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Modern direct injection spark ignition (DISI) engine concepts have the drawback of higher particulate matter emission as compared to port fuel injection concepts. Especially, when driven with biofuels, the operation of DISI engines requires a deeper insight into particulate formation processes. In this study a modern optical accessible DISI engine is used. Pure isooctane, ethanol, E20 (20vol% of ethanol in isooctane) and E85 were investigated as fuels. Simultaneous OH*-chemiluminescence and soot radiation imaging was conducted by a high-speed camera system in order to separate premixed combustion with the sooting combustion. Furthermore, a laser-induced incandescence (LII) sensor was used to measure exhaust elementary carbon mass concentration. Systematically, operation points were chosen, which correspondent to the main sooting mechanisms, poolfire, mixture inhomogeneities and global low air-fuel ratio. Furthermore, they were compared to a homogenous charge combustion strategy.