O.K. I posted about this in my PLOG, but I never get any answers there. So here I am in the Tech Support section.

Readings in LUX (not lumen):

12 14 9
12 19 11
12 17 10

So averaged that give me about 12.6 with a screen size: 7.86627 Square Meters.

Is that pretty good? The projector was about 135 inches from the wall, and the screen was 127 inches by 96 inches. Any input would be great. I am thinking that I might need to redesign again if these are really low.

check this out............ post number 5

http://www.lumenlab.com/forums/index.php?s...mp;#entry294131

I dont have a meter so I am clueless

96 lumens .

That's about average for a projector on this site.

I couldn't get that one to work. I posted in that thread about what happened when I plugged my stuff in.



Wait, where did you get the 96 from? Is that what mine is doing in lumens? Also, what size screen is the 96 for?

You have a screen size of 7.68 meters times the average lux of 12.6. Multiplying those gives you your ansi lumen rating of 96.78.

With a Pro reflector you can get it about 50% higher. So almost 150 lumens.

Hmmm I came up with 101 for Windcalmer doing the formula but I dont really know what I am doing I couldn't get the lumen calculator to work.

I had the reflector in when I took the readings. I think it may have been off to one side though. I will take more readings later to see if I can get it more even, and a bit brighter.

What is the exact formula to get the ANSI rating?

Didn't I just tell you.

Average lux (taken from the 9 areas) times the area of the screen in meters.

12.8 was the average lux. The screen size is 127x96 or 3.22mx2.44m=7.86m.

So 12.8x7.86= 100.6

I did the last one in my head so I was a little off

Duh, sorry. I read it and then turned around and asked. Sorry, its been a long day nad I have been going over and over this whole thing in my head since I woke up.

Please dont mind me.

Thanks for the help guys and girls!!! I will post more numbers in my PLOG when I get them.

Yeah, 100 lumens or so is pretty typical. With a good reflector you can bring this level up a bit, but that's about what people should count on getting from a DIY projector. (If you can get more, treat it as a bonus.)

Of course a reflecotr helps, the better the reflector, the better the measurements.

Tweaking the fresnel and lamp placement so that you get as much light as possible into the triplet will also bring up those numbers.

The ultimate deciding factor is your LCD panel. A more transmissive panel can make a world of difference, the problem is that there's no way to know until you strip the panel down. Since the panel blocks MOST of the light that hits is (92-96%) there can be a HUGE margin of difference between one panel and another. One that lets a mere 4% of the light through will give a dim image. One that lets 8 (or more) percent through will have double the lux. (My 17" LCD I measured at 8.9% or some such, giving me a very bright projection indeed.)

Well you do have a ridiculously large projection. 100 lumens doesn't look too shabby when it's a projection half that size (four times the brightness), but you just went all out didn't you?

I'd suggest bringing the projector forward a little or, better yet, get some really good curtains. Human eyes can are very forgiving of low light if, by comparison, the room is even darker.

There's always the hi-gain screen option too. As I've said before when things aren't working just throw more money at the project.

I thought of the high gain screen option, but did you see his projection size? That would be one expensive screen.

Hence the "throw more money" part of my statement.

Agreed... HUGE screen = dim picture. In a totally light controlled environment that would be okay.

There was one fellow here who had 17 (Yeah. Seventeen) lumens, and was actually happy with the picture, since it was in a totally light controlled environment. I think that his image was about 70" diagonal, so it was only marginally dimmer than the OP.

Yeah, I did sorta swing for the fence. I am not going to be keeping it that large. I just wanted to know that I could. So far I can take the screen from 4 feet wide to over 14 feet wide. I built a TON of play in the triplet.

Thanks for the help. I just wanted to make sure that I was within the norm for brightness. I thought that I was given that I was very happy with the brightness even with it huge. I just like to have numbers.

Oh, also these are in my PLOG as well, but I wanted to show how bright it was with daylight pouring through the window:

Do you know where I can read about this plog?? I am just curious as to his setup... light source, lcd size... etc...

Not sure, but I think he's referring to electrodacus's XGA LED projector.

A precondenser would be another way to get more brightness to the screen.

Yeah, I have been thinking of going with a pre-con. I have also thought about stepping up to a larger bulb.