They can't tilt the lens. That would introduce keystone or other distortion into the image. The shift upwards is called the image offset. Which specific model of projector do you have? You really should not be tilting your projector up or down as you will have to use keystone correction which degrades image quality. Instead, you should put the projector exactly where it needs to go. The range of offset of projectors is vastly different from model to model, but by example, the Optoma HD20, has an image offset of 16% of image height. So, for a 50" tall image, you have to put the projector about 8" below, or 8" above (if ceiling mounting) the desired image. I like projectors with less offset as you can be closer to the edge of the screen. The BenQ W1070 has very little lens offset. Likewise, there are projectors with optical lens shift which allows the lens elements to be moved to change the offset. This offset can be shifted not only up and down, but often left to right as well. Very cool feature.