Summary
How do I calibrate a lens if I am experiencing problems with lens cast?
Place the LCC plate flat against the front of your lens. Adjust the shutter speed 2 stops to compensate for the plate blocking some of the light. Take an image. Create the LCC on the LCC tool in Capture One.
In-Depth
Perform a Lens Cast Calibration.
Lens cast is a result of the sensor being exposed to light from a very sharp angle and will typically occur as a green cast in one corner of the image, stretching into a magenta cast in the opposite corner. Capture One's LCC tool can correct towards uniform light (to correct for lens vignetting) as well as dust.
To correct for lens cast, follow this procedure:
1. Place an LCC plate as close to the front of the lens as possible. It is imperative that no light pass through the lens without first passing through the LCC plate.
To ensure the correct exposure, it may be necessary to increase your exposure time or put more light directly on the plate in dark conditions or setups. The placement of the source of light is irrelevant as the LCC plate will diffuse the light evenly.
2. Select the thumbnail of the captured image in Capture One and open the Lens tooltab (or create an LCC floating tool via Window > Create Floating Tool > LCC
3. Select the LCC menu and click Create LCC. A dialog will appear, giving the options to include dust correction as well as Wide Angle Lens with Movements correction. The latter is designed to correct for specific banding at the extreme edge of the image circle on higher resolution digital backs.
A progress bar will appear. When the analyzation is complete, the thumbnail will have an LCC label at the top.
4. Select the LCC-labelled image as well as any image you'd like to correct. Right click on any image and select "Apply LCC" to apply those corrections to all the images. The same adjustment necessary to shift the LCC plate to neutral will be applied to these images as well.
Note that the LCC tool now shows what LCC file is applied to the selected variant, as well as offer the option to disable Color Cast, Dust Removal and Uniform Light. Under these options is a slider to control the intensity of the Uniform Light correction.
It is very important to note that Lens Cast is a direct result of the relationship between the lens plane and sensor plane. If there is any change to this relationship (technical camera movements, swings, changes in lenses, etc), the LCC will be incorrect. It is highly recommended to capture the LCC plate shots while in the field or take copious notes on movements, should you use them.
LCC correction files are stored within the CaptureOne/Settings100 (or Settings[your version]) subfolder if you are working in a session. If you are in a catalog, the LCC information is saved into the catalog itself. If you pack or export a file as an EIP, the LCC adjustment info is included in the EIP as well.
An LCC file is restricted for use only with the serial number of the individual back. Since sensors are unique and the camera calibration files that our R&D team develops for each sensor is unique, the LCC files can only be used with raw files from that same specific camera.