Hi all:
I just came across a Vivitar Auto Thryristor 2800 flah.
I have a question or maybe is two on one: In the front of the flash there is a kind of sliding tab labeled red dot, M and blue dot and a small round window under this sliding tab, what is this used for?
Is going to used with my Canon EOS 850 film camera, that is about 15 years old but still in mint condition.
Thanks
Julian