icarus57 wrote in post #11682738
How bout when you are using a trigger system, like a pocket wizard and must use it on manual mode? so if its on 24mm, does that mean the effective range of the flash is shorter or farther?
In order for the distance scale to work, the flash must be mounted on the camera or connected via an off-shoe cord. However, even if the distance scale is not shown, the principle still applied. The effective distance is determined by applying what's referred to as the guide number (GN) of the flash at a specific head zoom position at ISO 100 (the GN is listed at the back of your flash manual).
But the general rule is that the smaller the focal length the head is zoomed to, the smaller your effective distance will be for a given aperture and ISO. This is because at a smaller focal length, the flash light is spread out more so there's less of it to light up the subject. Conversely, if you increase focal length so that the flash light is concentrated into a narrower beam, there's more light falling on the subject so that increases the effective distance of the flash for the same camera setting.