for the size of the lens field of view of the c mount adapter, in the design process, the size of the camera sensor imaging target should be considered. When the field of view of the lens is smaller than the target plane of the camera, "black border" and "dark corner"will be appear.
The general microscope c mount adapters are generally designed for the 1/2'' camera targets. When a camera of 2/3 or larger target is used, the dark corner phenomenon will appear in the field of view. Especially, at present, DSLR camera c mount adapter will have black border.
Generally, the dark corner that appears on the field of view is often that the center of the microscope and the camera are not aligned. Adjust the position of the screw on the camera adapter, or turn the camera adapter to adjust or change the effect.
