National Symphony Orchestra principal bassist Robert Oppelt put together a great page of information about the wide variety of grips used by professionals on the German bow. As a French bow player, I always find myself struggling when offering advice to students on how exactly to approach the subtleties of German bow technique, and this page is a wonderful survey of the methods used by professionals.
Robert has a great synopsis of the various German bow grips commonly used, along with a photo for each one. Here’s a brief synopsis–you’ll definitely want to check out his site for descriptions of the following grips (plus the accompanying photos):
This is a fantastic resource for bassists everywhere, and I know that I’ll be referring to it frequently in my own teaching.