I've been a reader of this forum for a while and the general consensus seems to be that "more is always better" when it comes to light output.
At least for OHP/Panel applications, I'd like to challenge that idea.
LCD Panels are low contrast devices, usually rated at 100:1. Compare this to today's comercial projectors at a minimum of 400:1 up to 3000:1...
The low contrast ratio means the darkest pixels aren't truly opaque, and don't block out 100% of the light. The result is that black doesn't look black, instead it's a dark gray.
My thinking is that a stronger light behind the panel will produce an even lighter gray for your blacks - which is highly undesireable.
I have a Buhl 2900 (5500 lumens) and a Dukane 680 (7800 lumens). I actually prefer the Buhl for my application, and I've never had a problem with overall light output. The whites are nice and bright... and when the screen goes white from an explosion or something it's bright enough to make my eyes squint...
So if I go brighter - ok, maybe my eyes will squint *more* - but at the cost of my dark scenes not being as dark. I don't think that's an acceptable sacrifice.
I think a better approach for brightness would be to go with an OHP that is *only* as bright as it needs to be to acheive your minimum brightness preferences for your particular application... and no brighter!
With our low contrast ratios... I think the light output of the OHP is a major variable in a delicate compromise.
If during a bright scene you go "ahhh, that looks nice," but during a black scene you go "man, that looks like crap..." consider going with a lower output OHP. Sacrifice a little brightness for better darks.
(PS - One of those high-contrast gray screens would be super cool for an OHP/Panel combo... go a little higher on the lumen output for the same whites and darker blacks.)
At least for OHP/Panel applications, I'd like to challenge that idea.
LCD Panels are low contrast devices, usually rated at 100:1. Compare this to today's comercial projectors at a minimum of 400:1 up to 3000:1...
The low contrast ratio means the darkest pixels aren't truly opaque, and don't block out 100% of the light. The result is that black doesn't look black, instead it's a dark gray.
My thinking is that a stronger light behind the panel will produce an even lighter gray for your blacks - which is highly undesireable.
I have a Buhl 2900 (5500 lumens) and a Dukane 680 (7800 lumens). I actually prefer the Buhl for my application, and I've never had a problem with overall light output. The whites are nice and bright... and when the screen goes white from an explosion or something it's bright enough to make my eyes squint...
So if I go brighter - ok, maybe my eyes will squint *more* - but at the cost of my dark scenes not being as dark. I don't think that's an acceptable sacrifice.
I think a better approach for brightness would be to go with an OHP that is *only* as bright as it needs to be to acheive your minimum brightness preferences for your particular application... and no brighter!
With our low contrast ratios... I think the light output of the OHP is a major variable in a delicate compromise.
If during a bright scene you go "ahhh, that looks nice," but during a black scene you go "man, that looks like crap..." consider going with a lower output OHP. Sacrifice a little brightness for better darks.
(PS - One of those high-contrast gray screens would be super cool for an OHP/Panel combo... go a little higher on the lumen output for the same whites and darker blacks.)
this is an idea i shared with the guys on here a little while ago. Lifter almost tore me a new one.
I believe what you are saying is true. higher power lamps will change the contrast on the screen (i believe). unfortunately no one has tried this to be certain. A good comparison would be a 250 W MH & a 500W or 1000 W MH and the same LCD panel.
ap0
I believe what you are saying is true. higher power lamps will change the contrast on the screen (i believe). unfortunately no one has tried this to be certain. A good comparison would be a 250 W MH & a 500W or 1000 W MH and the same LCD panel.
ap0
brighter lamp = brighter everything
brights are brighter
darks are brighter
if brights can be darker and still be acceptable, go with a light that's not as bright... and get your darks darker
At 100:1, it's a struggle to get dark darks
AT 3000:1, I imagine black = virtually opaque, so maybe "more *is* better" for that setup
brights are brighter
darks are brighter
if brights can be darker and still be acceptable, go with a light that's not as bright... and get your darks darker
At 100:1, it's a struggle to get dark darks
AT 3000:1, I imagine black = virtually opaque, so maybe "more *is* better" for that setup
I think if you're working with an LCD Panel/OHP... that this is your ideal scenario:
Completely darkened room.
High-contrast gray screen.
OHP in a sealed box.
OHP lumens sufficient to produce minimally acceptable brightness levels - but not any brighter.
Completely darkened room.
High-contrast gray screen.
OHP in a sealed box.
OHP lumens sufficient to produce minimally acceptable brightness levels - but not any brighter.
I agree, more brightness will reduce your contrast. But the High lumen race is for Daytime viewing...These guys are trying for a day time viewable projector.
Hmm... A projector that you could watch at high noon outside on the beach! Wow. Actually, i think the bottom line is that projectors are not made for day time viewing, and if you still want to watch moiew during the day, buy some blackout cloth you can drap over your windows to seal out all the light. If some one does make a 1000 watt metal halide projector that works for daytie viewing, i will be impressed 🙂.
Not high noon, but i remember a post by someone on here who had just gone to a drive-in theater and wrote about how impressed they were that there was so much external light at the drive-in (i guess light posts and concession stand lights and whatever...this guy was saying it was super bright with all the lighting around) and yet you could still see the screen very well.
Verbose: I agree! No matter how bright your projector is, your darkest black can only be the color of the screen. Seal off those windows!
Property... I'll bet the reason the screen still looks good at a drive in is that, although there is a lot of lighting all around, the distance between those lights and the screen is considerable - like 50 feet something like that. Add that to the fact that the environment is not a sealed box, like your room, where reflecting surfaces will carry a lot of the light to the screen.
Ambient light won't lighten the darks on your screen if it never reaches your screen... but even the tiniest light in your living room reaches the screen - since it's only 12 feet away and there are a lot of reflecting surfaces. Doesn't help that your walls are (probably) white!
Property... I'll bet the reason the screen still looks good at a drive in is that, although there is a lot of lighting all around, the distance between those lights and the screen is considerable - like 50 feet something like that. Add that to the fact that the environment is not a sealed box, like your room, where reflecting surfaces will carry a lot of the light to the screen.
Ambient light won't lighten the darks on your screen if it never reaches your screen... but even the tiniest light in your living room reaches the screen - since it's only 12 feet away and there are a lot of reflecting surfaces. Doesn't help that your walls are (probably) white!
You know, I've got a 250W MH Elmo Solar that I bought by accident, thinking it was a "deluxe." I should try it in a completely darkened room and compare it to my 575W Dukane 680...
I've got a relatively short throw to the screen (7' image width) and I believe my screen is a high gainer, so it just might do the job.
One reason I never even tried the Elmo is that the upper reflecting mirror broke during shipping. Anyone know if I can just get a new mirror cut at a glass shop, or does it have to be some sort of special "optical grade" mirror?
I've got a relatively short throw to the screen (7' image width) and I believe my screen is a high gainer, so it just might do the job.
One reason I never even tried the Elmo is that the upper reflecting mirror broke during shipping. Anyone know if I can just get a new mirror cut at a glass shop, or does it have to be some sort of special "optical grade" mirror?
I only use my 150watt projector in a darkened room and project onto a white screen. I am happy with the overall brightness of the scenes but do notice that the blacks are lighter than the shadows that are cast by the panel frame blocking the light. The contrast on my panel is only 100:1 so I may try a grey screen to improve the blacks. I currently project a 75" screen because thats how big thew frame I made is and the OHP sits on a table in the room, no need to re arrange anything.
Alchemist... with everything else staying the same - I expect the gray screen will reduce your brights. (The adverts for some gray screens say it won't but I don't believe it!) So it may then be necessary for you to bump up your lumens a little bit.
Thanks for the post, and that's another good point that I kind of glossed over.
closer screen = smaller image = less bulb power is necessary
I still say, regardless of your OHP/panel setup, choose your OHP carefully the achieve your minimum brightness preferences - but don't go over, or your darks will suffer.
Thanks for the post, and that's another good point that I kind of glossed over.
closer screen = smaller image = less bulb power is necessary
I still say, regardless of your OHP/panel setup, choose your OHP carefully the achieve your minimum brightness preferences - but don't go over, or your darks will suffer.
You need a surface mirror. One should not be too hard to find online at surpluss shop you could cut to size yourself... Maybe even a glass shop can cut one for you. There are also places that sell ohp parts such as www.kmr.com , though they are quite costly.
Actually called a front-surface mirror as opposed to normal mirors which i suppose are called "rear-surface" mirrors.
Yes, as Apothesis will tell you, this has been discussed before. The key thing to not confuse the color of your black levels with the work "contrast". Contrast means exactly that. It is the difference between dark and light. A brighter light does not affect this as far as the LCD is concerned (it's a different story with the screen).
Schmanthony, your absolutely right when you say that brighter light means darks are brighter, and whites are brighter. However, this does not change the difference between the two.
Lets upgrade from a 100W bulb to a 400W bulb. Oh no! What was once a semi-dark black now looks grey! And the whites are blazing hot! What to do?
There's this control you have on your LCD where you can adjust your contrast level. All you need to do is lower this setting and your blacks will be just as black as they were before, and your whites will be where they were before. Same color, but a brighter picture.
More light = a good thing.
A higher contrast ratio = a good thing.
Schmanthony, your absolutely right when you say that brighter light means darks are brighter, and whites are brighter. However, this does not change the difference between the two.
Lets upgrade from a 100W bulb to a 400W bulb. Oh no! What was once a semi-dark black now looks grey! And the whites are blazing hot! What to do?
There's this control you have on your LCD where you can adjust your contrast level. All you need to do is lower this setting and your blacks will be just as black as they were before, and your whites will be where they were before. Same color, but a brighter picture.
More light = a good thing.
A higher contrast ratio = a good thing.
Except... the panel can only produce a certain level of opacity. I'd think you'd always have it set to be as opaque as possible at true black. Why have it any less opaque?
So, at 100W, I'm producing maximum opacity. The panel cannot go any darker.
At 400W, the darks are going to be brighter, and there will be nothing I can do about it. Fooling with the panel's contrast will change the image, certainly, but it won't make the black pixels any darker. It's just going to make more of the *lighter* darks darker... and more of the lighter lights lighter, if that makes any sense. (I'm starting to sound like Dr. Seuss.)
So, at 100W, I'm producing maximum opacity. The panel cannot go any darker.
At 400W, the darks are going to be brighter, and there will be nothing I can do about it. Fooling with the panel's contrast will change the image, certainly, but it won't make the black pixels any darker. It's just going to make more of the *lighter* darks darker... and more of the lighter lights lighter, if that makes any sense. (I'm starting to sound like Dr. Seuss.)
Yes, the blacks are brighter, but so are the whites. Therefore, it does not affect the color range because the difference between the two is the same.
Literally having dark blacks is not the benefit of having a good contrast ratio. The benefit is to have a more vivid color range. If you just want your bright blacks (dark greys) to look dark black, use a grey screen with a lower gain.
Literally having dark blacks is not the benefit of having a good contrast ratio. The benefit is to have a more vivid color range. If you just want your bright blacks (dark greys) to look dark black, use a grey screen with a lower gain.
Hehe why not just use a lower wattage bulb?
I see what you mean about contrast ratio not being directly affected by changing to a brighter bulb... and in fact I never argued that it did.
The way I feel about light intensity is... it's *enough* if white looks white, and the picture is bright enough for your tastes.
If you go any brighter with your bulb, then sure, your whites are brighter... but they were already bright enough!
And now your darks are also brighter, and that's *not* good. You've killed your darks for better brights... when you were happy with your brights to begin with.
I think, for a given setup... where the only changing variable is OHP light output, there is an ideal light output. Going lower will result in a overall dark image. Going higher will wash out your darks.
I see what you mean about contrast ratio not being directly affected by changing to a brighter bulb... and in fact I never argued that it did.
The way I feel about light intensity is... it's *enough* if white looks white, and the picture is bright enough for your tastes.
If you go any brighter with your bulb, then sure, your whites are brighter... but they were already bright enough!
And now your darks are also brighter, and that's *not* good. You've killed your darks for better brights... when you were happy with your brights to begin with.
I think, for a given setup... where the only changing variable is OHP light output, there is an ideal light output. Going lower will result in a overall dark image. Going higher will wash out your darks.
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