Last week, though, Sony introduced another jaw-dropping step forward in the big sensor/small camera race: a tiny machine called the Alpha NEX-5 . It won’t be available until July, but it may be worth waiting for.

Like the Samsung, the NEX-5 contains an APS-C-size sensor — awesome. Yet this camera is amazingly, crazily small. It’s half the weight and volume of a small S.L.R.; in fact, without the lens, it’s about the size of a regular pocket camera (4.4 by 2.4 by 1.6 inches — only an inch thick except at the grip bulge). The lens barrel is actually taller than the camera itself.

Anyway, it’s the smallest interchangeable-lens camera in the world. With lens attached, the tiny NEX-5 looks a little bizarre — even ridiculous, like a mere backplate for a lens. But keep an open mind; it still handles well.

Image The three-inch screen flips up or down, for shooting above or below eye level.

Now, to get this small, Sony had to push the envelope — and pull it, fold it and spindle it. As with most other hybrids, this one has no built-in flash and no eyepiece viewfinder. (A tiny snap-on flash comes with the camera, and a glass viewfinder that works with the standard lens will cost about $200 and will become available in July.)

And there’s room for only six buttons, compared with about 25 on an S.L.R. Yet the camera offers most of the controls of a typical consumer S.L.R., plus some great features from amateur cams.

The price is right: $600. Or you can save $100 and get the NEX-3, which has a plastic body instead of a metal one. For that price you get a non-zooming 16-millimeter lens (24-millimeter film equivalent) . On the camera, this lens is flat enough to fit in a coat pocket, but beware some distortion at the edges of the frame. For $50 more, you can get either camera with a 18-55-millimeter (3X zoom) lens instead. An 18-200-millimeter (11X zoom) lens will be available this fall for about $800.