About 1:26 into the film, there is a scene where Ingrid is sitting in a chair and the poison cup of coffee is sitting in the foreground, camera right. Both are almost perfectly in focus, even though the cup appears to be much closer to the camera (and so it appears about 1.5 times the size of Bergman's head). That is because the cup was actually a prop that was about three feet tall and is placed not far from her face.
Hitchcock used a similar trick in "Spellbound," near the end of the film where the killer holds the pistol in his hand and it follows Bergman's character (Constance) as she leaves the room. They created a giant prop so that both the extreme close-up of the gun and the background action of Constance walking are in focus.
It is better to be kind than to be clever or good looking. -- Derek
There are several ways of achieving the effect described, one being the giant prop method employed in Notorious and Spellbound (as mentioned by pt100).
Another - and the easiest - is by increasing the depth of field through lighting and aperture control. The smaller the aperture opening, the greater the depth of field (objects from foreground to background in focus) and the more light required. Cinematographer Gregg Toland was a master of such photography, and his work on Citizen Kane, The Little Foxes and The Best Years Of Our Lives, for instance, features many fine examples. In both Notorious and Spellbound, this method was rejected because the moody lighting desired for Ingrid Bergman in these shots couldn't be accomplished with the entire set flooded with light.
Hitchcock was after a similar effect in Stage Fright in a shot with a closeup of Marlene Dietrich in the foreground and Jane Wyman across the room in the background, with both in focus. Dietrich was notoriously fussy and controlling over how she was lit and shot, so the Toland method was out. And for obvious reasons, a giant replica of Marlene was out as well. So a master shot of Wyman in the distance was made without Dietrich, and then a separate closeup of Marlene (lit as she demanded) was made, which was then optically printed into the master shot with a traveling matte.
In Lifeboat, when Canada Lee recites the 23rd Psalm in closeup at screen right with other players in the distance screen left, looking over the side where Mrs. Higgins' baby has just been buried at sea, the stopped-down aperture method was used with low lighting everywhere except on Lee and the sky backdrop, leaving Tallulah Bankhead and the other players in focus but darkly silhouetted against the sky.
Unless I don't understand what you are trying to say, Doghouse-6, this (not very large DOF) is what Toland is known for.
Often, they had custom made lenses built for this. Not just split, but one side could be cut out to be the rough shape of the one item they wanted to focus on. Saw one long ago. Crazy expensive, I assume, but cheaper than a giant teacup?
Unless I don't understand what you are trying to say, Doghouse-6, this (not very large DOF) is what Toland is known for.
I think we're on the same page as far as the onscreen effect - foreground as well as background persons/objects in focus - but if you'll forgive a small correction, this type of shot (for which Toland was known) is the opposite of what you describe: greater, rather than lesser, depth-of-field.
The links you provide discuss means of achieving them not in use at the time of the examples I mentioned: external lens adapters in the form of either a split-focus diopter (which became popular after the advent of widescreen formats in the '50s) or glass plate (the latter being something I've never heard of and know nothing about).
What I was referring to utilized a fixed focus lens with no external adaptation, and achieved the effect by the means described at the beginning of the second paragraph in my 5/14/15 post.