I like mine tilted a little to the front that way when i turn the motor if i come off the brush say when it is turn right i know i am at the right edge and if i come off the brush and say i turn it left i know the brush is to the left,it does not affect the pic, been doing it since 2d came out.if you want it straight down put a tennis ball on a weight and a float at the top of water and get near the float and see how well you see the ball and then turn motor and see if you can see the ball in all direction ,better to do it beside a dock or something and hold it still