I think it is OK handheld, but certainly depth of field is so limited that focus can't be guaranteed. Here is one from today showing the area in focus is less than a centimeter when wide open.
Jack, yes, ensuring the focus with a manual lens is another big issue. That's why I leaned against the wall when I shot the initial two images, which helped.
If you use an AF lens, you can raise the hit rate by switching the camera to AF-C mode instead of AF-S, which was an advice from Erik Lund. In addition, the focusing unit or element in a smaller format camera is smaller and lighter, and need to travel shorter for the focusing than the one in a larger format camera, which makes the focusing response much quicker. Of course, the larger DOF due to the shorter focal length also helps.
