I use my D5100 all the time with manual focus lenses. However as Marty pointed out, the camera now has to be used as a fully manual camera only, with no light meter. The lens will still automatically stop down to whatever aperture you set the lens to, just like your FA. There are times I use a handheld lightmeter, but generally over the many years of using a hand held meter with meterless cameras like a Rollei TLR or a Hassy, I became pretty good at guessing the correct exposure. While I have a few bodies that meter with manual focus lenses, the D5100 allows me to use the few non-AI lenses I have without breaking the camera while still shooting very high resolution photos. You will be amazed at how good those older mf lenses perform on the D5100.

Len

Visit my Nikonians gallery.