i use a dino-lite 211 for measuring sra. it does the job nicely. what you do need is a very stable support for the scope, like a decent tripod and a macro focusing rail. i posted a discussion on another forum about this. i was coached by wally malewicz and michael fremer on how to measure sra using the scope. they were vary helpful.
http://www.canuckaudiomart.com/forum/viewtopic.php?f=32&t=16986&hilit=stylus+rake+angle
http://www.canuckaudiomart.com/forum/viewtopic.php?f=32&t=16986&hilit=stylus+rake+angle