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beamax ?

Discussion in 'Projectors, Screens & Video Processors' started by homethx, Jun 5, 2005.

  1. homethx

    homethx
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    What screen should I use with my sony HS20 projector

    I'm looking at the beamax fixed panel screen(200x119) A-series should I use a high contrast or white screen?

    I really want the high contrast screen what do you think.
     
  2. pmc

    pmc
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    I've got a Beamax A Series and totally recommend it. Great screen and pretty easy to put together. It looks like the worlds biggest plasma when in action. Also had very good experience from Beamax customer service when I had to contact them.
     
  3. homethx

    homethx
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    what projector do you own and is the beamax a high contrast or white one ?
     
  4. Gary Lightfoot

    Gary Lightfoot
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    Why do you want the high gain screen? Do you want a plasma look or do you think you might prefer the cinema look (or is your current screen too dim)?

    With a high gain screen you may suffer from hotspotting (noticably brighter in the center) and anyon sitting away from center will be seeing a dimmer image. If it's just a couple of you wantching from the center, then you won't have that problem though. Your black level will be higher (more grey), so if any of those things are an issue for you, the lower gain (1.3 or less) would be more suitable. How many hours on the lamp?

    Gary.
     
  5. homethx

    homethx
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    The projector only has 12 hours on the clock hardly used the damn thing :(
    been Used with a painted white wall before I boxed it up and moved out.
    This is my first screen so I want to do it right and the other thing is why do high contrast(not high gain) screens exist what type of projector they used for ?I would of thought they suit my type of projector just fine!
     
  6. Gary Lightfoot

    Gary Lightfoot
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    High gain screens are used when the light from the projector is not enough to give you the required amount of reflectance. If you have say 500 lumens coming from the projector, and you want a 15ft wide screen, it's not going to give you a very bright image. A screen with gain will give you extra brightness for those people in the center of the viewing area by channeling that light which would otherwise go to those on the side seating. This is called a viewing cone. Graphs shown with the screen type will show how the brightness falls off towards the sides and depicts a hump in the graph. When it gets to half gain, they will quote a figure of say 45 degrees. Double that for the actual cone. A matt white screen may give up to 90 degrees equal visibility (might quote 90 but unlikely since there is no cone or half gain). In other words, no matter where you sit, you will get the same brightnes as anyone else.

    The higher the gain, the more reduce the cone, and with lamp projectors, the more chance of the lamp being made visible by a hotspot in the middle of the screen. This may not always be the case, but the manufacturers should be able to guide you in screen suitability.

    CRTs tend to be quite dim, so would need a high gain screen.

    To work out if you need a high gain, you divide the screen area in square feet into the lumen output of your projector (not advertised lumens - try to find a real measured figure). For cinema levels, you will be aiming for around 12 ft lamberts or more (up to around 16). For tv/Plasma levels, aim for around 36ft lamberts.

    So, if your screen is 7ft wide 16:9, and the true lumen output is 500, you will have a reflectance level of 18ft lamberts, which is a little more than cinema levels but this will drop as the lamp ages and dims with time so is fine. If you wanted tv levels, then it's too little, so a screen with a gain of 2 would be what you would want, provided there are no other rductions in image quality due to the gain.

    If your screen is smaller than 7ft wide, I would think a gain of 1.2 or 1.3 is more than enough, and a matt white unity gain would be more suitable if you're after cinema levels of brightness (12ft lamberts).

    Hi contrast screens are grey, and they're usefull for use with ambient light. The blackest black you can ever achieve is how bright the screen will look when the projector is turned off. If you have any light at all in the room and on the screen, it will look a dull white, and that is your black level. All space scenes for example will be dull white instead of black. In order to help combat this, a grey screen will give you a bass black which both helps with black level (makes it appear blacker) and helps negate the effect of ambient light. A screen with gain can help reject ambient light in favour of projector light as the viewing cone will not only focus more light back to the source (if it's angular reflective, towards the seating area below the pj), but it will also do that to ambient light so it won't send it towards the viewing area so much. The ideal solution for ambient light is a grey screen with gain. If it's just a blacker black you want (LCDs tend to produce a noticable grey instead of black), then a grey screen will help to do that. It doesn't actulay improve contrast, only 'apparent' contrast (it looks like there's more though in fact there isn't).

    A painted white wall can be surprisingly good - three good coats of matt white will be not far off of a matt white screen, so will be around unity gain (a gain of one). If you currently find this too dim, then you will need more gain. If you find the black levels too grey, then a grey screen will help. If you think youhave a dull image that doesn't produce a black but a dark grey, the a grey screen with gain is what you want. Da-Lite do a 1.1 gain High Contrast Cinema Vision screen which might do the trick.

    Gary.
     
  7. homethx

    homethx
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    Oh my god all bow down to the screen god :eek: thanks for your very informative info on screens.
    I've a lot to learn,oh well back to the drawing board.
    I think I'll phone around and get some screen material before buy anything.

    cheers Gary :thumbsup:
     
  8. Gary Lightfoot

    Gary Lightfoot
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    Well, I hope it was an informative insight into what on the face of it is a very simple thing, but can actualy be more involved than we think! :)

    The most expensive part of a screen is the frame, so if you make your own frame using some wood, you can save a lot of money by just buying the screen material and stretching/stapling it over the frame. White Blackout cloth is a cheap alternative to screen material, but has no gain. Proper material will suit you better if you want some gain, and www.ellie.co.uk, www.drhscreens.co.uk and harknesshall.com sell material, as do Da-Lite and Vutec etc. The material may cost you as much as £100 or more depending on the size and gain requirements. I've some pics of my DIY screen on my web-site (link below) if you're interested.

    Gary.
     

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