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Discussion Starter · #1 ·
Am I correct in understanding that creating a constant height setup is as "simple" as this:

-Using a 16:9 projector with power zoom & focus on a 2.35:1 screen

-Using side masking to create 1.33, 1.78 & 1.85 viewing areas

-Using one zoom setting for 1.33 & 1.78 (16:9)

-Zooming to bring 1.85 & 2.35 to the proper height?


This is my first post and I'm happy to be here and interested in learning more. Let me know if my question isn't clear enough. Thanks.


Josh
 

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If the projector has no offset and a suitable zoom range its possible...


A lot of projectors have an offset so that any zooming also repositions the image...


Of course a 16:9 machine with a panamorph is a possibility depending on scaling issues etc.
 

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Discussion Starter · #3 ·
Thanks for the response.


In other words, does this mean that you would have to use a projector with no offset (or adjustable) with the centerline of the lens lined up with the centerline of the screen?


Does that mean a setup like this would cause the image to move when zoomed:

Sanyo PLV-70 ceiling mounted with the image below the line of the lens?


Thanks for the info.


Josh
 

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I have checked the numbers on a couple of 16:9 projectors (HS10 and Z1) and neither of them have enough zoom range to accomplish what you are talking about without having to physically reposition the projector. There is usually about a 1-foot distance gap is the necessary throw distances.


RG
 

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I do something close to this with my Sony 10HT and a panamorph.


You will have to have better than 1.33 zoom - my projector has only 1.2 which is not enough to get exactly constant height.


Another point, even if you have a proj that has 1.33 or better, you really don't want to be at the max zoom as the optics usually won't be as good.
 

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personally, I think the iscoII is a better fit for a constant height setup. This lens really does not introduce a big change in the vertical location of the image - just makes it 33% wider (and increases image height about 5% or so).


I am definitely going to hook up a sliding mechanism when I get a 16*9 pj.


btw, I use the projectors zoom to keep area (almost) constant when going from 1.78 to 1.85 to 2.35. I think constant area is a decent compromise to constant height when you are not using full panel resolution.

-jeff
 

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Josh,

Do a search on constant height and you will find many enthusiastic proponents.


It can be very simple.


You don't need power zoom and focus. It's convenient, but if you can reach your projector, you can do it manually. It's only once per movie.


You also can often get away without any sort of sliding mechanism. I use a fixed height screen with a 10HT on a fixed mount. The specs say the zoom ratio is only 1:1.15, but really it's a bit larger. Using the method you mentioned (zooming the image) I can either have a scope movie with 1/2 inch of letterbox , or a 16:9 image which overshoots the screen a bit (1/2 inch on the top and bottom). I choose the latter, and although not perfect, with good masking, it sure beats dealing with some sliding mechanism. Of course if you get a projector with a zoom range greater than 1:1.33, you won't have to worry about it at all.


You will have to worry about repositioning the image. If you have lens shift, you can use that. If not, most projectors can shift the image up and down electronically, allowing you to position the letterbox image anywhere within the 16:9 frame thrown by the projector. Your scope screen will need extra masking either above, below, or both, because when zoomed in, your 16:9 frame will be taller than your viewable area. No matter how good your blacks are, you want that overshoot to fall on masking.


Get your projector first, and try it all out on a wall or something, then you can order your screen with the correct viewable area and masking.


An added benefit of constant height is that you need only vertical masking (like curtains) to frame all film shapes.


You can make it as complicated as you like, but you can also keep it very simple.


Good luck,

Pip
 

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Discussion Starter · #8 ·
Thanks for all the info, everyone! I've been reading this forum for several years and really appreciate your responses to my first post.


Does anyone have experience or thoughts on accessory lenses, either telephoto or wide? Again, using the Sanyo PLV-70 as an example, their distance calculator shows that the optional lenses can create the proper screen sizes within the zoom range. Do these adversely effect image quality? Thanks.


Josh
 

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The "best" way to do a constant height setup is to use an anamorphic lens combined with digital scaling, as Phat Phreddy alluded to.


If you need a longer throw, use the panamorph... if you need a shorter throw, use the ISCOII. I don't think there are any significant differences between the end result except how they affect projector placement (note that the panamorph also requires the pj to be mounted higher... a good thing for some people with tall ceilings, bad for those with low ceilings).


Combine the anamorphic lens with either a stand alone digital scaler or an HTPC. The scaling stretches a 2.35:1 image vertically to fill a 16:9 pj (this can also apply to 16:9 stretched to 4:3), and then the anamorphic lens stretches (or compresses, as the case may be) the image back to 2.35:1. Doing this gives you the full resolution of the pj, and requires no zooming, manual or otherwise.


All you then need is horizontal masking for 16:9, 4:3...
 

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Josh,

If your sold on the PLV-70, and you're willing to zoom, the standard lens might have enough zoom range to do the job. Eg: with a 92" wide scope screen, your viewable area height will be 41". When you're zoomed in for scope films, your projector's panel will be 52" tall. Check the throw calculator. If the distances for your two heights overlap, it will work.

Pip
 

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Rick,


I have a HS10 and fixed height setup, and there's plenty of zoom range. I've done it with both a 8' wide and (currently) 10' wide screen. I had to do some creative engineering for the lens shift, but it was well worth it, IMO.
 
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