The invention relates to a composition with at least one polymerizable binder, wherein the composition contains a photoinitiator mixture which contains (a) at least one diacylgermanium compound of general formula (I) in which R1, R2 independently of each other are a linear C1-4-alkyl, or C2-4-alkenyl radical, which can be substituted by one or more polymerizable groups; R3, R4 independently of each other are in each case H, halogen, a branched or linear C1-4-alkyl or —O—C1-4-alkyl radical; R5, R6, R7 independently of each other are in each case H, halogen, a linear C1-20-alkyl, -alkenyl, -alkoxy or -alkenoxy radical, which can be interrupted by one or more —O—, —S— or —NR8— radicals and substituted by one or more polymerizable groups; and R8 independently is in each case H, a C1-20-alkyl, -alkenyl, -alkoxy or -alkenoxy radical, (b) at least one α-diketone and (c) at least one accelerator, as well as the use of the composition for example for producing a filling composite.