In this paper we analyse the evolutionary status of three open clusters : NGC 1817 , NGC 2141 , and Berkeley 81 .
They are all of intermediate age , two are located in the Galactic anti-centre direction while the third one is located in the Galactic centre direction .
All of them were observed with LBC @ LBT using the Bessel B , V , and I filters .
The cluster parameters have been obtained using the synthetic colour-magnitude diagram ( CMD ) method , i.e .
the direct comparison of the observational CMDs with a library of synthetic CMDs generated with different evolutionary sets ( Padova , FRANEC , and FST ) .
This analysis shows that NGC 1817 has subsolar metallicity , age between 0.8 and 1.2 Gyr , reddening E ( B - V ) in the range 0.21 and 0.34 , and distance modulus ( m - M ) _ { 0 } of about 10.9 ; NGC 2141 is older , with age in the range 1.25 and 1.9 Gyr , E ( B - V ) between 0.36 and 0.45 , ( m - M ) _ { 0 } between 11.95 and 12.21 , and subsolar metallicity ; Berkeley 81 has metallicity about solar , with age between 0.75 and 1.0 Gyr , has reddening E ( B - V ) \sim 0.90 and distance modulus ( m - M ) _ { 0 } \sim 12.4 .
Exploiting the large field of view of the instrument we derive the structure parameters for NGC 2141 and Be 81 by fitting a King profile to the estimated density profile .
Combining this information with the synthetic CMD technique we estimate a lower limit for the cluster total mass for these two systems .