"You'll have to close the aperture as much as you can and shoot with wider lenses."
Original,
Sounds more like you're looking for a deeper 'Depth of Focus' than DoF. In more technical terms, you're attempting to get the maximum 'hyperfocal distance' from your lens to shoot your scene. Now to be clear, DoF means in layman's terms, 'the amount of image area you get from your lens'. Not 'how far' nor 'how close' your particular lens can focus on a subject.
It's the 'angle of view' to put it another way. So an 18mm lens has a much wider angle of view and greater DoF than a 50mm (which is considered a 'normal' angle lens.) You get above 50mm and your angle of view (DoF) starts narrowing dramatically (i.e. a 50mm lens is much wider than a 300mm.)
Now like Rob mentioned, your 5D's image sensor (or 'image plane') is very large (suitable for theatrical blow-ups.) Know that DoF is dependent on your camera type, aperture and focal distance. So you can easily have the same DoF with a wide-angle lens as a telephoto depending on what and where your subject is. Bottom line; if you want everything in focus, use a traditional video camera with video lenses. Right now you're using a photographic camera with photographic lenses to shoot video. You have to learn and work within the rules of photography to get usable imagery.
Here's a few sites which give good descriptions on what can be a very complex subject:
http://mgreerphoto.blogspot.com/2007/10/hyperfocal-distance.html
http://toothwalker.org/optics/dof.html
http://www.cambridgeincolour.com/tutorials/depth-of-field.htm