When I use high zoom, like 400x, I see a bit of reflection in the center of the field of view when aiming at something dark. Is that reasonably normal? It’s not excessive, and it only happens when looking at something black or very dark at high zoom.
I have two identical Olympus DPlan objectives with the same magnification, but one of them has a smaller lens or a black circle around it. What is the difference? Both work well, and the view through them is the same.