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Discussion Starter · #1 ·
If you could do either rear or front projection, which would you do and why?


My next house will have a storage area next to the HT room and I am considering setting it up for rear projection. I will be using a digital projector (probably D-ILA) and want a large screen (100-120" wide). Any thoughts much appreciated.
 

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Also, rear projection the picture is shot right at you rather than reflecting off the screen for front projection. To me, the picture seems better when using the projector as a rear projection unit.
 

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rear projection all the way...


man, i SOOO wish i had the space to do that, i'm even thinking of tearing a wall down to do it =P, seriously, there's no contest if you got the room.

the birghtness of those extremley expensive screens like silverstar and grayhawk would be put to shame by a properly done RP screen, you could watch it with the lights on, no one would interfere with the sight of the projector, less noise, better looking (no PJ hanging on the roof or wall), and the "high gain" screen materials of the silverstar would be matched easily, and i'm willing to bet exceeded.


let us know how it turns out, and post some screenshots of your setup =D.
 

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Rear Projection if I had the space and could find an artifact free RP screen (they probably exist, but I haven't researched what is available).
 

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Let me add to the unanimous vote. Rear projection, most definitely!
 

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RP, that's what I'm going to do, too.


Although if I could, I might opt for an RPTV for day and FP for night; I can't control light even at night. And that way you preserve the specialness and "wow that's big" effect for movies; no matter how big a screen you have, if you watch it every day you get used to it.
 

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Discussion Starter · #9 ·
Ok, thanks. RP is looking good so far. I'm getting pumped!


I looked at the DaLite screens and hopefully I would not need one of those pricy fresnel lenticular screens. Not just because the price is prohibative, but because I thought the fresnel screens in RPTVs make a picture inherently inferior to that of a front projection setup.


So, if I get something like the JVC DLAHX-1U with 1000 rated lumens and a 108" wide 16:9 screen, I should be fine with a unity gain diffusion screen. That should give me about 23 FL. Am I missing anything? Would I have enough brightness to go a to a little larger screen or should I go to a grey screen? The room will have pretty good light control but may be used with some lights on for sports or other events.
 

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Quote:
I may be doing RP - anyone 'in the know' with RP screens?
I'm not really 'in the know', but Dazian makes some low cost rear projection screen material for about $20 a yard. I think they said it comes in 84" widths. They will send you a sample at your request.
 

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Quote:
Originally posted by Songer
....hopefully I would not need one of those pricy fresnel lenticular screens. Not just because the price is prohibative, but because I thought the fresnel screens in RPTVs make a picture inherently inferior to that of a front projection setup.
You're kidding right?


So, people and corporations spend thousands more than they have to in order to obtain an 'inherently inferior' image?


Do you know what the functions are of the fresnel lens, or a lenticulated surface? Or, even why they're there?


There are several links in posts from this forum that point to sites explaining these functions. Stewartfilm.com is one, but others go into more depth.

http://www.stewartfilm.com/engineeri.../optawave.html


- Chris
 

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rear definately. in fact ever since i've gotten my X1 i've been thinking about how to make it a RP, including building a cabinet and making essentially a RP TV (the throw is just too long for that though).
 

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I've posted quite a bit about RP, to the point where I just can't stand top repeat it again. If you can get the search to work there are several threads with links to various informative sites.
 

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Discussion Starter · #14 ·
Quote:
quote:quote:

--------------------------------------------------------------------------------

Originally posted by Songer

....hopefully I would not need one of those pricy fresnel lenticular screens. Not just because the price is prohibative, but because I thought the fresnel screens in RPTVs make a picture inherently inferior to that of a front projection setup.

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You're kidding right?


So, people and corporations spend thousands more than they have to in order to obtain an 'inherently inferior' image?


Chris


Fresnel / lenticular screens are basically engineered to maximize light output with short throw projectors, right? Some have commented that the limited pitch of the lens structure can cause artifacts or worsen the picture. The effect is presumably minimal and worth the gain in light output for a RPTV.


If I have adequate light output and dispersion without the Fresnel/lenticular lens, what else would I gain over a regular coated screen? Or are you saying that RPTVs can generate as good a picture as front projectors?
 

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Songer -


Not all fresnel screens are for short-throw lenses. The pitch of the grooves can be specified for different distances.


So, it's similar to installing the wrong size tires on a car in that it will typically throw off the handling and maybe performance too. Many, if not most LF screens have a pitch designed to be set up with short-throw lenses. Some have gotten a hold of such a screen and after throwing their standard pj lenses against it.....were disappointed, as they should have been.


I'm familiar with the Barco Reto's 67" LF rear screen which does have a short-throw pitch. But, we have a Stewart Opta 90" that was used with a NEC 6PG's standard lens.....and a large mirror (which Noah has now). Our eventual plans are to use this screen with a Barco Graphics 801s.


Noah has indeed posted a great deal on the subject of RP screens and his posts are worth searching for and reading if you're new to this. BTW, I use the search almost every day and have not had any problems with it. However, much of this material needs to be searched in the archives.


I agree though, that if you're going to employ a powerful PJ you won't benefit as much as a CRT almost needs to from the enhanced gain that a fresnel lens offers.


My recommendation for the PJ you're using, and the large screen size you're going for......I'd grab a large sheet of plexiglass and coat it with RP screengoo. Supposed to be a very good image.....and not terribly expensive.


Oh, and though my vote is also for rear projection.....we have both; a Barco Data FP on to a 96" wide screen, and a Barco Retrographics 801s (each in different rooms). Soon it'll be just the 72" wide RP.


- Chris
 

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ChrisH,


"and a large mirror (which Noah has now). "


Did you used to be Christopher Calder, or is my memory even worse than I feared?


Anyway, Fresnels are most needed for short throw to straighten out the steep ray angles befrore going through the diffusive material (which is what allows a viewable image to be frormed at the screen plane). They're generally not needed for throw ratios > 1.5:1.


The .5 mm or so pitch of the Fresnel ridges or lenticulations isn't a factor for a large aftermarket screen, since a pixel is about 4 pitches for a 100" wide screen.


For less much less cost and trouble than a big sheet of Plexiglas and Goo you can buy flexible rear screen material.
 

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Discussion Starter · #17 ·
K, thanks. I tried a search but didn't see the archives.


And Noah, you have 1700+ posts in the past year and a half. I have my work cut out for me.


My room behind the HT room is only 10 - 11' deep, so it sounds like I will either need a FL screen with a short throw projector or a mirror system. I'm not sure I can fit that in my budget. The search continues...



-Steve
 
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