Depth of field (DoF) is dependent upon your aperture setting and your proximity to the subject (how close or far you are from what you are photographing). The lower your aperture setting, the wider the opening in your camera, the more shallow your depth of field will be. But, we also have to factor in proximity to subject. The closer you stand to your subject, and the wider open (lower the number) your aperture is, the more blur you will have around everything but your focal point.
To illustrate, I placed my camera on a tripod and placed it three feet away from my subject. My volunteer this week was Burton. Well, to be perfectly honest, he did not raise his paw to volunteer, so I picked him. I placed him on a bench with a cover and waited for him to settle. I focused on the area just between his nose and his eyes on the bridge of his nose. The first photo, below, has the aperture set at 1.4 (the widest it can go), ISO 100, speed is 1/125.
Leaving the camera in the exact same location, with the focus point still on the bridge of the nose between the nose and eyes, and Burton still quietly laying on the bench, I reset the camera's aperture to 4 (narrows the opening), left the speed at 1/125, and raised the ISO to 400. Here is the result.
If I wanted more of his body in focus, I could change the camera settings again, or I could change the distance between Burton and I, moving farther back, to gain additional areas of focus. Understanding the depth of field capabilities of your lenses is an important factor in planning and setting up your photography work.
A little bit of Burton trivia. He will be nine years old this year and has been deaf since birth. He is very vocal and actually sings for his supper. He was rescued by Another Chance for English Setters and we adopted him at the age of 4 months in 2009. He knows countless hand signals, and reads our body language better than a body language specialist. He loves to play with tennis and chuck-it balls and can leap a good 5 feet in the air to recover a ball on a bounce. He has one lovely blue eye and a bit of blue at the bottom of his light brown eye. I think his ears look like lamb ears.
For more depth of field photos and more discussion, check out this week's blog circle. Start here with Mikahla Dorey of Brackson Photography, Pet & Equine Photographer in Nova Scotia, Canada.