the metadata is sourced externally via the exiftool command.
first make sure exiftool is installed on your system and the binary
is in the system or user PATH. the flags passed to exiftool to create
the view in the metadata expander in lighttable mode is defined in the
~/.config/vkdt/config.rc file:
strgui/metadata/flags:-l -createdate -aperture -shutterspeed -iso
this default command will print in two line format (-l) the information
that follows after it. consult man exiftool for more options.