If you are using the max zoom, you should try to use the max shutter that your camera can synchronise. Also, if you are too far away for your flash to reach, you can always make your own flash extender to concentrate the light spread to match your lens angle of view. This will greatly increase your flash reach. My SB26 can zoom only up to 80mm. With the extender, I can get up to 400mm which more than doubles the flash distance.