Do I have to look into the view finder?

[cyberlord]

Aperture, distance and focal length. The smaller the sensor (or frame of film) the shorter the focal length lens you have to use to get the same field of view as a larger sensor. Hence greater DOF with small sensor cameras.

I'm not sure sensor size affects the DOF. The sensor size just ignores the outer edges of the image that goes through the lens and only records the center of the image. The DOF does not change when you crop an image in post processing. That is all a smaller sensor is doing, cropping the image. It does not change the focal length of the lens where DOF is affected.

Again, I'm not sure. If I'm wrong, someone explain to me if all the sensor is doing is cropping the image, how it can affect the DOF.

Tim

[Erik Stiegler]

The sensor size doesn't directly affect DOF. However, they require shorter focal lengths to get the same field of view.

To get the same field of view as a 35mm lens on a 35mm camera, a camera like the Canon G7 needs a 7mm lens. You get a whole lot more DOF with a 7mm lens than a 35mm lens at the same aperture and focusing distance.