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post #1 of 15 Old 01-25-2020, 12:42 PM - Thread Starter
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Help me understand something.

With an anamorphic lens, a scaler is required to compress the image in order for the lens to work.

A native panel of 16:9 needs 1.33 to expand to scope.

But if we're using a different ratio anamorphic lens, say a 2x lens... then the image needs to be compressed by 2.

My question is... is there any way to use a lens with a compression factor different than 1.33x WITHOUT wasting part of the native panel?
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post #2 of 15 Old 01-25-2020, 12:44 PM - Thread Starter
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My ideal screen ratio is 2:1.

But I can't project this without losing the top and bottom of the native panel.

And I've tried to use my brain on this, but it's essentially given up because I'm half-convinced that it isn't possible.

What lens could I use to compress the native panel's output into a 2:1 ratio?
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post #3 of 15 Old 01-25-2020, 01:26 PM - Thread Starter
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Would something like the Prismasonic Cinomorph be able to do it? I understand you can adjust the prisms with this?
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post #4 of 15 Old 01-25-2020, 03:31 PM
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What is your source? An HTPC? otherwise you will need an outboard scaler which means big bucks, along with a lens. There really isn't any good reason to do what you are asking. And the lens ratio you will need to be looking for is 1.12, not 2.0. You multiply the lens ratio by the native ratio to get the projected ratio. 1.78 x 2.0 would give you a 3.16:1 screen.

Prismasonic did make variable lenses, but I think their current line replaced the variable feature with a focusing capability, so you'd need to look at an older one. They were continuously variable from 1.0 to 1.33.

Is your plan to scale everything to exactly 2.0? So you will be cropping content down?

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post #5 of 15 Old 01-25-2020, 08:13 PM - Thread Starter
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Originally Posted by ScottAvery View Post
Is your plan to scale everything to exactly 2.0? So you will be cropping content down?

Yeah after I made the thread, I ran the math to determine that there were no current lenses that would work with the math. That's why I asked about the Prismasonic.

It may not be possible, or ideal... but I enjoy having a larger area in which to fit films. Maybe I am just too used to 16:9 material being taller than scoped stuff, I don't know...

Part of the issue is that if I do a scope screen at the height I prefer 16:9 content, I'm pushing the limits of my room. I have a VC lens, but it obviously doesn't work ideally with my setup (throw ratio at the extreme). I know a HE lens will work, and I can get a UH480 for around $400.

I guess I just like the 2:1 screen size? I watch a lot of 4:3 old movies, and I really don't want them to be smaller than they already are.

I mean... I could easily do a CIH 2.35 screen without the lens... the only reason I still think about lenses is that I would ideally be using the full panel/light output.
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post #6 of 15 Old 01-25-2020, 08:17 PM - Thread Starter
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Oh, and yeah, my source is an HTPC. The desktop is a custom 2:1 resolution, and the top and bottom of the panel are masked.

Essentially, this just reduces the amount of black bars on scoped content while allowing other formats to appear larger than they otherwise would.
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post #7 of 15 Old 01-26-2020, 06:50 AM
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Quote:
Originally Posted by Dennis Moore View Post
Yeah after I made the thread, I ran the math to determine that there were no current lenses that would work with the math. That's why I asked about the Prismasonic.

It may not be possible, or ideal... but I enjoy having a larger area in which to fit films. Maybe I am just too used to 16:9 material being taller than scoped stuff, I don't know...

Part of the issue is that if I do a scope screen at the height I prefer 16:9 content, I'm pushing the limits of my room. I have a VC lens, but it obviously doesn't work ideally with my setup (throw ratio at the extreme). I know a HE lens will work, and I can get a UH480 for around $400.

I guess I just like the 2:1 screen size? I watch a lot of 4:3 old movies, and I really don't want them to be smaller than they already are.

I mean... I could easily do a CIH 2.35 screen without the lens... the only reason I still think about lenses is that I would ideally be using the full panel/light output.
There is nothing wrong or no reason you can’t do a combination of using an A-lens and employing some software external or in the projector to take care of giving you a brighter and higher pixel image for scope and still using zoom to fill your 2.00:1 screen the other direction. One method does not exclude the other if you have a method to slide the lens out of the way and enough capabilities left in the zoom of the projector. I have never ran an expansion lens though and always have preferred changing my image size with just some method of zoom, focus and shift.

If your room is not wide enough as you say moving your seating a little closer will make your room virtually wider in terms of immersion. Chances are if you are like me you still may find your Academy movies a little under immersive though.

Bud

Last edited by bud16415; 01-26-2020 at 11:30 AM.
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post #8 of 15 Old 01-26-2020, 08:29 AM
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Going back to your original question, yes, you can use other ratio lenses with appropriate scaling (more than just setting the desktop). The thing is, you will either be throwing away pixels of the panel OR pixels of the source material for anything that is not natively 2.0 (Premium streaming). There are more than 10 actively used Aspect Ratios in current content production, so even a projector with lens memory can't catch them all. You just have to decide which ARs are important to you and plan from there.

I do as Bud suggests, and move the lens out of the way. Anything 2.35 or above uses the lens, and anything below doesn't. lens memory handles the in-betweens, and I do lose some pixels on those, but the majority of content is pretty close to either 16:9 or 21:9, so very little is lost - a little overshoot into masking. 1.33 ratio lenses works for most cases and is the only commonly supported ratio. 1.25 is only supported in high end Sony/JVC pjs, and anything else requires custom scaling with a Lumagen or other external solution.

I can see now why you would want your minimum ratio to be 2.0 and use all the panel, but doing so really does beg for a VC lens and I am not sure if any of those are variable.
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post #9 of 15 Old 01-26-2020, 11:27 AM - Thread Starter
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Yeah, I don't want to fiddle with moving a lens on or off. The way it currently works is great... I'd just rather have all the available light and resolution.
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post #10 of 15 Old 01-29-2020, 11:57 AM
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Quote:
Originally Posted by Dennis Moore View Post
Yeah after I made the thread, I ran the math to determine that there were no current lenses that would work with the math. That's why I asked about the Prismasonic.

It may not be possible, or ideal... but I enjoy having a larger area in which to fit films. Maybe I am just too used to 16:9 material being taller than scoped stuff, I don't know...

Part of the issue is that if I do a scope screen at the height I prefer 16:9 content, I'm pushing the limits of my room. I have a VC lens, but it obviously doesn't work ideally with my setup (throw ratio at the extreme). I know a HE lens will work, and I can get a UH480 for around $400.

I guess I just like the 2:1 screen size? I watch a lot of 4:3 old movies, and I really don't want them to be smaller than they already are.

I mean... I could easily do a CIH 2.35 screen without the lens... the only reason I still think about lenses is that I would ideally be using the full panel/light output.
Two screens - a wider scope screen, and a taller 16:9 screen is what I use, for the same reason you mentioned.
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post #11 of 15 Old 01-30-2020, 10:42 AM - Thread Starter
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Two screens - a wider scope screen, and a taller 16:9 screen is what I use, for the same reason you mentioned.
I have definitely seen your setup before... very nice.

The room just doesn't allow for it, unfortunately. The ceilings are 10' and the screen hangs from the ceiling above a fireplace that is not used... there is a mantle about a foot deep behind it, maybe 4.5' tall.

Maybe if I get a new projector some day, the zoom method would work better. My RS45 tends to lose a small amount of focus each time it auto zooms to a different setting, and the shift is always slightly off. So leaving it in a constant state is ideal.
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post #12 of 15 Old 01-30-2020, 12:52 PM
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I have definitely seen your setup before... very nice.

The room just doesn't allow for it, unfortunately. The ceilings are 10' and the screen hangs from the ceiling above a fireplace that is not used... there is a mantle about a foot deep behind it, maybe 4.5' tall.

Maybe if I get a new projector some day, the zoom method would work better. My RS45 tends to lose a small amount of focus each time it auto zooms to a different setting, and the shift is always slightly off. So leaving it in a constant state is ideal.
I haven't found the focus or less shift to drift on either the RS600 I had or the current projector. But if the room doesn't allow for it, and you don't want to make modifications, not much you can do.
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post #13 of 15 Old 01-30-2020, 01:08 PM - Thread Starter
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I haven't found the focus or less shift to drift on either the RS600 I had or the current projector. But if the room doesn't allow for it, and you don't want to make modifications, not much you can do.
Confirmed via Prismasonic that their prism lenses will do the required stretch factor for a 2:1 screen ratio.

Now I just have to try to find a used one for a reasonable price... not so easy.

Almost makes me want to try playing around with different DIY prisms, but I figure that would be a waste of time.
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post #14 of 15 Old 01-31-2020, 12:17 AM
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Originally Posted by Dennis Moore View Post
Confirmed via Prismasonic that their prism lenses will do the required stretch factor for a 2:1 screen ratio.

Now I just have to try to find a used one for a reasonable price... not so easy.

Almost makes me want to try playing around with different DIY prisms, but I figure that would be a waste of time.
AVScience sold a rebranded Prismasonic years ago, so keep that on your search list. I've seen that model offered on the classified section here.
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post #15 of 15 Old 01-31-2020, 09:29 AM
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Originally Posted by Dennis Moore View Post
Confirmed via Prismasonic that their prism lenses will do the required stretch factor for a 2:1 screen ratio.



Now I just have to try to find a used one for a reasonable price... not so easy.



Almost makes me want to try playing around with different DIY prisms, but I figure that would be a waste of time.


I did a DIY solution years back but the quality just wasn’t there. You’ll get a lot of chromatic aberration, and reflections all over the room unless you find prisms with optical coating.

It was a fun project but it only whet my appetite.
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