What to look for in a projector for Poor Man's Zoom Trick? - AVS Forum
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post #1 of 14 Old 03-20-2010, 10:47 AM - Thread Starter
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I'm thinking of upgrading my projector. Right now, I have an Optoma HD7100. It's a decent enough 720p projector with good optics. The key factor with my current projector, is that it is DLP with vertical and horizontal lens shift. I'm partial to DLP, and to do the PMZT (Poor Man's Zoom Trick), I obviously needed one with vertical lens shift.

Now, I want to move up to 1080p, but I'm wondering if there are any other factors that I "need" to strongly consider if I'm going to be using it for PMZT (along with watching regular 16:9 stuff). Here is what I think I need:


1. Vertical Lens Shift - I'm guessing that this is probably the most crucial aspect. When you zoom out the picture, it drops way down, so Vertcial Lens Shift is an absolute must so you can raise your picture

2. Zoom of 1.33 or greater - My current projector actually has a 1.25 zoom. This isn't ideal for PMZT because in my current situation, the 16:9 area of my screen is about 5 inches longer (vertically), than the overall 2:35:1 area of my screen. The way I understand it (although I might be completely off base), is that if you have a zoom of 1.33 or more, then the screen would have a uniform length (top to bottom). This means I would no longer need to mask a 9 foot by 5 inch bottom area of my 16:9 screen when I'm watching 2:35:1 material.

3. Horizontal Lens Shift - When I zoom out my picture for 2:35:1, the picture drops down dramatically. Then I need to use the Vertical Lens Shift to raise the picture. However, when using Vertical Lens Shift, it seems to also shift the image slightly horizontally, and thus, having Horizontal Lens Shift is a nice thing, because then I can use the horizontal lens shift and get my screen lined up perfectly. Now, I'm thinking that if I somehow found a projector with only vertical lens shift, I would be able to live with it (if I had to), because I could just swing the projector slightly to the left or right to compensate. I'm thinking this would reduce my picture quality slightly, but it might not be that noticeable. Still, it would be ideal to get both vertical and horizontal shift it possible.

Other than these 3 factors, is there anything else I should be looking out for?
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post #2 of 14 Old 03-20-2010, 11:20 AM
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Quote:
Originally Posted by Anthony1 View Post

I'm thinking of upgrading my projector. Right now, I have an Optoma HD7100. It's a decent enough 720p projector with good optics. The key factor with my current projector, is that it is DLP with vertical and horizontal lens shift. I'm partial to DLP, and to do the PMZT (Poor Man's Zoom Trick), I obviously needed one with vertical lens shift.

Now, I want to move up to 1080p, but I'm wondering if there are any other factors that I "need" to strongly consider if I'm going to be using it for PMZT (along with watching regular 16:9 stuff). Here is what I think I need:


1. Vertical Lens Shift - I'm guessing that this is probably the most crucial aspect. When you zoom out the picture, it drops way down, so Vertcial Lens Shift is an absolute must so you can raise your picture

2. Zoom of 1.33 or greater - My current projector actually has a 1.25 zoom. This isn't ideal for PMZT because in my current situation, the 16:9 area of my screen is about 5 inches longer (vertically), than the overall 2:35:1 area of my screen. The way I understand it (although I might be completely off base), is that if you have a zoom of 1.33 or more, then the screen would have a uniform length (top to bottom). This means I would no longer need to mask a 9 foot by 5 inch bottom area of my 16:9 screen when I'm watching 2:35:1 material.

3. Horizontal Lens Shift - When I zoom out my picture for 2:35:1, the picture drops down dramatically. Then I need to use the Vertical Lens Shift to raise the picture. However, when using Vertical Lens Shift, it seems to also shift the image slightly horizontally, and thus, having Horizontal Lens Shift is a nice thing, because then I can use the horizontal lens shift and get my screen lined up perfectly. Now, I'm thinking that if I somehow found a projector with only vertical lens shift, I would be able to live with it (if I had to), because I could just swing the projector slightly to the left or right to compensate. I'm thinking this would reduce my picture quality slightly, but it might not be that noticeable. Still, it would be ideal to get both vertical and horizontal shift it possible.

Other than these 3 factors, is there anything else I should be looking out for?

(1) and (2) are required to zoom, but I'm not sure about (3). Horizontal and vertical lens shift should be independent of each other; changing the vertical lens shift doesn't change the horizontal alignment (if it does, there's a mechanical problem with the shift mechanism). At any rate, pretty much all of the projectors that satisfy (1) and (2) will also satisfy (3), so it's a moot point.

Nothing else is needed (projector wise) in order to do zoom CIH.
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post #3 of 14 Old 03-20-2010, 06:00 PM
 
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What is your budget?
i have a couple suggestions based on budget.

Scott
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post #4 of 14 Old 03-21-2010, 01:14 AM - Thread Starter
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Does anybody remember those Sony Wega TV's that had that resolution squeeze thing? They were 4:3 TV's from the early 2000's that would squeeze the entire horizontal resolution of the TV into the 16:9 area when watching 16:9 material on it. So no wasted resolution would be spent on the black bar area. Can any Projectors do this? What I mean is, if they are 16:9 projectors, could they squeeze all that resolution into just the 2:35:1 area if you select something in the menu?

If that would work, then that would benefit people using PMZT... right?
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post #5 of 14 Old 03-21-2010, 03:40 AM
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My very first projector (a Sanyo LCD) had this V-compression you mention. It seems that because 16:9 projectors are already 16:9, there is no need for this. And given that you are aware of this feature, you would also know that when not using the VC mode that the 16:9 image always looked vertically stretched.

I know I always get hammered for this, but I will say it again any way. In most cases, the mode that provides the scaling for VS is actually just a 4 x 3 mode. The reason it removes the black bars on Scope program is that there is simply not enough vertical pixels to show the bars. If the 1920 panel was 4 x 3, it would have 1440 vertical pixels, not 1080.

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post #6 of 14 Old 03-21-2010, 03:58 AM
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Quote:
Originally Posted by scottyb View Post

What is your budget?
i have a couple suggestions based on budget.

Scott

Hi Scott,

I have a similar question. I need an interim projector, until next year (when my budget increases again). I have a 120" Screen Research AT screen with 0.95 gain. The room is 100% light controlled and completely back (bat cave).

Budget is US$1800 and would like 1080p. I have an ISCOIII lens with sled, but guessing with this budget, I will need to zoom to start?

1. Do I need to zoom or is there a cheap projector with stretch as part of it's software?

2. Any suggestions, based on price.

This will be an interim until around CEDIA 2011.

Cheers,

Chris
PS. I could live with 2nd hand, if it helps.
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post #7 of 14 Old 03-21-2010, 04:10 AM
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Originally Posted by Chris1971 View Post

I could live with 2nd hand, if it helps.

What happened to your last projector? If it is just a TEMP, why not just grab a 2nd BenQ W5000 or similar? They sell locally for the price you have listed.

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post #8 of 14 Old 03-21-2010, 04:22 AM
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Originally Posted by CAVX View Post

What happened to your last projector? If it is just a TEMP, why not just grab a 2nd BenQ W5000 or similar? They sell locally for the price you have listed.

Hi Mark,

Long time. Never ended up getting that last projector. Cinema is only now being built (you can check it out here: http://www.avsforum.com/avs-vb/showt...33326&posted=1). This will be an interim until next yr, when my bonus comes through again.

Drop me a line, let me know how you're travelling... chris_at_neary_dot_com_au

Cheers,

Chris
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post #9 of 14 Old 03-21-2010, 04:36 AM
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Will do

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post #10 of 14 Old 03-23-2010, 10:26 AM - Thread Starter
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Why isn't there some type of technology that would allow the projector to not project the black bar area of the image? What I mean is, when doing the PMZT, the projector is still projecting the black bars onto the screen, and even if you have a very black background surrounding your screen, it's still putting out extra light that you'd rather not have bouncing around the screen area.

If the projector had an internal mechanism that would allow it to only project the 2:35:1 part of the image, basically the all of the image that isn't the black bars, then it would help us Poor Man Zoom guys. We could just zoom out the 2:35:1 portion and not have the extra light spilling into the room from the projected black bars.

This, and some type of vertical resolution squeeze would be an awesome thing.
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post #11 of 14 Old 03-23-2010, 03:13 PM
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Quote:
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This, and some type of vertical resolution squeeze would be an awesome thing.

The only time electronic VC would be required is if BDs went true anamorphic. Right now they are 1:1 mapped inside the 1920 x 1080 frame.

Applying an internal shutter could work if it was between the imaging chip and the lens. Native 2560 x 1080 projectors would be better.

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post #12 of 14 Old 04-05-2010, 08:07 AM
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I'd still like to see the OP's ? answered.

CAVX, I remember reading in your blog you reccomend a lens w/ a 1.5x zoom capibility. Why is that?

As the OP said, if 1.33x is what an AM lens would stretch, then wouldn't you just need a 1.33x zoom to match that?
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post #13 of 14 Old 04-05-2010, 10:48 AM
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Originally Posted by biliam1982 View Post

CAVX, I remember reading in your blog you reccomend a lens w/ a 1.5x zoom capibility. Why is that?

As the OP said, if 1.33x is what an AM lens would stretch, then wouldn't you just need a 1.33x zoom to match that?

1.33x zoom is the absolute minimum for zoom CIH; there would be exactly one correct projector mounting position for a given screen height.

If the projector has 1.5x zoom, that would allow some flexibility in the projector location (throw ratio).
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post #14 of 14 Old 04-06-2010, 04:43 AM
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Quote:
Originally Posted by biliam1982 View Post

I'd still like to see the OP's ? answered.

CAVX, I remember reading in your blog you reccomend a lens w/ a 1.5x zoom capibility. Why is that?

Quote:
Originally Posted by ilsiu View Post

1.33x zoom is the absolute minimum for zoom CIH; there would be exactly one correct projector mounting position for a given screen height.

If the projector has 1.5x zoom, that would allow some flexibility in the projector location (throw ratio).

Ilsiu is right on. When I did zoom (prior to going to a lens back in 2005), my projector offered approx 1.3x zoom, so was always just a tad short for the zoom method. At the time I had a rail type track mount that allowed me to drag the projector back slightly to make up the small amount. With no vertical shift, the alignment was a PITA.

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