The answer to this question - Aperture Priority or Shutter Priority? - depends on the effect you'd like to get in your photos. When you use one of these modes, you've taken a big step in taking creative control. Yes, you can set your camera on auto or use one of the camera's basic picture modes, but then you're allowing your camera to make the decisions.
Aperture Priority (Av): This mode enables you to pick the aperture, while the camera automatically selects a corresponding shutter speed to get the best exposure. This is the mode you'll choose when you want to manipulate depth of field. You can set a small aperture (larger f-number, like f/11) for great depth of field when photographing a landscape, or a wide aperture (small f-number, like f/3.5) when you want to get shallow depth of field, as in portraiture.
Shutter Priority (Tv): This mode allows you to select a shutter speed, and the camera chooses a corresponding aperture for best exposure. If you want to blur the motion of a waterfall, you'll want to use a very slow shutter speed (like one second). On the other hand, if you want to freeze the motion of a person running across your field of view, you can pick a fast shutter speed (like 1/500 second).
Quite simply, the Av settings are for times when you want to control depth of field, while the Tv settings are for when you want to control motion effects.
About Author / Instructor / Photographer, Lynne Eodice
The author of Photos That Inspire, Lynne Eodice teaches four excellent online courses for BetterPhoto.com: Photography for the Weekend Warrior, Digital Photography Basics, Photographing Architecture: Around Town or Far Afield and Fundamentals of Great Exposure. She is also the former Feature Editor for Petersen’s PHOTOgraphic.
A native of Southern California, Lynne was educated at Pasadena City College and Cal Poly Pomona. Her love of photography began after her husband gave her a 35mm SLR as an anniversary gift. She began her career as a feature writer & photographer for local newspapers that included Pasadena Weekly and The Herald Tribune.
Besides having articles and photos published regularly in PHOTOgraphic, she has contributed to Rangefinder, Digital Photographer and California Tour & Travel, as well as PHOTOgraphic’s Buyer’s Guide, Big Book of Photography and Family Photo magazines. Her images have appeared in a popular instructional book called The Complete Idiot’s Guide to Photography, and she has marketed her stock photos through Index Stock Imagery in New York.
Lynne has exhibited her fine-art scenic photography at Kolb Studio and the visitor’s center at Grand Canyon National Park in Arizona, at Occidental College in Eagle Rock, California, and at venues throughout the San Gabriel Valley. In addition, she has taught many classes, seminars and workshops.
In the fall of 2007, she was honored as one of the Women Achievers in the San Gabriel Valley in Business Life magazine.
Lynne currently lives with her husband, Dennis and their dog, Chiquita in Altadena, California.