My biggest challenge was moving from photography to film without losing my way of working - which is very intimate and learning to collaborate with more people, since photography for me is a very solitary process.

I have had the opportunity to meet men and women working in the sex trade in my travels to Mexico's northern and southern borders.

Of all the subjects I have photographed, the most controversial and the one that has moved me the most has to be the prostitutes who are getting on in years. They are true survivors.

I am in any way glorifying or simplifying prostitution. The reality of prostitutes around the world is so complex. I've tried to focus on the humanity.

My biggest challenge was moving from photography to film without losing my way of working - which is very intimate and learning to collaborate with more people, since photography for me is a very solitary process.

I have been exploring [Mexico City's] La Merced, [a public market famous for prostitution,] on and off for the last 23 years. The prostitutes and their world have been the main subjects of my photographs.

My intention has been to encourage viewers to face their prejudices about prostitution, sex and aging while reflecting on the complex and varied forms that love and loneliness can take.