MAD is the first multi-conjugated adaptive optics system at the VLT .
We present H and K _ { S } observations of the young massive cluster Trumpler 14 revealing the power of MCAO systems by providing a homogeneous Strehl ratio over a large field of view .
Mean Strehl ratios of 6.0 and 5.9 per cent with maximum Strehl ratios of 9.8 and 12.6 per cent in H and K _ { S } , respectively , show significant improvement of the spatial PSF stability compared to single-conjugated adaptive optics systems .
Photometry of our observations cover a dynamic range of \sim 10 mag including 2–3 times more sources than comparable seeing-limited observations .
The colour-magnitude diagram reveals that the massive cluster originated in a recent starburst-like event 1 \pm 0.5 Myr ago .
We tentatively detect hints for an older population of 3 Myr suggesting that low intensity star formation might have been going on in the H ii region for a few Myr .
We derive the luminosity function and mass function between 0.1 M _ { \sun } and 3.2 M _ { \sun } and identify a change of the power law slope of the mass function at m _ { c } \sim 0.53 ^ { +0.12 } _ { -0.10 } M _ { \sun } .
The MF appears shallow with power law slopes of { \Gamma _ { 1 } = -0.50 \pm 0.11 } above m _ { c } and { \Gamma _ { 2 } = 0.63 \pm 0.32 } below m _ { c } .