I ordered a model F2 Beam Extender from Visual Echos. I received the lens last night and had a chance to
try it out few minutes ago. This is on A700 with Sigma 70-300 Apo lens at 300 and HVL58 flash. I was about 25 feet away from the lamp shade and the lamp shade was in a dark room and the door to the room is ajar. The fit on HVL-58 is not very snug but good enough. I don't know how Minolta flash is designed but the rounded edged of HVL58 prevents a snug fit against the lip of the bracket.
With best regards,
With Beam Extender and Flash in ADI mode:
With Beam Extender and Flash on Pre-flash TTL mode (recommended by Visual Echos)