I have a flashgun that can tilt but cannot swivel. Using bounce flash off a white ceiling while taking portrait photos horizontally is ok, but when holding the camera vertically then the flash will only bounce off the wall and not the ceiling. My question is: if this wall is a light colour, will the bounce flash on the model still be suitable? Obviously if the wall is not white then there's gonna be problems with the colour of the wall being projected on the model. What are the best possibilities, other than buying a new flash, of deflecting the light upwards towards the ceiling?