Macro Shots Taken Inside Instruments (2012)
fstoppers.com
fstoppers.com
It doesn't for significantly non-zero magnification like this.
Therefore a physically small camera (think a phone camera) will have a wider depth of field, for a given scene and f-number, than a larger camera.
In other words, the inside of a guitar is a relatively large space if you're a tiny camera with a 5mm focal length.
https://www.behance.net/gallery/340016/ART-DIRECTION-INSTRUM...
The one at the top of the page (2nd in the sequence of smaller images farther down) is not a violin, cello, flute, or pipe organ.
It looks like a classical guitar, although only 5 strings are visible. The missing string would be to the left of those 5, and so may be hidden due to the angle of the shot. (We can tell it is the left that is missing because the 3 strings on the right are more opaque than the 2 we see on the left. On a classical guitar the three high strings are plain nylon, and the three low strings are a nylon core (or sometimes a synthetic fiber blend) with a metal wire wrapped around them).
The 6 strings of a classical guitar are centered over the sound hole and these look to be displaced to the left more than I would expect just from perspective but maybe I'm misjudging the perspective by subconsciously judging it as if this were a room sized space or something like that?