved through different levels of light, I was always getting the fastest shutter speed possible for the conditions. The only time I might consider shutter speed priority would be if I wanted to use a very specific shutter speed, such as a slow speed for a water blur.
Some photographers are very comfortable with manual exposure, which works fine, but some photographers use it because they think they “should” in order to be a “real” photographer. I used to feel that way many years ago. But honestly, modern auto exposure systems are so good that they are faster, more convenient, and can be just as accurate. They certainly require a lot less thought about technology! And with digital, you can quickly see if your exposure is right or not by using the LCD with highlight warnings and histogram.
More details: Become a master of exposure – and aperture – with Rob Sheppard’s outstanding online photography workshop: The Magic of F-stops: Choosing the Right Aperture. Also check out BetterPhoto.com’s other digital photography online courses.
