Epson doesn’t say anything describing the optical system of this ultra short throw projector, but I’ll say, it’s very different than traditional projectors. The bottom line is that it projects from a very short distance, and puts up on your screen a proper rectangular image with very acceptable levels of optical distortion that manages to be focused across the screen. Well, like any projector, the entire screen isn’t perfectly sharp, but it resembles similar edge to edge focus of typical projectors.
Think about it, what makes this so tricky, is that, on say, a 100” diagonal screen, the closest part of the screen assuming the LS100 is table top) to the optics will be about one foot, while the upper corners will be about 5 feet away. And think of the angles too:
The projector has to project to the left and right bottom of the screen at almost a horizontal angle (about 10% above – a quick guess) while also having to be sharp, and evenly bright at the top and the corners.
To focus the projector, you’ll find the control hiding behind the door for the air filter on the right side (if you are facing the screen). It sides up and down to focus.
Here are some basic numbers on placement of the LS100 relative to your screen. The LS100 does have some zoom lens ability, so there are two distances quoted for each screen size - closest and furthest back.
Measurements are from lens to screen. The lens itself is located 13.7 inches from the rear of the projector (that closest to the screen).
For the smallest screen size:
70 inch diagonal: The lens of the projector sits just 15.9 - 22 inches from the screen (of course it’s slightly below the screen, where the screen would be if it came down further). Apparently after a point, the zoom aspect is out of range, so that for 100" or larger there's no adjustable distance per the manual. Since the lens is 13.7 inches from the part of the projector closest to the screen, therefore, the closest part of the projector sits between 2.2 and 8.3 inches back from the screen.
For a 100" diagonal screen size: The lens sits just 23.3 inches away.
For 130” diagonal screen size (the largest): , the lens sits just 30.7 inches away.
The size of the screen also affects where the LS100 sits in terms of height:
70” diagonal: The bottom of the screen is 5.1 inches above the lens
100” diagonal: The bottom of the screen is 8.4 inches above the lens
130” diagonal: The bottom of the screen is 11.7 inches above the lens
The foot of the projector furthest from the screen sits almost directly below the lens, so that, for example, with the largest sized screen - 130" diagonal, that foot is about 30 inches from the screen, which means that a 30 inch deep credenza or table sitting just a couple inches from the wall and screen should work fine.