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Rear project vs. front projection

Discussion in 'Televisions' started by KraGorn, Sep 2, 2003.

  1. KraGorn

    KraGorn
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    Being a n00b to all things home-cinema-ish I'm scouring for info, I've found a good amount on plasmas and front projectors but not much on rear projection.

    Can someone point me at info comparing front and rear systems to give me an idea of their pros and cons. For instance, the up-coming 51WH36 seems to be a pretty awesome piece of kit but how would that compare to, say, an AE300 roughly the same price?

    I also haven't found any info at the moment on just what tech. rs systems use, whereas I have a fair idea of LCD/DLP/ALiS tech. for fs systems.

    Appreciate any links to further reading.

    Cheers.
     
  2. STOWITBELOW

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    I've no idea about projectors, other than you can have a BIG picture. I have a 50" sony (rp) & the picture quality in low light I consider is better than a same sized plasma. However it's poor in daylight, & invisible in bright sunlight. If I'm watching in the evening I don't think theres much to beat it for the money, but don't bother for daytime viewing unless you like the curtains closed!
     
  3. KraGorn

    KraGorn
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    I have a 28" Tosh TV for TV viewing, what I'm looking to do is set up some sort of "home cinema" for DVD viewing. To that end a 50" rp is obviously a LOT more affordable than a plasma.

    My problem at the moment is a lack of technical understanding about how RPs work. I know about plasmas, how they work, what there strengths/weaknesses are, same with FPs and the issues with LCD/DLP etc. I'm hoping someone can point me at where I can read up about RPs and their little foibles.
     
  4. nathan_silly

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    There's two types of Rear Projection...

    1) CRT. Three tubes are stacked vertically, the image is then reflected by a mirror onto the frensel screen. Look here for pictures..
    http://www.bus.ucf.edu/cwhite/theater/Duvatyne.htm

    Each CRT/Lens needs adjusting. You have the electronic focus which focuses the electron beam onto the CRT (this is just below the lens) Electronic focus is done by looking directly into the lens and adjusting the FOCUS pots behind the speaker grille.

    The optical lenses will also need focusing to achieve the best on screen image. Then convergence. This adjusting the on-screen convergence grid each CRT points to the same place (if they don't you get overlapping of colours)

    CRT has the pros of the best picture quality- good black level, filmic PQ (over LCD & Plasma) but has some cons like focus, geometry, convergence of three lenses & three CRT's- and requires occasional dust clean/mirror/lens & reconverging, and scren burn.

    CRT RP requires a technical level of mind to get the best PQ out of it. It still looks very good out of the box (do the user level convergence and it PQ increases- although the best PQ is achieved via service level convergence)

    -----------------
    2) LCD Projection
    A LCD projector (imagine say a Panasonic 100 vertically)- image is reflected in the same way as the one above to the screen)

    Pros are simple image optimisation- only needs single lens optical focusing and geometry, no chance of screen burn. Cons are poor black level, LCD pixel death, LCD panel heat soak, noise/heat from fan & bulb. More prone to dust (as the unit sucks in air)
     
  5. KraGorn

    KraGorn
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    Thanks for the overview Nathan and the link .. helped my education a lot :).

    It seems from what you say therefore that LCD rps, aside from the different means of projection, have the same characteristics, strength and weaknesses as their fp counterparts with repsect to image quality, resolution, ratio etc.

    You make the CRT rps sound very fiddly to setup and maintain, is it just that there are a few simple steps needed or is it really somewhat complex?
     

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