No other band has been examined under a microscope as meticulously as the Beatles. Detailed books have even been written focusing solely on the instruments they played and the gear used to make their recordings in the studio.
But with all this exhaustive research, some details are still unknown. For example, historians may know what instruments were brought to and available for each recording session, but the exact guitars and amps used on many songs still remain purely the subject of speculation.
Although many photos were taken of the Beatles working in the studio, only one video exists of them at work while recording.
On February 11, 1968, the Beatles showed up at Abbey Road Studio Three to shoot footage for a promotional film for Lady Madonna. To make the best use of their time, they decided to record Hey Bulldog while the cameras rolled. As a result, the footage provides a definitive record of the instruments used.
Source: Chris Gill/guitarworld.com