We have conducted VI CCD photometry of the two open clusters NGC 1245 and NGC 2506 using the CFH12K CCD camera .
Our photometry covers a sky area of 84 ^ { \prime } \times 82 ^ { \prime } and 42 ^ { \prime } \times 81 ^ { \prime } for the two clusters , respectively , and reaches down to V \approx 23 .
We derived the physical parameters using detailed theoretical isochrone fittings using \chi ^ { 2 } minimization .
The derived cluster parameters are E ( B - V ) = 0.24 \pm 0.05 and 0.03 \pm 0.04 , ( V - M _ { V } ) _ { 0 } = 12.25 \pm 0.12 and 12.47 \pm 0.08 , age ( Gyr ) = 1.08 \pm 0.09 and 2.31 \pm 0.16 , and [ Fe/H ] = -0.08 \pm 0.06 and -0.24 \pm 0.06 , respectively for NGC 1245 and NGC 2506 , We present the luminosity functions ( LFs ) of the two clusters , which reach down to M _ { V } \approx 10 , and derive mass functions ( MFs ) with slopes of \Gamma = -1.29 for NGC 1245 and \Gamma = -1.26 for NGC 2506 .
The slopes are slightly shallower than that of the solar neighbourhood , implying the existence of dynamical evolution that drives the evaporation of the low-mass stars in the clusters .