Originally my PJ was as follows [ 400w MH > 220mm frez > 10.6LCD > 550mm frez > 18" beseler]
It had a 16ft throw, and was pretty good. Id like to change things up for the rebuild. Im thinking of building it into a coffee table, which would shorten the throw to only 9ft. I have a few questions before i move forward with this idea. Will i gain some brightness by moving it that much closer? With the lens being roughly 9ft from the wall, and the bottom of the image being roughly 1.5ft above the floor, will i have much keystoning issues at this angle? This is the new setup im thinking of using, im wondering if you guys think ill run into any problems. It will be as such: 400w MH > 220mm frez> 10.6LCD > 317mm frez > LL s15 triplet (320mm focal range right?) According to the FocalCalc it should give me a screen that is 85.44". On a 10.6LCD, what does that equate to in length and height?

Brightness (lux) is equal to lumens divided by the screen area (in square meters)

If you decrease the area of the screen by 1/2, you should get double the brightness.

Decreasing the screen by 1/2 is reducing it to 71% of it's diagonal size. So if you had (As an example) 100" diagonal before, and you reduce that to 71" diagona, you'll have 1/2 the surface area, and therefore double the lux.

Throw doesn't factor in, except in screen size.

If you change out the projection lens for a shorter throw, that changes the size. Same size, assuming the same interal efficiency in getting light to the projection lens, you'll have the same brightness.

That's an awful lot of keystone correction... you can work it out yourself, but I'd say that's probably more than will work well.

Edit:

For the "What does that equal in width and height" I'm feeling too lazy to punch in those nunbers myself, but read the FAQ. The 10.6 (1280X768) is a 15:9 aspect ratio screen.

ah ok, i wont bother then. I was only gunna do the floor version, because i thought that if it were closer, id get more brightness out of it. I was aiming for the same screen size either way. I guess ill just redo my old setup.