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Hmm-- crop factor for a 2/3 inch sensor is 3.6, so a 35mm lens on a 2/3 would roughly be equivalent to 125 mm-- short telephoto, good for headshots from say 6-7 feet away.
Using Depth of Field Master
an f/2/ 125mm lens, at 6 ft, has a depth of field of 0.08 ft. (Canon5D Mark III)
an f/2 35 mm, lens, at 6 ft has a depth of field of 0.28 ft (Fujifilm X10, though it's actually limited to 28mm @ f/2.8)

So if you want razor thin depth of field, best go with full frame or larger, assuming that the lenses are available-- 200 mm f2 lens can be had, but they are rather expensive.

I have an APS-C dlsr. If I put my 50mm f/1.4 lens, wide open, and photograph a subject 3 meters away, the depth of field is approximately 20 cm.
If I managed to find a 75 mm f/1.4 lens (fast 85mm lenses are far more common), and a full frame camera to mount it on, the field of view would be similar, but the depth of field would be approximately 13 cm.
Depth of field calculator
IIRC, the lumia has a 1/1.7 sensor-- bigger than most point and shoots, but smaller than APS-C, or micro four thirds-- with a crop factor of 4.2.

To get that 75 mm equivalent, the Lumia would have to use a 18 mm lens, with a 39 cm depth of field.

> most technically knowledgeable film editors and sound designers
Clearly optics isn't one of his strengths.

Anything beyond around 20 feet in a dark theater is infinity focus for the human eye and more like 6 feet in daylight.

What this means is your eye focuses the same for any objects 20 feet away or further, Such as when sitting in a theater.

So as long as the 3D isn't projecting images out of the screen at you, your eyes aren't going to notice anything unusual in focusing.

So it's all up to how the 3D content was shot.

Technical details:

What we want to know is the hyper focal distance of the eye,.
http://en.wikipedia.org/wiki/Hyperfocal_distance The closest point of focus at a given aperture, at which infinity falls within the Depth of Field

Optics of the human eye By David A. Atchison, George Smith PG 214 has a nice graph on this.
http://books.google.com/books?id=MHgx-jBA0TAC&lpg=PP11&ots=DGJxkLC644&dq=depth%20of%20field%20human%20eye&lr&pg=PA214#v=onepage&q=depth%20of%20field&f=false

Astronomers the maximum iris opening is 7mm this gives a max aperture is f/3.5.
Wikipedia says f/2.1 to f/8.3 http://en.wikipedia.org/wiki/Apertures

The focal length of the eye is 17 mm http://hypertextbook.com/facts/2002/JuliaKhutoretskaya.shtml

http://en.wikipedia.org/wiki/Hyperfocal_distance
http://www.flickr.com/photos/robertseber/2372620675/ Optimal Aperture For Foreground Sharpness With Infinity Focus
http://www.dofmaster.com/charts.html
http://www.bobatkins.com/photography/technical/dofcalc.html

I have some article on my blog about 3D content issues.
http://videotechnology.blogspot.com/2010/08/thx-and-blufocus-join-forces-to-certify.html
http://videotechnology.blogspot.com/2010/08/why-bad-3d-not-3d-glasses-gives-you.html

Depth of field doesn't just relate to the aperture size (less DoF for wider aperature/small F-number), but also focal length of the lens (less DoF in telephoto lense or the larger SLR versus compact cameras) and the distance to focussed object (less DoF if it is closer to the camera). Your statement, as the other person points out is wrong. If it requires 1/100th of the light, you might have to close the aperture somewhat, increasing the DoF. This is a really cool DoF Calculator.

If you learn about about depth-of-field, you'll find out that it is not linear, but is relative.

If you are a very short distance away from a subject, the absolute depth-of-field is smaller than if you are far away, but the ratio of out of focus near/in focus/out of focus far remains very similar.

The key is, in the out of focus part, anything without sharply defined lines should quickly blend into a blur, especially for anything with any repeating pattern (including something fractal like a rock surface). This is especially true for the out of focus far portion of the picture, as that's what gives a picture "good bokeh".

Thus, the rock in the crab shot should be fairly close to nothing but a blur, but it isn't.

Part of the reason is that most P&S cameras (including the one taking the crab shot) can't open the aperture, focus at a short distance and get a longer focal length. This is what you need for extremely short DOF. For more information, use this DOF calculator.

In the other direction, most P&S can't close down the aperture enough to get really deep DOF, although the smaller sensors do help this a bit.

I was being sloppy, of course. But you don't necessarily need a macro mode to photograph things not at infinity -- just a small aperture and use the hyperfocal distance

The parent poster is wrong on several counts.

Depth of field is dependent on the aperture, yes, but on the other hand you can actually get very fast lenses on point and shoots. Take the Sony F828 for example, which has the equivalent of a 28-200mm f/2-f/2.8 zoom. You can't buy an equivalent lens for SLR cameras. What is important to note is that this is equivalent focal length, and the real focal length of the Sony zoom is 7.1-50 mm. So in the lens area we have two competing influences: short focal length lenses lead to greater depth of field, but fast lenses lead to less depth of field. As I shall show the shortness of the lens wins out.

Yet another why the parent post is wrong is that depth of field is also dependent on the circle of confusion, which in turn is related to the photosite size on the sensor. Point and shoot cameras generally have sensors that are MUCH smaller than those on dSLRs (compare a 1.6x crop dSLR to the Sony F828 again, with its ~4x crop), so the circle of confusion is smaller and the depth of field greater.

In other words, if you're shooting at 80mm equivalent at f/2 on a Sony F828 and a Canon 20D, the Sony will have vastly greater depth of field for two reasons. The first will be that the actual focal length of the Sony lens at 80mm equivalent would be ~20mm due to the small sensor size of the Sony, while the 1.6x crop Canon would be using a 50mm lens. The second will be that the Sony sensor's smaller photosites will result in a smaller circle of confusion, and thus greater depth of field.

The originally posted article is right, at least in part: it is impossible to get a truly narrow depth of field with a point and shoot camera, and the ability to do so is a big selling point of SLR and dSLR cameras.

Reference: Using this DOF calculator, plugging in 20mm actual lens, 5 ft. subject distance, f/2.0 for the Sony, and the same but with a 50mm lens for the Canon I get the following results:

Canon: 4.89 ft is the near limit of acceptable sharpness, 5.11 ft the far limit. That's 0.22 ft depth of field, in other words. Circle of confusion is 0.019 mm.

Sony: 4.72 ft near limit, 5.32 ft far limit. 0.6 ft depth of field, 0.008 mm circle of confusion.

The moral of the story: 0.6 ft vs. 0.22 ft depth of field at the equivalent focal length and aperture. With this in mind, the reader should decide if the parent poster is full of it when he writes "One of the reasons extolled at length for choosing one type against abother is that a DSLR has a narrow depth of field and a "standard" digital camera has a greater depth. As anyone who knows about photography would know this is total tosh."

The parent poster is wrong on several counts.

Depth of field is dependent on the aperture, yes, but on the other hand you can actually get very fast lenses on point and shoots. Take the Sony F828 for example, which has the equivalent of a 28-200mm f/2-f/2.8 zoom. You can't buy an equivalent lens for SLR cameras. What is important to note is that this is equivalent focal length, and the real focal length of the Sony zoom is 7.1-50 mm. So in the lens area we have two competing influences: short focal length lenses lead to greater depth of field, but fast lenses lead to less depth of field. As I shall show the shortness of the lens wins out.

Yet another why the parent post is wrong is that depth of field is also dependent on the circle of confusion, which in turn is related to the photosite size on the sensor. Point and shoot cameras generally have sensors that are MUCH smaller than those on dSLRs (compare a 1.6x crop dSLR to the Sony F828 again, with its ~4x crop), so the circle of confusion is smaller and the depth of field greater.

In other words, if you're shooting at 80mm equivalent at f/2 on a Sony F828 and a Canon 20D, the Sony will have vastly greater depth of field for two reasons. The first will be that the actual focal length of the Sony lens at 80mm equivalent would be ~20mm due to the small sensor size of the Sony, while the 1.6x crop Canon would be using a 50mm lens. The second will be that the Sony sensor's smaller photosites will result in a smaller circle of confusion, and thus greater depth of field.

The originally posted article is right, at least in part: it is impossible to get a truly narrow depth of field with a point and shoot camera, and the ability to do so is a big selling point of SLR and dSLR cameras.

Reference: Using this DOF calculator, plugging in 20mm actual lens, 5 ft. subject distance, f/2.0 for the Sony, and the same but with a 50mm lens for the Canon I get the following results:

Canon: 4.89 ft is the near limit of acceptable sharpness, 5.11 ft the far limit. That's 0.22 ft depth of field, in other words. Circle of confusion is 0.019 mm.

Sony: 4.72 ft near limit, 5.32 ft far limit. 0.6 ft depth of field, 0.008 mm circle of confusion.

The moral of the story: 0.6 ft vs. 0.22 ft depth of field at the equivalent focal length and aperture. With this in mind, the reader should decide if the parent poster is full of it when he writes "One of the reasons extolled at length for choosing one type against abother is that a DSLR has a narrow depth of field and a "standard" digital camera has a greater depth. As anyone who knows about photography would know this is total tosh."

This is true but depth of field depends also on the focal length and magnification (which is related to the sensor size). The large magnification means that the lens "circle of confusion" should be smaller.

Try any "depth of field calculator", e.g. here and you will see that on Canon A75 at 16.2 mm telephoto (which has the same filed of view as 105mm 35mm lens) the total depth of field for an object 3m apart at f/5.6 is 2.15m

In contrast for Canon 1Ds with 105mm lens and f/5.6 depth of field is only 0.27m

Of course on 1Ds you can stop the lens to f/22 and and have the same photo with large depth of field (and because of the small noice of the sensor, you can increase the ISO speed without much degradation of the quality and have reasonable shutter speed). With DSLR you have a choice of large and shallow depth of field. With most point-and-shots you have only large.