When I installed my projector I made sure it was level. I suppose I checked the wall at some point but not with a long enough level to span the entire height of the wall.
It looks fine and I havent noticed any keystone problems, but I went to build a frame for the screen I noticed the top half of the image didnt fill the frame! There was a .5" gap on both sides at the top and it filled the frame at the bottom. I guess the top of the wall is closer to the projector than the bottom.
On a 120" screen with the naked eye you dont really notice this amount of keystone, but as soon as I put a black velvet frame around it it became evident.
Will I encounter any problems tilting the projector (up I suppose) until the image lines up square on the wall without any keystone? I assume the small amount that it is off is just a minor adjustment on the mount. Unfortunatly the mount is 15 feet up in the air so I have to borrow my neighbors ladder to get up there!