I can't now remember where I've mentioned this, so apologies if it's redundant, but one of the ring flashes that shows up from time to time is the old Lester Dine "auto macro light" which includes a ring light, usually defaulting to 52 mm. filter thread. The controls are somewhat limited because it was intended for use with a specific lens (the Dine 105 I think, which I think was a Yuzo lens). But if you peel off the overlay on the back, it reveals the controls for a Yuzo YU 20 flash, with several added features for general auto use that were masked off, making it a bit more flexible. These show up pretty cheaply at times, and work well. Since the various TTL options won't likely work now anyway, they're all the same for manual and auto use.