For the first time in a Q-series camera, the Q3 43 has an apochromatically corrected lens, which Leica refers to by the designation APO.
The Q3 43 also inherits the Q3's upgraded phase and contrast detection autofocus system with eye and animal recognition.
These allow for non-destructive modification of the camera's JPG output file to make the image appear more like traditional film photography, in a manner similar to the Fujifilm X series.
Compared to the Q3, it offers a narrower 43mm focal length with an APO lens and costs $600/€800 more than the Q3.
Its primary competitors are the increasingly outdated but also full-frame Sony RX1R II, the similarly styled but smaller-sensor Fujifilm X100VI, and the extremely compact Ricoh GR III that shares the 28mm field of view.