Depth of Field in Aperture-Priority Mode during Dog Photography
Manipulating your depth of field is a fantastic way to home in on specific details of your image and draw the viewer’s eye exactly where you want it—to your dog's expressive eyes or wagging tail.
70mm, 0.4 sec., f/18, 250 70mm, 1/125 sec., f/2.8, 250
Here, you see the same image side by side, but each image tells a very different story. The photo on the left was taken with a very small aperture (f/18) and would likely be described as a woman and her dog enjoying a view of the distant city.
This photo has great depth of field, which keeps the subjects and the distant view all in focus. Equal weight is given to the subjects and the background; neither really stands out from the other.
Conversely, the photo on the right was taken with a very wide aperture (f/2.8) and would likely be described as a woman and her dog bonding. This photo has very shallow depth of field, which keeps the subjects in focus but blurs the view of the city. The effect that your aperture has on your final image is dramatic, to say the least!
When working with a very small aperture, you let in very little light, which may result in you needing an extremely slow shutter speed. The image on the left was photographed using a tripod because it called for such a slow (0.4 second) shutter speed. Because the photo’s subjects were sitting still, a slow shutter speed was okay to use.
Use aperture-priority (AV) mode when you want to make deliberate decisions about the depth of field in your final image. To work in AV mode, simply set the mode dial on your digital SLR to AV. Then you can freely flip through your f-stop settings until you land on the f-stop you want.
The exact dial or button you use to change your f-stop varies from camera to camera, so check your manual if you’re unsure of how to do this.
When working in AV mode and shooting with a shallow depth of field (a smaller f-stop number), try to accurately focus on the exact area that you want in focus because much of the shot consists of bokeh, the purposely out-of-focus areas that are rendered as a soft, creamy blur.