Shoot in AV Mode, so the shutterspeed will be automatily adjusted. The hood has now effect. Only the sensor size, the focal lengh, the aperture and the distance to your object will have effect to your DOF
I dont know if you noticed the button on the right side of your lens mount. This is to control the dof.
Well that button is not to control, is to Preview the DOF, when you press it will stop down the lens to the apperture you have set, so you can see what will be in focus.