I'm having an issue with vignetting on my microscope images, and I'm not really sure how to troubleshoot it, or if there is anything I can do to fix it. Below is an example image that should illustrate the issue I'm seeing fairly well - the design is completely uniform in the horizontal dimension. Viewing the image through the binocular eyepieces, the color and light intensity appears uniform.
This isn't an issue with focusing, as the image looks good in all portions of the captured image. The subject is flat, and somewhat reflective. The camera is basically an image sensor with threading for a microscope and a USB connector, and doesn't appear to have any focusing optics, or a mechanical shutter.
My goal is to take images at this magnification and stitch them together in post processing, but the vignetting results in visual artifacts that remain. I'm not sure what information would be helpful, but I can certainly answer questions