With my screen up and image filling the screen, I've noticed a slight upward bowing of the bottom edge of the image. The 11HT is ceiling mounted projecting onto a fixed screen. Keystone is on -3. The corners of the image meet exactly at the corners of the screen, but along the bottom the image curves upwards approx 1cm at the centre. Its a small amount but obvious from the sitting level. Does anyone else have this effect? Perhaps its just an optical trait of the lens? Miro.