By that I mean I have yet to see one that projects more than 500 ANSI lumens. What's the deal here? LCD/DLP/D-ILA projectors have no problem.
Why are CRT projectors inherently unable to produce great amounts of light?
- Thread starter Howard
- Start date
You know... that is an EXCELLENT highly technical question. I read a lot of Home Theater Mags... and I'm sure I've read it somewhere before, but I just cannot recall.
I have a projector (LCD) and it pumps out 1000lumens.... and there are some meant for large venue presentions (from computer) that go up to 3000+. Crazy.
So, what's up with the guns. Heat must be one factor. Also, I think that the electron gun hitting the tubes (glass) probably have a limit to how powerful they can be before they etch the glass (burn in) too quickly. Also, CRT's take tons of voltage as it is... a brighter scan would probably require nutso voltages. I guess they could probably make tubes out of high quality glass (lead glass/crystal), but that would be prohibitively expensive. Of course, this is just speculation... so who knows.
I have a projector (LCD) and it pumps out 1000lumens.... and there are some meant for large venue presentions (from computer) that go up to 3000+. Crazy.
So, what's up with the guns. Heat must be one factor. Also, I think that the electron gun hitting the tubes (glass) probably have a limit to how powerful they can be before they etch the glass (burn in) too quickly. Also, CRT's take tons of voltage as it is... a brighter scan would probably require nutso voltages. I guess they could probably make tubes out of high quality glass (lead glass/crystal), but that would be prohibitively expensive. Of course, this is just speculation... so who knows.
The Digital Projection Lightning 25sx projects 14000 ANSI lumens (not a typo) with a native resolution of 1280x1024. The Vidikron Vision One projects 295 ANSI lumens (also not a typo) with a max resolution (being a CRT) of 2500x2000. The Lightning costs $125K, and the Vision One costs $30K.
Hmmmm.
Hmmmm.
Yucky, you have a link for that DPL? That is interesting, I'd like to check that out. Or are you refering to the 3 chip DLP (TI's Digital Light Processor) Professional Cinema system... the one they played Star Wars: Ep. 1 on at select theaters?
Anyway, I just found the Barco BARCOVIEW 812 does 500W ANSI lumens, but with 12" phosphor tubes... Hard to replace.
For anybody that knows about digital cinema, how is it that you can ouput an SXGA (1280x1024) image with an anamorphic lens and not have it come out stretched-looking (or can it be done)? Because a lot of SXGA projectors come with anamorphic lenses, which mean basically nothing if you use it for 5:4 or 4:3...
For anybody that knows about digital cinema, how is it that you can ouput an SXGA (1280x1024) image with an anamorphic lens and not have it come out stretched-looking (or can it be done)? Because a lot of SXGA projectors come with anamorphic lenses, which mean basically nothing if you use it for 5:4 or 4:3...
It was stated above, the CRT has to make all the light you see and will 'burn out' real quick-like.
A digital projector works more like a film unit, with a potentially massive light source. If you've seen a cinema DLP light box (the blue one) it's 6-8x bigger than the imaging section.
I have had the opportunity to see 3 projectors in 2 venues and DLP can look really good. At 1.85:1 (Flat Panavision) it holds up OK at normal viewing distance (not the first 5-10 rows). This is with animation (e.g. Tarzan, Toy Story 2) and live action (e.g. Bicentennial man, JPIII). This is a 1280x1024 panel with the 1.5x anamorphic (standard lens).
At 2.35:1 (Atlantis is the only I've seen) it starts to break up. The movie looked fine, but as soon as the credits started I could see jaggies even from a good viewing distance, about half-way back. My friend didn't see them (he's going blind
until we moved in closer, then he said jokingly "I'll never watch DLP again!". We went up and looked at the unit - it had a second lens installed on the front to get to this ratio, as we had read would be the case.
The point:
The 1280x1024 projectors need an anamorphic lens (if they have square pixels, which they do) since that is 1.25:1.
NTSC is 4:3 or 16:9 (1.33/1.78) and movies are wider: 1.85, 2.2 or 2.35:1
They just scale the source material to fit in that size and optically expand it as needed (like the 1.5x on the DLP I mentioned).
A digital projector works more like a film unit, with a potentially massive light source. If you've seen a cinema DLP light box (the blue one) it's 6-8x bigger than the imaging section.
I have had the opportunity to see 3 projectors in 2 venues and DLP can look really good. At 1.85:1 (Flat Panavision) it holds up OK at normal viewing distance (not the first 5-10 rows). This is with animation (e.g. Tarzan, Toy Story 2) and live action (e.g. Bicentennial man, JPIII). This is a 1280x1024 panel with the 1.5x anamorphic (standard lens).
At 2.35:1 (Atlantis is the only I've seen) it starts to break up. The movie looked fine, but as soon as the credits started I could see jaggies even from a good viewing distance, about half-way back. My friend didn't see them (he's going blind
until we moved in closer, then he said jokingly "I'll never watch DLP again!". We went up and looked at the unit - it had a second lens installed on the front to get to this ratio, as we had read would be the case.The point:
The 1280x1024 projectors need an anamorphic lens (if they have square pixels, which they do) since that is 1.25:1.
NTSC is 4:3 or 16:9 (1.33/1.78) and movies are wider: 1.85, 2.2 or 2.35:1
They just scale the source material to fit in that size and optically expand it as needed (like the 1.5x on the DLP I mentioned).
LCD projectors have a problem with bright output because they block a lot of the light (~1/3 I think). They also have the problem of of lower contrast ratio(1000:1 for high-end(affordable)units) than the DLP's or CRT's, so even if you pump a lot of light through it, the dark colors get washed out.
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