This is the way I can achieve greater depth of field in macro images. I Take a series of images of the same subject and adjust the plane from near to far. I can set the lens to f5.6 which is the setting with the least diffraction and greatest sharpness. Then I use Photoshop CS4 to assemble the images. When it is finished the final image shows everything in focus.
This shows the range of depth of focus used.