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My Optoma H77 lumens

Discussion in 'Projectors, Screens & Video Processors' started by Gary Lightfoot, Feb 6, 2005.

  1. Gary Lightfoot

    Gary Lightfoot
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    After watching a couple of movies tonight, I thought I'd meaure the actual lumens the projector was pushing out. Manufacturers figures are often inflated, and sometimes by as much as 40%, so I thought I'd see what mine was doing with over 60hrs on the lamp - this pj is rated at 900 lumens in high lamp, and around 700 in eco mode.

    Here are my readings (my meter reads lux):

    199 lux in high lamp mode = 510 lumens

    152 lux in low lamp mode = 389.3 lumens.

    So it seems the 40% rule isn't far out, and don't forget to factor the lamp dimming over time, so these numbers will reduce.

    While I'm at it, I'll mention the contrast ratio - this is advertised as 3500:1, where as I measured it at 2300:1 out of the box, and managed to tweak 2600:1 by using colour correction filters to achieve D65 calibration.

    Adding the filters also dims the image, but I'm still getting over 13ft lamberts from my 1.2 gain screen which is how I like it. As the lamp dims over time, I can swap two filters for a single multi-coated equivalent and gain some light back and keep the ft lamberts up.

    Gary.
     
  2. Mark Grant

    Mark Grant
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    Hello Gary,

    What are you using to measure the lumens and contrast, do you have colorfacts or some other calibration software/device ?

    Just wondering as these things interest me since I had my DILA calibrated a while ago. ( only about 500 lumens after calibration but looks great)

    Mark.
     
  3. Gary Lightfoot

    Gary Lightfoot
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    Hi Mark,

    I use Colorfacts for colour calibration and extracting image data), and a light meter for lumens and contrast. The light meter tends to be more accurate at reading lower light levels than CF does, though the results are usualy similar if CF can get a good black reading (put the sensor closer to the pj). I initialy used SMART and that has an Extech light meter, but you can buy a Robin RT24 over here for very little on ebay. I got one for £14 to compare it with the SMART meter, and they're the same. It's quicker and easier using the light meter than CF because you have to set up the laptop and sensor for CF. I can take readings by the time I've done all that. :)

    Gary.
     
  4. KraGorn

    KraGorn
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    I take it you didn't take readings when it was new? I'm wondering what sort of brightness loss will occur over time, mine's now well over 100 hours.
     
  5. Gary Lightfoot

    Gary Lightfoot
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    This was at 60hrs, so not far off a new lamp, but I've heard of figures around 10% after 200hrs I think it was. I don't know for sure though.

    Gary.
     
  6. KraGorn

    KraGorn
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    I wasn't sure over what sort of usage a drop in lumen output was usually experienced and whether after 60hrs there'd already have been a noticeable drop.
     
  7. Gary Lightfoot

    Gary Lightfoot
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    I know what you mean - how many lumens a new lamp has with 0 hours on it, and then measure it to see how the lumens drop over time, but I wouldn't expect a 40% drop in just 60hrs though.

    I wonder if they measure the lumens without the colour wheel in place - that would certainly make a difference.

    Gary.
     
  8. Mark Grant

    Mark Grant
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    Hello Gary,

    Thanks for the tip about the Robin RT24 light meter, I bought one on ebay for a reasonable price :)

    There a few more on ebay should anyone be interested. ( dont bid like crazy, more keep appearing)

    Mark.
     
  9. Gary Lightfoot

    Gary Lightfoot
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    Glad you got one at a good price. :)

    I think I bid on a few before I managed to get one at a reasonable price. I didn't want to spend too much because I wanted one as a comparison, but they're a bragain if you get one for under £25.

    You probably already know, but if you want to convert Lux to Lumens, just multiply by 2.561. To find out your ft lamberts, divide the lumens by the area of your screen (width x height in square feet), and multiply by the screen gain. CR is obvious.

    Do you still have the Davis, or have you upgraded yet? My HT1000 is up for sale if you're interested. :D

    Gary.
     
  10. Mark Grant

    Mark Grant
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    Hello Gary,

    I sold that ages ago, the new owner is happy :)

    Now have a second hand (bargain import) JVC DILA , William Phelps flew over last June to calibrate it and a few others :)

    Looks nice :D

    Mark.
     
  11. Gary Lightfoot

    Gary Lightfoot
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    How much does Wm charge for a calibration (PM if you like, and if you don't mind me asking)? What did he do and do you have any results? He's almost legendary over on avs (almost as legendary as Gordon is over here)!

    Gary.
     
  12. Mark Grant

    Mark Grant
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    Sent you a PM Gary :)

    I doubt Wm does Optomas :D

    With a DILA Wm can double/ treble the contrast on the old models, with amazing low level detail, perfect greyscale and fantastic colours.
    Lumens are lower of course, but still plenty left, about 500 on mine if I remember correctly.

    Not a cheap calibration, but without doubt worth every dollar.

    Used DILA's can be found for $1200 upwards, a bargain even though they sound like a dyson.

    If I had the cash I would buy a HD2K and ask when william could call again.

    Mark.
     
  13. Gary Lightfoot

    Gary Lightfoot
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    Hi Mark,

    I've replied to your PM - didn't realise you'de replied here, as you've answerd some questions I'd put in the pm. :)

    I won't be getting WM over - I do my own claibrations! Even so, I would love to have met the man. What was he like? I don't think the cost wasn't excessive considering who and what you got for the money. How bigs your screen and what gain is it by the way?

    Gary.
     

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