Ramsay developed an interest in photography at an early age after receiving a camera from his grandfather. He went on to study cinematography at AFDA, the School for the Creative Economy in Johannesburg, completing a four-year honours degree in 2005.
Following his studies, Ramsay began working in the South African film industry, building experience on short films and feature productions. His early credits included Lullaby (2008), Shirley Adams (2009), directed by Oliver Hermanus, and District 9 (2009), on which he worked with the documentary unit. He continued his collaboration with Hermanus on Beauty (2011), which screened in the Un Certain Regard section of the Cannes Film Festival.
Ramsay later worked on Moffie (2019), another collaboration with Hermanus. The film earned him a nomination for Best Cinematography at the British Independent Film Awards. His subsequent feature credits include Mothering Sunday (2021), directed by Eva Husson, Living (2022), See How They Run (2022) and All of Us Strangers (2023), directed by Andrew Haigh. For Living, Ramsay won the Bronze Frog award at the Camerimage cinematography festival. All of Us Strangers earned him the British Independent Film Award for Best Cinematography.