Only a thin band on the Z axis is rendered in sharp focus.

• A. Shallow Depth of Field
• B. Deep Depth of Field
• C. F-stop
• D. Aperture

Answer: (A)

The main idea here is how depth of field controls what distances from the camera stay sharp. If only a thin band along the Z axis is in sharp focus, you’re seeing shallow depth of field—the plane of focus is very narrow, so objects in front of and behind that plane blur quickly.

This effect shows up when the lens aperture is wide (a low f-number), which reduces the zone of acceptable sharpness. You can also get it by using a longer focal length or getting closer to the subject. In contrast, deep depth of field would keep a larger range of distances in focus, from near to far.

F-stop and aperture are the controls that produce this effect, but they describe the tool rather than the result itself.