The 1.2:1 throw range of the Epson Powerlite 1735W is rather typical of lightweight, sub-five pound projectors. If you need more placement flexibility, you'll most likely need to go to a larger projector in the 6-8 pound range, and even there, many only offer 1.2:1 throw ratio. A limited zoom like this is more to let you exactly fill the screen, once you have placed the projector approximately where it needs to be.
The manual, for some reason, does not provide precise measurements from lens to screen, and even its one attempt, is only for a 4:3 aspect ratio screen.
For a 100" 16:9 diagonal screen (16:10 screens are rare), you can place the front of the projector as close as 86 inches as far back as 105 inches. For a 4:3 100 inch screen the ranges are 95" and 115".
Mac users planning on installing one of these projectors take note, the user manual does not provide precise placement information. To get this information I had to call the dedicated "Private Line" support number. Epson does provide a downloadable throw distance calculator, but so far, it's only available for Windows not Mac.