DOF and sensor size

We've already talked about how some cameras have smaller sensors than others,…and how sensor size impacts field of view.…But sensor size also has an effect on depth of field.…Smaller sensors inherently have more depth of field than larger sensors.…That means that you cannot achieve as shallow a depth of field with a camera…with a smaller sensor as you can with a camera with a larger sensor.…Here's an image shot with a full frame digital SLR using an f/1.2 lens.…It has extremely shallow depth of field.…

By comparison, here is an image shot with a typical point-and-shoot camera.…While the background is a little soft, it's not nearly as soft as the image from the SLR was.…This is about as shallow as you can hope to go with a point-and-shoot camera.…Now, there are advantages to the inherent deep depth of field of smaller sensors.…If I am shooting with a point-and- shoot camera, I don't have to worry as much…about everything being in focus.…This is great for landscape shooting.…It's great for times when my subject is moving in and out relative to my camera position.…