ANSI Lumens on DLP Projectors

Discussion in 'Archived Threads 2001-2004' started by Murray Swanger, May 28, 2002.

  1. Murray Swanger

    Murray Swanger Auditioning

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    Any experience with DLP front projectors. Have had some tell me to get 1100 ANSI or more, up to 2200.

    Had another source tell me that is overkill for a home theater system. That 800 is more then enough.

    Any thoughts would be appreciated.
     
  2. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    Unfortunately, there is no clear cut minimum lighting. It depends on a lot of variables.
    I've found this to be the most helpful guideline:
    With perfect or near perfect ambient lighting control (ie. watching in a basement with other lights off), you want between 12 and 18 ft-lamberts (THX certification specifies 16fL plus or minus 2fL). Most modern theaters where you notice a bright and punchy picture tend to have 12 ft-lamberts at the very least.
    http://www.thx.com/professional_services/guidelines.pdf
    I personally do not have a dedicated theater with that kind of lighting control. With very good (but not complete) ambient lighting control, I think you'd want at least 20-25 ft-lamberts. With a superbowl party (who watches with the lights off?) you're going to want close to 30 ft-lamberts.
    To find the ft-lamberts, this is what you do (I'm going to use my 3000 ANSI lumen XGA native Proxima DP8000, just as an example):
    Take the total ANSI lumens of your projector when new (3000 lumens)
    Decide whether or not you're going to calibrate that projector. Most likely, the answer will be yes. Projectors tend to lose upwards of 30% of their illumination during calibration... my guestimate. Some will lose dramatically more, some will lose dramatically less. (2000 lumens)
    If your projector is natively 4:3 format, for instance 1024x768 or 800x600, you'll lose 25% of the illumination if you project a 16:9 image, given you do not us an anamorphic lens. If you have a 16:9 projector, you don't have any loss at this point. (1500 lumens)
    Divide this number that you have with the number of sq feet your screen is. For instance, a very reasonably sized 135" diagonal 16:9 screen is just over 54 square feet. (27.8 ft-lamberts)
    What we have here is 27.8 ft-lamberts with a BRAND NEW bulb. Most bulbs (NSH, UHP, SHP, P-VIP, Xenon) tend to lose illumination quite quickly. They reach a 15-20% loss rather early in life, and when near the end of their useful cycle, reach about a 50% illumination loss. Thus, in this example, we're going to get:
    27.8 ft-lamberts when new
    22.2 ft-lamberts when 20% loss
    13.9 ft-lamberts when lamp is nearly dead
    Also, as a general rule, at a given brightness (say, 1000 ANSI lumens for example), D-ILA/LCOS projectors tend to appear the brightest, followed by LCD, and DLP's tend to look the dimmest.
    Let's now take the example of an 800 ANSI lumen DLP. Let's say when calibrating it, it only loses a very VERY slight 10%. We're down to 720 ANSI lumens. Is it 4:3 or 16:9? Let's say it's 16:9 so that it loses no illumination... we're still at 720 ANSI lumens. Let's take the same 135" diagonal 16:9 screen.
    With a brand new bulb, with this 800 ANSI lumen projector, we get 13.3 fL. Let's say that the bulb is absolutely incredible and only loses 10% of its brightness (none do) initially, and only loses a scant 25% of its brightness when the bulb is near dead (good luck). This is what we get:
    13.3 fL with brand new bulb
    12 fL with 10% loss
    10 fL with 25% loss
    If this was a 4:3 native projector instead of 16:9, we'd have:
    10 fL with brand new bulb
    9 fL with 10% loss
    7.5 fL with a 25% loss
    Pretty ideal conditions, but pretty dim, eh? I guess you could fix it by using a tiny screen. Is it worth it though?
    Oh yeah, 1 more thing. The brighness can be improved by using a higher than unity gain screen. The image quality (and specifically contrast) from all digital projectors benefit from using some sort of gray screen, which tends to decrease the perceived brightness. If you want to spend the money, you can get a screen that improves the perceived contrast yet is still higher than 1.0 gain, like the Stewart Firehawk. It has a 1.35 gain. It's expensive, but if you have a lower powered projector, it's probably worth it. So an image that would be 10 fL, would be 13.5 fL with this screen.
     
  3. Murray Swanger

    Murray Swanger Auditioning

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    Impressive response and thanks very much. Based on your information, the "home theater" product from Plus called a Piano will not meet my needs. New, it only has 700 ANSI Lumens. Not sure where this type of product would fit in the market. I guess for those who only want a small screen, but then why buy and expensive projector.

    Thanks again for the help
     
  4. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    No problem.
    BTW, the Plus Home Theater Piano HE-3100 has 450 ANSI lumens (I'm not sure if they have a new, more powerful Piano).
    Plus Piano HE-3100
     
  5. brian__pratt

    brian__pratt Agent

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    No experience with home use on this...but the InFocus LP790 (3000 Lumens) is extremely bright...visible clearly in full overhead office lighting. It appears to be almost TOO bright in a dark room (opinion, of course). DVD playback on it is impressive, but is mainly for conference room work (PowerPoint, etc).

    .02
     
  6. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    The Proxima DP8000 and Infocus LP790 are the same projector (as with the ASK C300). It's a good choice for large screens (especially gray screens like the .8 gain Dalite High Contrast DaMat) and living rooms.
     
  7. Murray Swanger

    Murray Swanger Auditioning

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    Thanks for the clarification on the 3100 with 450 Lumens. Their new model is officially out in July with 700 Lumens. Spoke with a Plus rep who was helpful but made me nervous when he said 700 was plenty for home use.

    Based on your feelings, 400-700 Lumens would not be enough unless I was able to keep all light out of the room., I have 2 kids so I don't see this working.
     
  8. Murray Swanger

    Murray Swanger Auditioning

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    What about this model from Plus:

    U3-1100ZW
     
  9. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    As far as I can see (and I can be wildly off), the new Plus Piano HD-3200 which will be out at the end of July still has 450 ANSI lumens:
    http://www.plus-vision.com/jp/news/2...29_he3200.html
    [​IMG]
    There's a bit shorter throw distance (new zoom lens) and also 480p/576p/1080i/720p component input. Oh yeah, 2 new colors. I don't see a difference in contrast or brightness though. Projected cost is about $3200 or $3300, just a tad more than the HE3100.
    In all fairness, they could be speaking of another Plus Piano launching in July.
    The U3-1100ZW is one of their business projectors:
    http://www.plus-vision.com/en/produc...100z/spec.html
    1100 ANSI lumens
    650:1 on/off contrast
    DLP - unpublished colorwheel speed
    XGA (1024x768) native
    No DVI input
    130 watt P-VIP lens
    Personally, I think the U2-1110 makes a better case for itself with 800:1 on/off contrast (same 1100 lumens). Again, no DVI though.
    At this price level, why not consider the HP XB31 (XGA native, 1500 lumens, 1800:1 contrast, slow 2x colorwheel, DVI)?
     

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