Hi,
Data from mk_ and Howardlong has been added, so has my own 2465B:
It does not quite live up to it's specification or I'm doing something wrong with it using the 10x mag
It looks like your 500ps timebase is OK.
You need to adjust the vertical gain so that the square wave top is at the solid line above the top dotted line, and the square wave bottom is at the solid line below the lower dotted line. Then the two dotted lines will be at 10% and 90%. Set the two cursors where the trace crosses the 10% and 90% dotted lines.
That should give a better result.
Also, I've noticed on my analog scopes, the shape of the trace varies some between channels. Is that because the analog scopes are old and need some TLC? Or was there that much variation when they were new? I don't know.
You might want to try 1 and 2 to see if there is a noticeable difference.