CurtPalme.com Home Theater Forum

[Rattanee]

So I'm looking at making a blend setup... however I have checked the available dimensions in my movie room and am not sure if I should...

Let's start with the screen. The wall I'm projecting on to has an available wall surface of 350cm wide, 210cm tall (yes low ceiling... It sucks). I'm going with multiple formats on this surface for certain (4:3 aspect for retro gaming, and something different for the blend...). That being said, I want to leave some space on the bottom and/or top to aid in visibility (to avoid a light fixture on the ceiling and/or a possible center speaker...). This would have the size nearly ideal for a 16:9 image at 337x190cm! Wohooo! Right? Well not really...

If I had a single high end PJ It would be ideal, but for a blend, well... here's the catch. I'd need to project 1:1 images with both PJs to get a usable blend zone. It would possibly still be a little wider then optimal, but shouldn't pose a real problem. However, I'm not sure about how this would work with regards to phosphor use? It would be ideal I think if I could maximize the raster on both projectors so that when eventual wear sets in and I want to reposition the PJs, I'd still have usable tubes. Or is it the case that because of projection angles, 1:1 on the tube face would be closer to filling out the 4-3 phosphor completely?

If I look at both PJs projecting 4:3 on the wall, the blend zone would have to be -huge-...

Another possibilty would be to use 4:3 and create scope. That would leave me more room for speaker placement, however I am not sure how that would be done to still be able to deal with the output from BD players... this latter is very hazy...

Could anyone who1s done a blend already give me some advice on the matter?

[gjaky]

A 337cm wide screen is a bit much for even hard driven 9" CRT, so a blend would make sense. However the blend is most usable with 2.4:1 aspect ratio, and not with 16:9, this is a lesser problem since most movies are already in 2.4:1.

[Rattanee]

Right now I have 287x200cm (a slightly squashed 4:3) from the PG9, in 1280x1024 It's driven at factory settings, and since the room is dark, I don't have a problem with brightness. (I hooked up the PS3 yesterday via the HDfury and to my surprise, 1080P went without a hitch! Quite a pleasant surprise to be honest! Since I still have to re-do CPC, I didn't even notice it being any more blurry then 1280x1024).

What has me confused/curious, is what a BDplayer will output. Say I grab a BD that is in scope. Will the player output 1080p with the 2.4:1 material scaled to fit into that resolution (letterboxed)? I'll need a separate scaler won't I? Also, if I have the PJs set up to 2.4:1, how would I deal with anything in 16:9 format? Just blank out the top and bottom? Not a fan of cutting off anything from a movie's picture...

[ecrabb]

A BD player outputs 1920x1080 w/square pixels, i.e. 16:9, irrespective of the source material. It's encoded letterboxed on the BD, so there is no scaling.

So, yes you need a scaler to "crop" the video vertically to output 2.40:1. Your output then is only 1920x800, which a blend processor can then split into two halves.

The two halves are something like 1056x800 each, with a 192-pixel overlap/blend zone. That's a more square resolution for each projector, so each projector uses much more of the tube face. Because the raster is expanded vertically, vertical resolution goes way up, and because you're only sending 1066 horizontal (and probably scanning at 48hz for movies, horizontal resolution goes way up.

So, you get better phosphor utilization, more brightness, better vertical resolution, better horizontal resolution, and the ability to run with a much larger scope screen (vs. a single projector). It's all perfect for movies, and it's all win-win, save for the part where you need two projectors, blend hardware, two processors for nailing down grayscale on both projectors, and the expense and hassle of setting it all up.



I may be off on the numbers a little, but that's the general idea. Athanasios (@Nashou66) could fill you in on all details.

SC

[ecrabb]

Oh, and with a scope screen, most people simply display 16:9 "pillarboxed" in the center of the scope screen with black sides, resolution and phosphor/screen utilization be damned. The setup is typically referred to as "constant image height" or CIH, meaning no matter the aspect ratio, the image will aways be the same height.

SC

[Rattanee]

Thanks, that explains a lot... I've been measuring things too, and I hate my low ceiling... If I do the blend, the projectors will be in front of the seating... I wouldn't mind that if I had more height to hide the beasts somehow... I could possibly actually get away with three projectors all pointing perfectly straight, so no asymmetrical trapezoid wear on the CRT faces either...

I even thought about having longer unistrut 'rails' installed so I could move them back and forward to switch between stack and blend... I could even make rotating mounts for repeatable positioning, but optical focus would need to be set every single time so I guess there is no real point...

So the big question now is whether I want to do a stack setup, or a blend...

The blend would probably give me better focus, but be in scope format, and costs a bunch more... plus I'd see the back of the blend PJs from my seating...

The stack would give me worse focus due to bigger spot size on the wall, but I could get away with a full size 16-9 aspect ratio, technically filling most all of my available screen space...

I am at an impasse... no idea which to go with....

[AnalogRocks]

Buy more projectors, do a stack + a blend and use two screens

[AnalogRocks]

Buy more projectors, do a stack + a blend and use two screens

[Nashou66]

From a blender who is 100% honest. Do a stack, less head aches. I had both and didn't mind the slight loss in resolution from the stack which also gives more light output over a blend.

Nashou