What is meant by "element" when talking about RPTV crt guns?

Discussion in 'Archived Threads 2001-2004' started by Richard Watt, Aug 30, 2001.

  1. Richard Watt

    Richard Watt Agent

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    I am doing some research for my first RPTV purchase and I have noticed that you can get 5-element guns and 6-element guns, etc. What does this mean? Is a 6-element that much better than a 5-element?
    BTW, I am looking at the Mitsubishi 55859 and the Toshiba 50HX81. I have seen the Toshiba up close two times and it looks awesome. Although the Mits doesn't look too shabby either.
    Just in case you wanted to know, Electronic's Express here in Nashville has the 50HX81 in stock and on display.
    Edit:
    Are there any ISF techs here in the Nashville area that you would feel good about configuring your tv?
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    27" Mistsubishi
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    [Edited last by Richard Watt on August 30, 2001 at 09:13 PM]
     
  2. JohnnyG

    JohnnyG Screenwriter

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    'Element' actually refers to the lens, not the CRT. Generally, the more elements in the lens, the better. The lens is a pretty critical component of an RPTV.
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    John Golitsis
    Next Big Thing Electronics
     
  3. Richard Watt

    Richard Watt Agent

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    Thanks for the reply. I realized the mistake I made after I went back to re-read my post.
    Is there any place online that offers a technical explanation of the lens element?
     
  4. JohnnyG

    JohnnyG Screenwriter

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    I have no idea, but you may want to search for camera lenses which might have the same concept??
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    John Golitsis
    Next Big Thing Electronics
     
  5. Michael St. Clair

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    I beg to differ.
    In general, the fewer elements in a lens, the better. Most people think of a lens as a piece of glass, but what is called a lens today is made of multiple pieces of glass. Just like the 50mm 'lens' you attach to your 35mm camera.
    All things remaining equal, when there are more elements in a lens, you get more internal reflections, less overall light transmission, lower contrast, and lower effective resolution.
    The fewer the better!
    Of course, in the real world, all things do not remain equal. On-axis versus off-axis performance is a consideration. Still, you keep the number of elements as low as possible while still meeting your overall design criteria!
    [Edited last by Michael St. Clair on September 01, 2001 at 10:42 PM]
     
  6. Allan Jayne

    Allan Jayne Cinematographer

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    Fewer elements means fewer reflections but generally the better picture will be had with the lens systems with more elements.
    Camera and TV makers would love to be able to make single element lens systems and save on cost, but unfortunately having just one element tends to give rainbow fringes (chromatic aberration), inability to focus both the center and edges at the same time (curvature of field), bowed lines (pincushion, barrel distortion), and a host of other problems.
    You will want to bring along your AVIA or Video Essentials and view one of the grid test patterns, check the grid lines along the picture edges for sharpness, freedom from rainbow fringes (also caused by misconvergence), also uniformity with the grid lines in the middle.
    Other video hints: http://members.aol.com/ajaynejr/video.htm
     

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