Context : Unlike young open clusters ( with ages < 250 Myr ) , the Hyades cluster ( age \sim 600 Myr ) has a clear deficit of very low-mass stars ( VLM ) and brown dwarfs ( BD ) .
Since this open cluster has a low stellar density and covers several tens of square degrees on the sky , extended surveys are required to improve the statistics of the VLM/BD objects in the cluster .

Aims : We search for new VLM stars and BD candidates in the Hyades cluster to improve the present-day cluster mass function down to substellar masses .

Methods : An imaging survey of the Hyades with a completeness limit of 21 \aas@@fstack { m } 5 in the R band and 20 \aas@@fstack { m } 5 in the I band was carried out with the 2k \times 2k CCD Schmidt camera at the 2m Alfred Jensch Telescope in Tautenburg .
We performed a photometric selection of the cluster member candidates by combining results of our survey with 2MASS JHK _ { s } photometry .

Results : We present a photometric and proper motion survey covering 23.4 deg ^ { 2 } in the Hyades cluster core region .
Using optical/IR colour-magnitude diagrams , we identify 66 photometric cluster member candidates in the magnitude range 14 \aas@@fstack { m } 7 < I < 20 \aas@@fstack { m } 5 .
The proper motion measurements are based on several all-sky surveys with an epoch difference of 60-70 years for the bright objects .
The proper motions allowed us to discriminate the cluster members from field objects and resulted in 14 proper motion members of the Hyades .
We rediscover Hy 6 as a proper motion member and classify it as a substellar object candidate ( BD ) based on the comparison of the observed colour-magnitude diagram with theoretical model isochrones .

Conclusions : With our results , the mass function of the Hyades continues to be shallow below \sim 0.15 M _ { \odot } indicating that the Hyades have probably lost their lowest mass members by means of dynamical evolution .
We conclude that the Hyades core represents the ‘ VLM/BD desert ’ and that most of the substeller objects may have already left the volume of the cluster .