This set of pictures was taken with an extreme Depth Of Field (f/50, f/100) by using a small pinhole (purchased from http://www.lenoxlaser.com/) mounted in a lens cap front of the lens.

With the lens set to manual, and wide open, the following applies:

With the 1mm laser cut pinhole, the f/# = the focal length of the lens.
In these cases my 50mm f/50

With the 0.5mm (500um) laser cut pinhole, the f# = twice the focal length of the lens.
In these cases my 50mm at f/100

Of course, at these extreme DOF you get some softening from the diffraction of the small pin hole, but this is minimal if not taken to too much of an extreme, and can be "fixed" with many sharpening programs. (I used Focus Magic on the flower shots, but not on the guitar or beach scene.)

Long time exposures are required - so a good tripod is a must.

I started these experiments with holes poked an aluminum foil, which works fine. I went with these because I wanted a more accurate measure of the size (thus fstop) and something more robust for the field. Shape of hole, cenetering of hole and such are not critical, but it MUST be in a thin material. A thick material will behave more like a tunnel than a hole and will vignette.