Photographers who are using digital cameras have a wealth of options when it comes to lenses. Many major camera manufacturers, including Canon and Nikon, have ensured that their lens mount systems are backwards compatible. This allows photographers to use an older SLR lens on a digital camera body with little effort. Converting an SLR lens to digital only requires extra steps if the lens mounts being used are no longer compatible.
Remove the lens from the film camera, if necessary, and examine the mounting mechanism. Certain digital cameras, such as Nikon and Canon, allow older lenses to be used on new camera bodies. Place a protective cover over the lens mount on the film camera to prevent dust from settling on the mechanism.
Remove the protective cover on your digital camera lens mount. This should expose the lens mounting ring and mechanism. Examine the mount to see if it matches the mount on the lens. Cameras such as Nikon and Canon brands will be likely to match with Nikon and Canon lenses; third party lenses such as Sigma or Tamron may not match.
Examine the electrical contacts on the lens, if they are present. Certain lenses for film may have contacts which do not match or prevent the lens from being used on a digital camera body. Check to see if the contracts are retractable; if they are not, they may need to be filed or removed before use. This can impair the functioning of the SLR lens and remove features such as metering and autofocus, but still leave the lens usable as a manually adjustable piece.
Check to see if a converter is available for lenses which do not match the digital camera body. These adapters are sold by photography supply shops; however, adding a converter will change the focal length and amount of distortion on the lens. Attach the converter to the lens; this process will vary based on the type of SLR lens and type of converter.
Insert the lens mount into the camera body. Do not force the lens to move or turn. Attach the SLR lens using the mounting mechanism on the camera body.