It is my understanding that as the photosites on a sensor become smaller diffraction becomes an issue. I believe Thom Hogan recommends f/13 as the smallest f-stop you should use with a D200 (and f/11 on a D300). Anything physically smaller and sharpness begins to fall off. For those of you using a D3 do you find that you can use the smaller apertures, say f/16 and f/22, without losing sharpness? If so would the D700 be a good camera to use for macro-photography?