I have a ring flash from sometimes between '70s and '90s, it is a Euro Blitz V60 PK (PC sync, no hot shoe).
The diameter of the thread is 52 mm and I could use it with my Nikon 35 mm F1.8 DX, but not with my Sigma 17-50 mm F2.8 DX (77 mm filter diameter).
Is there a way to adapt it? I can also consider DIY if I find good projects (like off-axis with simple light guides).
I am aware of the different trigger voltages and I will be careful not to fry my dSLR.
Well the internal circuit blew up due to leaks from capacitors and the usual white spongy deposit everywhere. Still, the question stays valid.
About the question: apart from a stepping down adapter, is there a way to expand the radius of the ring, by using something like http://photo-tips-online.com/review/ray-flash-ring-flash-adapter/gallery.php?id=ray-flash-ring-flash-adapter-full but from small ring to bigger ring, instead of from popup flash to ring flash (as in the link)?