Konica Minolta system flashes actually have a slightly shifted zoom range from the focal lengths of the lens. The reason is that this way a loss of brightness in the image's corners is avoided. Such a loss of brightness might occur due to the differences of properties between the optical system (lens and ccd/film) of digital and analogue cameras.
The wider angle of flash illumination leads to a decrease of the guide number because the same amount of light energy is spreaded over a wider space. This is necessary though to avoid darker corners. If you prefer to use a higher guide number you have the choice to use the manual zoom of your Konica Minolta system flash unit.