To fill the frame with the small red eye tree frog, I used a 50mm macro lens plus an extension tube. The depth of field, which encompasses the entire frog and the stem on which it was resting, is the result of using a lens aperture of f/32. Yes, the smallest apertures degrade image quality especially at the edges, but shallow depth of field doesn't reveal all of the intriguing detail and texture of small subjects. Photography is all about compromise. In this case, I opted for slightly less quality in exchange for more sharpness throughout the image. I know that sounds odd -- contradictary, actually -- but lack of focus (i.e. shallow DOF) is much more of a degradation than what happens when f/32 is used.
I took this shot last week during my semi-annual frog and reptile workshop in St. Louis. The next one will be in September.