I agree with Primary Arms. I set my diopter on 1x from a distance of 10 ft and adjust the diopter til the image is as flat and as close to 1x as possible. I do have a question you may be able to help with. If you're in a dark room or looking as a dark backdrop, do you have specs on your lens (internally) that you only see when the illumination is on? Typically, on setting 7 or higher.
