How do I find a point-and-shoot camera specifically for bokeh / a very shallow depth of field?

I will be getting a point-and-shoot camera for taking portraits and only portraits. Specifically portraits with a shallow depth of field. Groups portraits sometimes. It's just too much work to add lens blur at post-prod. I understand that setting a P&S on macro mode gives a shallow focus and DOF.

How do I read P&S camera specs to shortlist those with the shallowest depth of field?

Added: By point-and-shoot, I mean a camera that is easy to use -- Not necessarily compact, inexpensive, or current.

Also, if there are two or three factors/specs to get a shallow depth of field, then which spec contributes the most to bokeh? which is second most contributing? the third, etc.?

Answer

I think you'll be best served by a large-sensor compact camera, often called a "mirrorless", EVIL, or SLD. A smaller sensor impacts depth of field. A typical high-end P&S like the Canon G12 has what's called a "1/1.7" sensor. This is approximately ¹/₃rd the width of an APS-C sized sensor, which means that the depth of field wide open at f/2.8 is equivalent to about f/8 on a larger sensor. (Assuming the same framing and same-sized prints.) The Olympus XZ-1 does a little better, with a faster f/1.8 lens and a slightly larger sensor, but even then, the wide-open depth of field is equivalent to f/6 on an APS-C camera.

So, there's this relatively new category of cameras with large sensors but no reflex mirror as in an SLR — they've got a point-and-shoot-like rear LCD, and sometimes a smaller viewfinder LCD as well. Some of these aim to basically be smaller alternatives to SLRs, but many models also aim at the P&S market — focusing on simplicity and ease of use over sophisticated control.

Recent models which fall in the "simplicity" category would be the Sony NEX-C3 and Panasonic DMC GF3. There's also models from Olympus and Samsung. The Sony and Samsung models have APS-C sensors, same as entry/midlevel DSLRs. Panasonic and Olympus use somewhat-smaller "micro 4/3rds" sensors (which are still much bigger than those in a typical P&S).

These cameras also offer interchangeable lenses, so you could get a nice, fast prime to match. This shouldn't be overlooked, because the quality of bokeh is dependent on the lens design, and there's a lot more to it than aperture and sensor size.

Oh, and I should add: one feature that's pretty much vital for your use case is a proper Aperture Priority mode — usually Av or A on the dial (but not to be confused with A for Auto!). You'll probably want to use so that the camera computes exposure automatically but can be instructed to use a given wide aperture for shallow depth of field.