I used a Cobra Auto2 10 (older film camera flash) on my Canon DSLR 5D mark 3 for an experiment. The flash was working fine. Then I put my newer Metz 58 AF-1 and AF-2 flash back on on the camera.
My flash images using the Metz are now underexposed. It's acting like there's no communication between the camera and flash. What could be wrong?