Hi Lew, **In another set they used 200X to get a very close up view of the working surface of the stylus tip. This tells me that anything more is superfluous. Does anyone disagree?**
I used to examine styli professionally with an Audio Technica microscope designed for that purpose. Magnification was 100, 300, and 500X. 200X might be adequate for most styli, but some of the micro - extended contact types, like microridge are very small. I'd think you would need at least 400X. USB scopes are not really designed for stylus wear examination. You need 2 high intensity lights to illuminate the sides of the stylus. Wear is determined by the light reflecting off the sides. When a stylus is new, you only see a dot of light. As it wears that dot spreads into a larger area. That larger area is flat, and reflects the light.
A picture chart came with the scope that showed the different types and examples of wear. 100X is useful for checking for cracks, chips and general condition. I know the old Shure scopes were 200X. I believe these were made before micro type styli were invented. You can see how small the picture is in the link. A micro type is much smaller and it becomes impossible to evaluate wear.
Regards,
