I'm using an old Minolta Auto 25 flash off camera wireless to my FUJI XT2. There is no manual power setting switch, only an ISO setting dial. I do not want to use auto mode, but I also do not want to increase flash to subject distance to lower light intensity. So, if I set the flash ISO setting dial to 800, will the flash emit less light/power than if it was set to the same ISO setting as the camera, in this case, say 100?
In other words, if the camera ISO is set at 800, it makes the sensor more sensitive to light. So if I set ISO on the flash to 800 and the camera to 100, is it fooling the flash to emit less light believing it is providing enough light to the camera if the camera setting was 800?