Zoom Vs Depth Of Field
When you want more depth of field, you can:
1) stop down the aperture (make the f-number higher)
2) get closer and magnify less, if possible
Getting closer does not really help, if you are shooting the same object size then the DOF stays pretty constant if you go to a wider focal length but move closer in. The first point is right smaller apertures will get you better DOF, but may lower shutter speed enough to require a tripod or high ISO settings. The other option is to shoot a wider scene (as mentioned in 2). At the same distance a shorter focal length will give better depth of field. Third option is to get a camera with a smaller sensor so that a shorter focal length will give you the same object size. Post cropping the wider scene will also give you more DOF but at the cost of image detail for the same enlargement size.