Equipment Prep
Adding A Lens
Manual Lens Calibration
Manual lens calibration allows the user to work with their own lenses by conducting a lens calibration process.
Before starting a lens calibration there are some preparation steps that can help speed up the process
Try and setup the camera in a setting that has:
- Enough “features” for natural tracking - The system uses the natural tracking core when calibrating so it is important to have suitable elements for tracking in the environment. Avoid calibrating with the camera facing a large green screen for instance
- Space – It is possible to calibrate lenses in relatively small spaces, but typically better results are achieved when the environment is larger and around 10m from the camera to the “calibration graphic” can be achieved.
- Lighting – Having stable and consistent lighting is recommended, additionally having a portable light to shine on the calibration chart can help, particularly when working at areas of the lens that are out of focus
Rigging the camera and CamBar in the following way will assist with the procedure
- Centre and facing forward – Try and place the CamBar as central as possible to the Main camera sensor. Point the CamBar forward with as little rotation as possible
- Tripod – Having the main camera mounted on a tripod (or other platform that allows for panning and tilting only) will help
- Backfocus – When calibrating a broadcast lens, ensure the backfocus has been correctly set before proceeding
- Sensor Size – If calibrating a lens that may be used on different sized sensors, it is recommended to calibrate it on the largest sensor mode first. This way the resulting lens file can be used on smaller sized sensors without needing to be recalibrated.
- Nodal – An important step of the lens calibration is calculating the “nodal” point of the lens. Having the camera rigged on a long slide plate that allows for forward/backward adjustment on the tripod will help with this
The lens calibration process can be broken down into several steps, each of which are described in the following sections