Originally Posted by jasoraso
ThomasAV, you are correct. For a 100" screen, with maximum zoom, the greatest distance for the lens of the Viewsonic Pro8200 from the screen is 15'7". The offset will be 16.8". If you play around with the various variables in the ProjectorCentral calculator, you will notice that for a given screen size, the offset is constant, regardless of the amount of zoom. I can confirm that is correct. (offset doesn't change w/ zoom).
One other item to note - for a given screen size (100") - for the Viewsonic, the available mounting range is 10'2" to 15'7". Note that the offset stays the same. Also note that for the 100" screen size, the brightness of the image will vary between 34fl at 10' and 25fl at the 15' mounting point.
For comparison, the Epson 8350 is much more flexilble in its mounting options, but that isn't necessarily a good thing. For a 100" screen with the Epson 8350, the zoom allows mounting anywhere between 9'9" and 20"9". Quite a range. However, the Fl of the image varies from 34Fl at 9'9", to 14fl at 20'9" is a very large change. In the case of the Epson, you probably would want to mount the projector based more on desired light output, rather than the easiest installation point.
Depending on your room and viewing conditions (lights, windows, wall color), your desired light output from the projector may dictate the mounting position more so than other factors.
One last consideration - I believe the ProjectorCentral Calculator is pretty accurate with regards to the math calculating throw distance, zoom range, and offset. However, the Fl calculations are taken straight from the manufacturing supplied information as well. You should factor in the fact the Fl output of a projector varies greatly over its life and depending on the calibration/mode (eco, full brightness v. theater selection).
CoderGuy, an owner of a Viewsonic Pro8200, and frequent poster, has a link in his signature to a calculator that has a little more real-life calculations for the Fl you can expect out of a projector.
jasoraso! Thank you for your helpful reply! Sorry I couldn't reply back sooner. But here goes...
Look what came on Friday!
Thanks for the confirmation of the offset and the range of where I can place the projector. Also good point about the amount of light that is actually hitting the screen and how the zoom/wide end of the lens decrease/increase the amount of light that gets to the screen.
Here's a picture of my room and the measurements that I wrote in on it, excuse the distortion, I used a fisheye lens to fit the whole room in:
The ceiling is 8', the possible mounting spot is about 14-15' from the screen (which will drop down in front of the wall mounted PRO-151FD, the screen I am looking for now is the AT Elite Motorized 100" screen (1.0 gain). As you can see I have a ceiling fan right int he middle of the room, and it comes down 17" (max, the light handle thing) So I have a couple of questions about this:
1) With mounting the projector as shown, and given the seating arear, will the PRO8200's fan be audible? I'm not worried about it on full lumen mode, watching sports during the day, more worried about ECO mode, watching movies at night during quiet scenes, the fact that it'll be mounted right above, or slightly in front of the seating area is what worries me.
2) Per my picture, will the 16-17" offset drop like the RED line in my photo or gradually down like the GREEN line in my photo?
3) The screen I am looking at is showing a "10 inch top black border" and with a 4" casing, leaves me at the picture being 14" from the ceiling. So it looks like I'll have to tilt the projector up slightly to make up for the offset, and use digital keystone. I've read that this is generally pretty bad, what is everyone's experience on keystone with the PRO8200?
The digital keystone is probably my biggest concern and I really want this projector to work. The worst case scenario, I would have to refund this projector in favor of a more expensive 3LCD projector for all the horizontal and vertical tilt shift lenses.