I thought this was important enough to start it own topic.

You ask for more light, here it is Venture has a new line of MH lamps that could really give our PJ the brightness in our pictures that where looking for without a reflector.

http://www.venturelighting.com/LampsHTMLDo...lamps.html#875W

How big is the arc?

Jikes, that wattage might jack up the electric bill.

If you go through the site they have various MH lamps between 400 and 1000watts

while 100,000 lumens might initiall sound good, here are some POTENTIAL problems. No One has fully tested a bulb of that wattage yet (A member is currently working with a 1500W bulb, but isnt finished with the build)

1) The center arc length/size. Doesnt do us much good to have more brightness when the collected arc wont fit inside the triplet (possibly could end up with more extreme dim corners)

2) Heat dissapation, that sort of wattage puts out alot more heat. Gotta

3) There could be sooo much light behind the LCD that an over-saturated washed out image may result

These are all potential situations that could arise from using a bulb of that caliber. Not set in stone.

They also have a new lamp the "natural white 950 lamp" A 5000K lamp with a great color. part #24963 775 watt

I've read that dimming a MH bulb will decrease the life of the bulb quite drastically in some cases where the bulb is turned down too much. I believe reading the 60% is about the maximum amount a MH bulb should be dimmed... I gotta see if I can dig up that link...

These bulbs arent made to burn horizontally.

arc length is listed as 81.5 mm and I seem to remember reading in a thread that someone calculated that anything more than 41 mm or so arcsize is max for the standard triplet...don't know about the new pro lens though....

I think we could maybe go bigger than 41mm but NOT much ......

A perfectly ideal situation, then projected arc image at the triplet would be exactly the same size as the physical arc at the bulb, however it isnt. The fresnels introduce sort of a magnification factor. How much magnification is unknown exactly, and definatly dependant upon alignment of fresnels. Its guestimated somewhere around 1.5. The 80mm triplet size, will warrant you to desire a projected arc of 65-70mm.

Starting with 81.5mm, means the projected arc is going to around 120mm. Definatly needs a much wider triplet, or the corners will be really dim, and lots of collected light will be wasted.

I considered these higher wattage bulbs, but unfortunately the ED28 formfactor only goes up to 400 watts. I think the formfactor is important for a horizontal mount and the smaller acrsize.

If they start putting higher wattage bulbs out in the ed28 formfactor then they have something that will benefit us tremendously.

youll just have to mickey mouse it so i will fit. I was able to fit a et37 bulb in my enclosure, the mogul base just stuck out of the enclosure a bit more than it did with the ushio. And you can double up on the lexan to block the extra heat. But the electricity bill will suck.

Andy its not the physical bulb size that is the problem.

its the center tube that produces the light .... if its TOO big, then it will not fit inside the projection triplet, and when it doesnt fit in there, then ALOT of light is lost, and it aids significantly in dimmer corners/ect

hmmm... I think the new pro lens is 100mm? so still too small for this bulb...know anything about the 135mm triplet at diyprojectorcompany? think that would fit this bulb? twice as many lumens as the venture ed28 which seems to be the reigning king of brightness here.... you'd really need a hot mirror or IR glass though ;-)

Yeah, I thought about the larger triplets, but they all have their issues with focus and what not. I heard you could get good results from the DIYPC 135mm, but you have to take it apart it retune it or something

Obviously, if the larger triplets get their issues fixed, then larger bulbs become a viable option. However the problem with the heat, and possible too much light saturation through the LCD will still exist.

I think the 135mm problems are only if you want to use a 17" LCD. the cooling problem could be fixed with a 2 fan cooling system I'm pretty sure(one dedicated to the LCD only) which would leave light saturation...by this do you mean washing out of the picture/lessened contrast?

Not sure if the extra heat can be solved just by throwing another fan it at it. these bulbs give off alot of heat, and arent very effecient with the 400W they consume. The effeciency of a 875W bulb is probably considerably worse, meaning that it will disspate more than 2x the heat as you would expect.

Even then the direct heat from the bulb, isnt the problem. Its the heat on the LCD due to the LIGHT passing through it. Maybe it could be resolved with an additional fan, maybe not. Cant say with any experience

As for the light saturation, yes I meant the washing out of the picture. This was a seriously debated topic a long time ago, where no conclusions were able to be deduced untill someone did it The guy thats making the 1500W pj says he didnt see any saturation, but hes only publically mentioned that hes examined the blue "No signal" screen.

My thoughts, is that there has to be a limit at both how much light can go through the LCD, and what it will look like when it does. Most people prolly wont disagree that that limit exists, the problem is WHERE it exists. Does it exist with a 100,000 lumen bulb behind.

I believe a washing out will occur with bright colors. NOT WHITES, but bright colors. Thing of watching an outdoor scene that shows alot of the sky. Sometimes the Sky is a very bright blue. I think if there is too much light behind the LCD, then this blue can be washed out and appear brighter than it should. Obviously for white and blacks the bigger bulb may not be a problem. so by definition the Contrast ratio may stay the same or even improved. But that does not mean colors inbetween the blacks and whites dont end up looking poor.

Alot of people have said that a larger lamp might wash out the colors but just like what we are using now with our PJ's because the picture is not bright enough we crank up our contrast and brightnessand then adjust our gamma and saturation to get a managable picture,to me if the lamp is to bright why not lower these settings.

I now when I started this post it states 875w with dimming but this site has different size lamps the one that Im going to get is the 725w MH and this lamp works in a horizontal position they also have a 450w lamp that put out 12000 more lumens then the reg 400w that we are using keep in mind these are DIY projectors and I'm for sure Brain went through alot of lens,lamps,monitors and other type of equipment before he reach the point where he was saticfied. He has done a wonderful job but he still left room for use to experiment with his design, look at Punisher, Tescorp,SamuariJack and all the other who has inspired use to do something different , just answer this has anyone tried or know of someone who has tried to use a 1000w MH and what there results where if so that should be the only one giving input.I keep hearing there cuold be a problem with heat,yes it could be a problem I told that same issue with the light tent which I have and the temperture at my LCD never gets higher than 6 degrees above room temp my basement usally stay at 70 degrees. To those of you who want to try something new unless someone here has trid it and giving you advise that it wont work if you can afford the risk take the chance, if it wasn't for chance we would be on this site.

To Rudolph, Is the 775 lamp the Venture #24963? That lamp was listed as experimental but part of the 950 line. If you look at the color spectrum all the 950 lamps make 3 times more red than the standard eye lamps. If you look at the spectrum of the xeon lamps that the pro projectors use they all make way more red. Their spectragraphs are fairly close to the 950 lamps.
The reason a lot of the screen shots look green is becouse they are. I am collecting the spectragraphs of the most common lamps that everyone is using and they all make at least two times more green than red. They may make more lumens per watt but that means nothing if after you white balance and cut the green by 50% to make it look good.
I will be starting a thread in a month or two and post my results.
Everyone said we could never keep a 100 watt cpu cool either. I am sure we can use a lot more light. I think the only real limit is the color filters will wash out but we could add more filters, then add even more light. the real limit is the wall plug.

The biggest problem to hurdle is the arc size ..... if you cant get your beam inside the triplet then there are problems, thats a fact

the other stuff about color saturation and heat, are possible and very likely problem areas. Nothing is unsolvable, it just comes down to what it takes to solve it, and ultimatly, HOW MUCH?

This is DIY, so all solutions have to be dirt cheap ......

arizona here are the spec and # for that lamp

#3940 MH 750W/U/LU/BT37 S111/E BT37 Mogul (E39) Clear Universal 72000 46800 12000 4000 65

The 4000 is the same color as the MH that we use now in our projectors