1. INTRODUCTION  
2. THE DATA  
3. DERIVING THE IMF  
3.1. Simulating the ONC CMD  
3.2. Fitting technique  
4. RESULTS  
4.1. Overall assessment of the results quality  
4.2. Broadening the simulated CMDs: the star formation history  
4.3. Broadening the simulated CMDs: the binary fraction  
4.4. Broadening the simulated CMDs: nuisance parameters  
4.5. A sanity check  
5. DISCUSSION  
6. SUMMARY AND CONCLUSIONS