how far does the projector(front) have to be to fill 120" wall

If you are a paid member, use the lumenlab focal calculator...

http://www.lumenlab.com/forums/index.php?showtopic=29

I've recently come by a LCD panel that I would like to incorporate into a DIY PJ project, and an contemplating using brainchild's plans/desgin. However I have a question regarding the seating distance & projector distance.

I noticed that on one of brainchild's messages that he said the projector was located behind the seating area. However, if you use the lumenlab calculator for projector position using a 15" LCD and 320mm (12.6") lens, then the screen diagonal and projector position are found to be approximately the same (withing a few inches). Thus, with the proejctor behind you, that would place the seating position at less than 1x the screen diagonal measurement. I always thought 1.5x was the minimum seating distance to avoid seeing the screendoor?

Perhaps brainchilds home setup wasn't using the 320mm lens that I believe is used in the plans.

Thanks in advance for the info.

I run my projector in 16:9 which gives us about a 10' seating distance. My projector is mounted on a side wall so some people end up sitting to the side of it as well.

So what is the actual projector distance? Also, what is the screen size at this distance?

Sorry for all the questions, but I'm really keen to start my first DIY PJ project, but if the throw distance is not going to work for my particular room setup, I may have to consider some alternatives such as a commercial PJ (not anywhere as much fun or as satisfying!)

One final question, the LCD that I have gotten my hands on (free of charge!) is a 800x600 display. I know that the performance will not be as good as an XGA screen, but do you think it will will give reasonable quality?

TIA

Hmm 800x600 is the same resolution as the X1 and Epson S1. Reports say these projectors should go over 6' diagonal. What is your room measurement etc?

Brain, the room is approximately 15' by 15'.

Based on both your calculator and the Infocus calculator and assuming a 15" (4:3) LCD gives a 13.77" diag when used in 16:9 mode I get the following projection distances

@6' diag
___X1 (9.9'-11.87')
___Lumenlab 78" (6.5')
@7' diag
___X1 (11.5'-13.8')
___Lumenlab 89" (7.4')
@8" diag
___X1 (13.2'-15.8')
___Lumenlab 100.36 (8.4')

In all cases the X1 places the projector at a place greater than 1.5x the screen diagonal. However, in the case of the Lumenlab projector it looks as if the projector is always going to be closer than the minimum 1.5x seating distance, and hence I would have thought that you would have to sit behind the projector.

I'm probably missing something simple here, but I was under the impression that folks were placing their lumenlab projectors behind their seating position.

If I can get similar performance out of a lumenlab 800x600 projector that is possible from an X1 than I would be over the moon!

Thanks in advance for "shining some light" on the matter!

Maybe Im confused with this post, but the veiwing distance isn't based on how far the projector is but rather how far seating is compared to screen dimensions. From what I have read it is best to be seated 2x the screen width for best veiwing so your eyes can take in the entire screen. Anything short of that you would have to move your eyes to see the entire picture. Sorry if you are talking about something else.

Well these projectors do have a relatively short throw, so if you placed the projector at a distance of 15', and considering that the projector is 2' long your throw distance would be 13' giving you a ~12' diagonal picture. I don't know if we sit too close or not, it isn't uncomfortable or too big for us, nor is screen door a problem. There are other ways to set up this projector if you want a farther distance from the screen such as in the example below. The projector is in the box between the front seats.

I guess my point was that is why people mounted theirs on the ceiling because of the shorter throw distance. The seating distance not the throw distance would decide if you were to close to the screen as far as screen door effect correct? Based on some of the posts i will assume I'm older then a majority of the members. Us older guys don't sit in the front row at theaters anymore.

Demographic time:

I'm 40 years old.

Oh geez, here we go... Ahh, what the hell, I'm 27...

and.... we're officially off topic...

43 here

and all my posts here can be removed if you like.