Are you using a defocus filter or something? In real life in cameras (eyes) there’s like a hole trough which the light enters before it hits the sensor/film. I think they call it “aperture” or something. Anyway, if this hole thingy is big, than if you take a picture of someone, everything in foreground and background will be very blurred. However if the hole is small all elements will stay in focus.
Now you don’t get this in blender (and most 3D applications) by default. You have to use a filter called “Defocus” in the compositing window to achieve “depth of field”. Select “Nodes” from the menu in the lower left corner of the 3d window and check if there’s something like that in use.
Please post a render if you can, it will make it much easier for others to understand the problem.