Photographers who switch between brands no longer need to worry about selling their existing third-party lenses. Sigma is offering a service that will change a lens mount for a fee.
Swapping from Canon to Nikon, or Nikon to Canon? If you have any existing Sigma glass, the lens manufacturer will convert them to the appropriate mount for use on your new camera.
The service starts from 2 September, and lenses need to be shipped to a local Sigma office, which will then forward them to the factory in Japan for conversion. At the moment, Sigma is offering this service for its Art, Sport and Contemporary lenses — a list of applicable glass can be found on the website.
Prices start at US$80 for DN lenses, and range to US$250 for a super telephoto lens such as the 120-300mm f/2.8. Conversions are available for Sony, Sigma, Canon, Nikon and Pentax mounts. Even mirrorless mount conversions can be done, providing the lens was originally released with the mount you are requesting. Turnaround time is two to four weeks.
While the cost is not trivial, it's far less than investing in another lens should you change your camera allegiance.