Currently, I have my G11 ceiling mounted at the back of my Theatre, lens about 12.5 feet from the screen. This turns out to be (just barely) enough to fill my 100" diagonal 4:3 screen (80" x 60"). In fact, when I was first building my Theatre, I thought I might need to mount it from behind the wall just to fill my screen. The room behind the Theatre was going to be finished also, and my wife wasn't wild about having the back-end of the projector sticking out. After a rather nervous circus act with portable DVD player, a board, a ladder, and a $9000 device balancing upside down, we happily confirmed that our original idea would suffice.
It has been that way for about 9 months, now. Although I have yet to hear any guests complain about the noise and the heat (from the projector), I have noticed that I often have to bump up the volume a couple of notches during especially quiet scenes.
As it turns out, my wife would much rather have the projector protrude from the backside than have any kind of hushbox. I tend to agree, since the projector is currently mounted under a soffit and directly above the rear row of seating. So I'm thinking, maybe I should give the idea of mounting the projector through the wall another chance.
After a little poking around in the false ceiling of the room behind Theatre, I was suddenly reminded of why I abandoned this idea so quickly before. It seems the perfect placement of the projector to be centered with the screen would be directly behind a 6x6 post which was now neatly finished inside the rear wall of the Theatre.
So, (finally) to the subject of my Thread. How much keystone will the image actually have if I move the projector off-center by, say 8 inches
Assuming my new projector throw is going to be 15' from the screen, it looks like I should see a keystone of about 1/2" from left to right. Here's the math I used.
With the projector dead center, the distance from lens to screen is 180", while the left and right edges of the screen have a distance of 184.4", no keystone
Now, we move the projector off center to the right by 8 inches. The distance to the screen is still 180", but the point of perpendicular to the screen is shifted to the right by 8" also. That would put the left edge of the screen at 186" from the lens, while the right would only be 183" from the lens. Based on what I can tell from the throw calculation, that means the image on the right will be about 1/2" smaller than the image on the left. Alas, keystone
How noticeable is this really going to be? Is everyone really THAT accurate in their installation?
It has been that way for about 9 months, now. Although I have yet to hear any guests complain about the noise and the heat (from the projector), I have noticed that I often have to bump up the volume a couple of notches during especially quiet scenes.
As it turns out, my wife would much rather have the projector protrude from the backside than have any kind of hushbox. I tend to agree, since the projector is currently mounted under a soffit and directly above the rear row of seating. So I'm thinking, maybe I should give the idea of mounting the projector through the wall another chance.
After a little poking around in the false ceiling of the room behind Theatre, I was suddenly reminded of why I abandoned this idea so quickly before. It seems the perfect placement of the projector to be centered with the screen would be directly behind a 6x6 post which was now neatly finished inside the rear wall of the Theatre.
So, (finally) to the subject of my Thread. How much keystone will the image actually have if I move the projector off-center by, say 8 inches
With the projector dead center, the distance from lens to screen is 180", while the left and right edges of the screen have a distance of 184.4", no keystone
Now, we move the projector off center to the right by 8 inches. The distance to the screen is still 180", but the point of perpendicular to the screen is shifted to the right by 8" also. That would put the left edge of the screen at 186" from the lens, while the right would only be 183" from the lens. Based on what I can tell from the throw calculation, that means the image on the right will be about 1/2" smaller than the image on the left. Alas, keystone
How noticeable is this really going to be? Is everyone really THAT accurate in their installation?