How to improve blacks on H77?

Discussion in 'Projectors, Screens & Video Processors' started by Lobo, Feb 14, 2005.

  1. Lobo

    Lobo
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    I have an H77 for demo and am projecting it onto a 9 feet wide section of an off-white wall. The picture is good and the colours in general look good but I think sometimes the picture looks a bit washed out. This is especially during dark scenes where the blacks dont look as black as they should, but more grey.

    Could this be due to my setup in any way? I was thinking it may be due to the large screen size or the fact that Im projecting onto a wall and not a screen.

    Also, would the 7205 improve on this in any way as I believe it is a brighter projector and this might improve the vibrancy of the picture.

    Any suggestions would be appreciated.

    PS. I have a room that I can pretty much black out, although the walls are light. I tried putting some dark sheets on the walls today but this didnt help much.
     
  2. Bristol Pete

    Bristol Pete
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    What are you using to drive the image?

    Denon DVD decks can output a darker or lighter black level which ramps up the black.

    Cap :)
     
  3. RTFM

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    Lobo,

    Did you optimise the picture with Avia or DVE ?

    It doesn't take long to get the black level and white level right. It doesn't really matter whether you choose 0 IRE or 7.5 IRE as long as you calibrate the black and white levels afterwards.

    I have sent you a reply to your PM re. these 2 projectors.

    Jeff :rtfm:
     
  4. Peter Parker

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    Hi Lobo,

    Have you set the white and black levels using a test disk? You should use Avia (NTSC) or Digital Video Essentials (PAL) to do this, otherwise you may have the brightness too high (and/or a high gamma) which will make the blacks lighter than they should be. Use gamma 2 or 3. Depending on your DVD player, the brightness may have to be reduced below zero.

    If you have a THX DVD with the THX Optimode set-up on it, you can use that (THX drop shadow test is for black level - use the pj brightness control), but it's not as good as a proper test disk, as the Optimode is designed for the disk it's on, and can't be relied on as a blanket calibration like Avia or DVE. It might get you closer than you are if your settings are way out though.

    Failing that, you can use an ND2 filter to reduce the lumens by half (equivalent of one full stop), but I think an FL-Day filter (1/3rd of a stop) and colour temp setting 3 would be a good compromise . Use the film mode combined with CT 2 and gamma 2 or 3 for reasonable results otherwise, then calibrate the levels with a test disk.

    Gary
     
  5. Lobo

    Lobo
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    The blacks look good in brighter scenes but when I watch a dark scene, the blacks look a bit grey. Ive calibrated using DVE to get the settings right.

    My room's pretty well light controlled although I have some bright walls and a mirror in the room. Do you think this makes a big difference?

    I remember I got a demo of a Sim2 Domino 20 and the retailer was pointing out how good the blacks were using Dark City, but they still seemed a bit washed out to me. (The guy had a good, totally light controlled setup). So maybe Im expecting too much? How black can I expect the blacks to be?
     
  6. Peter Parker

    Peter Parker
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    Most DLPs will produce a black level better than your local cinema, but not as black as a CRT. Lamp projectors cannot project black so currently you will have to use a filter to dim the image down, but that may effect overall brightness and may make the overall image too dim for you.

    White walls and a mirror won't help your in-scene black levels as the bright parts of the image will reflect back onto the screen and wash-out the dark parts to a degree. They won't effect black on it's own as much though.

    What is your reference for black that makes you expect more from a projector?

    If black is the most important part of the image for you, then you will need to get a CRT projector, but that might have trouble filling your screen as brightly as your H77 currently does unless you get an 8 or 9 inch tubed model. Even then you will have inferior ANSI (in-scene) contrast as CRTs don't do ANSI as well as DLPs do now, and with white walls and a mirror reflecting light, you will have reduced it further. Pure black scenes will be fine though.

    In scene black level is a more frequent occurance than scenes which are black only, so you will have to decide what is more important to you. All projector technologies have their limitations, you just have to decide which ones you are willing to live with.

    Forgot to mention - a grey screen will help improve black level. You then have to decide if you want less or more than unity gain before deciding which one to get, as manufacturers make them from about 0.6 to 1.3 gain. I would think a 1.1 gain will be a good compromise though. The Da-Lite screens have a 1.1 gain screen they call the High Contrast Cinema Vision I think which might do the trick at a reasonable price.

    Gary.
     

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