\setuptolerance[verytolerant, stretch]
\setupalign[hz, hanging]
\definefloat[subfigure][subfigures]

\setupfloat[figure][]
\setupfloat[tableleft][]

\setupcaption[figure][width=max, align={hz, hanging}, style=sstf]

\setupcaption[subfigure][way=bypage, location=top, width=max, align={hz, hanging}, inbetween={\blank[1*small]}, style={\smallbodyfont\sstf}, numberconversionset=characters, numberstopper={)}, prefixsegments=4:100]





\starttext

\input tufte

\placefigure[left, force, -13*line]{Maincaption}
{\startcombination[2*2]
{\offset[y=12.24\baselineskip]{\clip[height=22.24\baselineskip, width=5cm, hoffset=5cm]{\externalfigure[Abax_parallelepipedus] [height=18cm]}}}
{\offset[y=12.24\baselineskip]{caption 1}}
{\clip[width=5cm, height=10\baselineskip]{\externalfigure[Amara_aenea][height=11\baselineskip]}}{caption 2}
{}{}
{\clip[width=5cm, height=10\baselineskip]{\externalfigure[Andrena_flavipes][height=\figureheight]}}{caption 3}
\stopcombination}

\input tufte

\stoptext