Indian custom duty on Sony camera worth 3000 Dirhams or Rs.36750/-?

I plan to come to India from Dubai this year with a Sony DSLR camera which costs about Dhs.3000/- or Rs.36,750/-. I have heard that the used camera is free of duty. But how can I prove that if it is used or not? And if I bring a lens worth Rs.30,000/-, is it dutiable separately? What is the tax amount payable on the excess amount over 25,000/-? Please see that I am coming to India after ten months of stay in Dubai and am holding the status of an NRI.