Depth of Field and macro

When photographing small subjects, pay special attention to depth of field.  As you move in close -- even to a venomous snake like this eyelash viper in Costa Rica -- DOF becomes very shallow.  I used a 70-200mm lens here with an extension tube, essentially turning this medium zoom into a telephoto macro, and that meant that the depth of focus was minimal.  We can accept out of focus backgrounds, but soft foregrounds are visually annoying and unattractive.  Therefore, use a small enough lens aperture to make the picture successful.  Here I used f/16.  The entire front of the snake, including the all-important head and eye, are sharp as they should be.