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Discussion Starter · #1 ·
Found this on the Home Theater Magazine site. Anyone know about it or personal experience? Was considering to keep the nephews/nieces off my home theater when they are over. I have any extra 19" TV I could use and a bare finished basement wall.

http://www.gobigtv.com/


Thanks

Dave
 

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that's funny....i just had a dream about something like that last night. never heard of it before. it sounds like a "good" idea in theory, but i seriously doubt it works as well as advertised. apparently all it's doing is magnifying the crappy picture from your $80 13" tube tv to an enormous size. that's just going to magnify the imperfections beyond reasonable levels.


i dunno though, for only $20 or so, i'm sure it would please any kids trying to play video games or watch cartoons.
 

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Sam Runco used to build these as sets and sell them, back in the day. I did once also.


Problem is, whenever you dilute the light level by magnification, you lose tons of light level. Happens on 10x optical zoom lenses on still cameras, whether digital or not - you lose proportional amounts of light whenever you magnify ANYTHING.


CRTs in RPTVs are driven very hard, to come up with the light levels you see on your rear projected screen. There are 3 of them. The fresnel/lenticular combination of rear pj lenses forcusses the light path straight out at you, gathering light levels even more for you.


The exact same complement of 3 CRTs projected on a screen in a FPTV situation has far less light emanating potential than RPTVs have because they have no fresnel/lenticular combo. For those, you can't even see them during the daytime hours like you can RPTVs. You need complete light isolation and/or nighttime viewing to be able to fully enjoy FPTV.


Now factor in that you are using the light level of a 13" or 15" CRT DV TV, magnified to 150". Could it be any more laughable? Even FPTV enthusiasts with 3 gun $30K pjs don't like having bigger than 96" screens because the light levels suffer so much from the light scatter inherent in FPTV applications. And this is with relatively high gain, respectfully reflective screens by Stewart and Da-Lite. Think how much less light would actually be reflected from a simple wall.


If the screenshot examples used in the pix given in the link are actually for real - which I doubt - they had to time-expose them as freezeframes interminably to be able to gather enough light level to actually use and photograph.


The pic on my website, from my 65" Panny, required the shutter on my Canon Photura 35mm analog camera to stay open several seconds, even tho it is an RPTV, with the great fresnel/lenticular combo. On a pj'd 15", the time it would have had to stay open would have far exceeded my camera's time exposure capabilities.


Add to that the fact that RPTVs use lenses that contain 4 individual lenses each, in each lens pack. The fresnel lens mentioned in the link is one lens. No refraction correction at all, which means the r, g and b images would separate greatly at the edges, just like they did in the initial offering DLP RPTV units.


I repeat my comments above, about the laughability of this type of pj system, compared to today's technology.


However, it may work for the application you have in mind - the kids... assuming it would keep their attention, with its ultry low light levels...



Mr Bob
 

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Discussion Starter · #4 ·
Thanks guys. I see what you mean. My only objective with this would be for kids visiting on video games, in a finished basement with no windows.

Maybe I'll wait and see if it sticks around bit first. If I get some free time to build the box maybe I'll do it. Hey for $20.00 who really cares. Then again $20.00, if enough people spend $20.00 someone can get rich quick.
 
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