Cylindrical A-Lens Owner's Thread - Page 21 - AVS | Home Theater Discussions And Reviews
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post #601 of 630 Old 04-01-2012, 03:12 AM
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Quote:
Originally Posted by coolrda View Post

Just had to snag this pic posted by fellow videophile W.Mayer of his dual Barco/Isco 1.25 4K3D projection system. He could quite possibly have the finest projection system in the world. A true spectacle.


That is very impressive indeed.

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post #602 of 630 Old 04-03-2012, 10:48 AM
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Quote:
Originally Posted by coolrda View Post

Hi Mark. So had I but he discusses in detail on another couple threads about the $15k Isco cinemaDLP 1.25 A Lens and the superiority of it when he compares it to the Isco III. From bouncing around and reading his posts it sounds like his complaint with the distortion which he demonstrates is what we call pincushion. If I understand him right he says the 1.25 doesnt have pincushion and focus is prefect at the extreme edges as well. Is this a fully geometrically corrected lens? Getgray can comment here but he stated both have the identicle glass. Maybe Mayer is seeing the distortion because his new projector's need the 1.25x lens due to the 1.896 AR. Remember these are 17:9 projectors unless run at 2160x3840.

There is nothing magic about the 1.25. I stand by what I said in the other thread, although I decided it wasn't good use of my time arguing there. The 1.25 will have the same geometry issues inherent with a 2 doublet A lens. I believe part of the reason he was seeing light drop off was he was vignetting and didn't know it. If the ray pencils are partially obscured at the lens it does not result in an image shadow on screen, but a light drop off as he described. As the 1.25 has less expansion, it will have less artifacts from expansion by definition. But those should be trivial and for the most part unmeasurable. Problem with that Sony and a IIIL is it has a fat beam at the physical exit point of the chassis. Someone that knows how to ensure no vignetting needs to check where it will, and will not fit.
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post #603 of 630 Old 04-03-2012, 03:10 PM
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Quote:
Originally Posted by GetGray View Post

As the 1.25 has less expansion, it will have less artifacts from expansion by definition.

And that alone is the only thing is has to offer IMO. $15K?

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post #604 of 630 Old 04-03-2012, 06:57 PM
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Originally Posted by CAVX View Post

And that alone is the only thing is has to offer IMO. $15K?

To be fair, it is substantially larger, so vignetting will be less of an issue and you could use it at shorter TRs. Of course it doesn't really cost that much, depending on where it comes from.
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post #605 of 630 Old 04-03-2012, 10:45 PM
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Can I assume there is an additional row to this theater? It would be a shame to put that kind of money into it and sit against the rear wall, where are the rear/side speakers?

-Sean
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post #606 of 630 Old 04-04-2012, 02:02 AM
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The other thing to consider too is that the ISCO III being 1.33x, was designed to work with HT projection where the ISCO 1.25x is really only made for the 2048 units used in D-Cinema. You could use a 1.25x in the home, but you would need custom scaling where the 1.33x lenses will work with the simple letterbox and 4 x 3 modes.

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post #607 of 630 Old 04-04-2012, 07:48 PM - Thread Starter
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Quote:
Originally Posted by CAVX View Post

The other thing to consider too is that the ISCO III being 1.33x, was designed to work with HT projection where the ISCO 1.25x is really only made for the 2048 units used in D-Cinema. You could use a 1.25x in the home, but you would need custom scaling where the 1.33x lenses will work with the simple letterbox and 4 x 3 modes.

And that and what Getgray said was why I think he was complaining about the Isco 3L in the first place. Ive seen it in front of several true 4k projector an the pic is stunning. There is no way that even the finest most perfectly aligned 3 chipper beats the Isco 3L when it comes to chromatic abberation. I seen several people comment on the CA when the Isco is in the light path. Of course you do, because your stretching he picture 33% so you notice it more at the edge. Now take the ISCO away and guess what? You have CA you never noticed before. That's why there's nothing like a one chip DLP. It still my favorite, but I cant give up the contrast of my RS40. The other thing people confuse/interpret the increase in pixel density and the smoother picture as a loss of focus, when in fact the picture is better. Viewing true 4k for the last four CES and true 8k this last one was a revelation. The picture is become more analog/organic which is huge benefit. So one thing the top commercial and residential theaters all have in common, Cylindrical Anamorphic Projection and that will continue with higher res projectors.
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post #608 of 630 Old 04-07-2012, 01:45 AM
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Quote:
Originally Posted by coolrda View Post

The other thing people confuse/interpret the increase in pixel density and the smoother picture as a loss of focus, when in fact the picture is better.

A massive PLUS ONE on that

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post #609 of 630 Old 04-10-2012, 05:39 AM
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A-lens or not decisions decisions........14`.2" throw 1.97 TR.

JVC RS65 (X90) 3m white 1.2 gain screen 108hours Calibration at 250hrs. Resized only.


Arts Sim HT5000 + A-Lens 4.25m screen
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post #610 of 630 Old 04-10-2012, 07:03 AM
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Quote:
Originally Posted by Kevin 3000 View Post

A-lens or not decisions decisions........14`.2" throw 1.97 TR.

JVC RS65 (X90) 3m white 1.2 gain screen 108hours Calibration at 250hrs. Resized only.


Arts Sim HT5000 + A-Lens 4.25m screen

You could combine the JVC and anamorphic lens. I have an RS55 with an Isco 3 on a 135" wide 2.35:1 Enlightor 4K screen - my first row is at about .85 SW and I love the effect of the e-shift and anamorphic lens at that close distance. In my tests it seemed that the benefits of e-shift diminished once you reach 1-1.2SW depending on the quality of the source and the screen material.

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post #611 of 630 Old 04-10-2012, 09:10 AM
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Quote:
Originally Posted by HogPilot View Post

You could combine the JVC and anamorphic lens. I have an RS55 with an Isco 3 on a 135" wide 2.35:1 Enlightor 4K screen - my first row is at about .85 SW and I love the effect of the e-shift and anamorphic lens at that close distance. In my tests it seemed that the benefits of e-shift diminished once you reach 1-1.2SW depending on the quality of the source and the screen material.

Thanks for the reply Hogpilot
Your A-lens is giving you more lumens needed for your 3.4m screen which is good if needed but what else is the A-lens doing to improve the picture?
If extra lumens are not required, menus visible all good but is the picture quality something you can photograph to show A/B comparisons or is it more like a perceptual improvement?
The 6million odd e-shifted pixels and no SDE remaining without the A-lens and lower lumens degrade picture quality enough to buy the A-lens?

Just trying to understand, i can purchase an A-lens with a 2 week full refund if needed but to save the hassle hear i am, extra lumens would be nice as lamp ages but really asking about picture quality..
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post #612 of 630 Old 04-10-2012, 09:18 AM
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It's notoriously hard to appreciate the difference an A lens can make just using photographs (you need the full res available otherwise it's a waste of time), and usually only a demo can provide what's needed.

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post #613 of 630 Old 04-10-2012, 09:23 AM
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Originally Posted by Kevin 3000 View Post

Thanks for the reply Hogpilot
Your A-lens is giving you more lumens needed for your 3.4m screen which is good if needed but what else is the A-lens doing to improve the picture?

I'd say the lumens are the biggest contribution. I haven't had a chance to A/B with and without the lens in my final setup (zoom vs. lens). I have yet to notice any extra CA, but the Isco is about as good as they come in this respect so no surprise here. What's your viewing distance?

Quote:
Originally Posted by Kevin 3000 View Post

If extra lumens are not required, menus visible all good but is the picture quality something you can photograph to show A/B comparisons or is it more like a perceptual improvement?

I would love to take some pics, but I'm currently deployed to the Middle East until July, so unfortunately my theater will be sitting and waiting unused until then Sorry I can't offer more help on this...

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The 6million odd e-shifted pixels and no SDE remaining without the A-lens and lower lumens degrade picture quality enough to buy the A-lens?

Only you can really answer that question, but I'll offer this up - when I was A/B'ing the Enlightor 4K screen material against the Seymour AV CenterStage XD, the 4K clearly had the edge in terms of lack of screen surface visibility, yet my eye was constantly drawn to the image on the XD because it was noticeably brighter. So I guess what I'm saying is not to underestimate the benefit that the extra brightness will give you. Whether or not it's worth the cost...everyone has a different answer as to how much money is "enough" - hence the rather heated debates on the subject in this forum

Quote:
Originally Posted by Kevin 3000 View Post

Just trying to understand, i can purchase an A-lens with a 2 week full refund if needed but to save the hassle hear i am, extra lumens would be nice as lamp ages but really asking about picture quality..

I would say that extra brightness contributes to PQ significantly. Since you have the 2-week grace period, I'd recommend you give the lens a shot and see if you like the result. If you don't, at least you're not out any money.

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post #614 of 630 Old 04-10-2012, 09:28 AM
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Quote:
Originally Posted by Gary Lightfoot View Post

It's notoriously hard to appreciate the difference an A lens can make just using photographs (you need the full res available otherwise it's a waste of time), and usually only a demo can provide what's needed.

Gary

+1! Couldn't agree more...

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post #615 of 630 Old 04-10-2012, 09:48 AM
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Originally Posted by HogPilot View Post

+1! Couldn't agree more...

Thanks for being there for us, Hog. Fly safe. May I use your Isco 3 while your away?
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post #616 of 630 Old 04-10-2012, 10:33 AM
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Thanks Hogpilot i do sit 1SW back, looks like i will have to see for myself. Prismasonic Finland must be confident giving 2 weeks grace if disappointed, i will check again though.
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post #617 of 630 Old 04-10-2012, 10:56 AM
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Thanks for being there for us, Hog. Fly safe. May I use your Isco 3 while your away?

Sure, just fix the inop slide for me while you're at it and we'll call it even It's a re-branded Panamorph slide, which may be part of the problem...

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post #618 of 630 Old 04-10-2012, 12:07 PM
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Quote:
Originally Posted by Kevin 3000 View Post

Thanks Hogpilot i do sit 1SW back, looks like i will have to see for myself. Prismasonic Finland must be confident giving 2 weeks grace if disappointed, i will check again though.

Be sure and start a thread with your impressions, please. I'd sure like to hear them, and I'm sure others would.

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Sure, just fix the inop slide for me while you're at it and we'll call it even It's a re-branded Panamorph slide, which may be part of the problem...

Motorized, I presume.?
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post #619 of 630 Old 04-10-2012, 01:16 PM
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Motorized, I presume.?

Yes indeed. And I didn't mean to insinuate that Panamorph makes sub-par equipment; quite the contrary, my personal opinion is that their stuff is by far the best bang for your buck in terms of price/performance ratio.

However I don't think that the slide was meant to handle the heavier weight of an Isco 3, hence my suspicion that the motor may be burnt out. However it may be more than that - the unit won't even turn on, so it may be something on one of the small circuit boards under the cover. I meant to send it away to a guy over on Curt Palme's forum so he could look at it before I left, but I ran out of time so it will have to wait until I get back. Or maybe I'll just trade up to a CineSlide...

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post #620 of 630 Old 04-11-2012, 03:37 AM
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Quote:
Originally Posted by HogPilot View Post

Yes indeed. And I didn't mean to insinuate that Panamorph makes sub-par equipment; quite the contrary, my personal opinion is that their stuff is by far the best bang for your buck in terms of price/performance ratio.

However I don't think that the slide was meant to handle the heavier weight of an Isco 3, hence my suspicion that the motor may be burnt out. However it may be more than that - the unit won't even turn on, so it may be something on one of the small circuit boards under the cover. I meant to send it away to a guy over on Curt Palme's forum so he could look at it before I left, but I ran out of time so it will have to wait until I get back. Or maybe I'll just trade up to a CineSlide...

With your JVC is there a need for a slide with these menu options?

Manual quotes
Anamorphic The video images are projected after being enlarged in the vertical direction of the panel
resolution. This setting is used when one uses the anamorphic lens to enlarge them in the
horizontal direction.
If a 3D signal is fed in when Anamorphic mode is set to A or B, Anamorphic mode is
automatically turned Off.
Settings: A, B, Off [Off]

A: Video with an aspect ratio of 2.35:1 is enlarged in the vertical direction of the panel resolution and then projected.

B: Video with an aspect ratio of 16:9 are displayed by reducing them in the horizontal direction, without changing their size in the vertical direction.

Off: Used when watching video images other than those with a 2.35:1 aspect ratio while using an anamorphic lens. 2.35:1 video images are projected without any changes. (Black bands appear on all sides)
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post #621 of 630 Old 04-11-2012, 09:28 AM
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Quote:
Originally Posted by Kevin 3000 View Post

With your JVC is there a need for a slide with these menu options?

Manual quotes
Anamorphic The video images are projected after being enlarged in the vertical direction of the panel
resolution. This setting is used when one uses the anamorphic lens to enlarge them in the
horizontal direction.
If a 3D signal is fed in when Anamorphic mode is set to A or B, Anamorphic mode is
automatically turned Off.
Settings: A, B, Off [Off]

A: Video with an aspect ratio of 2.35:1 is enlarged in the vertical direction of the panel resolution and then projected.

B: Video with an aspect ratio of 16:9 are displayed by reducing them in the horizontal direction, without changing their size in the vertical direction.

Off: Used when watching video images other than those with a 2.35:1 aspect ratio while using an anamorphic lens. 2.35:1 video images are projected without any changes. (Black bands appear on all sides)

I haven't personally played with that feature (my Lumagen Radiance does all the processing), but yes it sounds like you are correct, no need for a slide if you want to use the JVC's built-in scaling functions.

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post #622 of 630 Old 04-12-2012, 06:45 AM
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Am i right in thinking with an A-lens I leave my pic in 16:9 mode (mid zoom) let the A-Lens fill the screen gaining 12,500 on/off CR (X90) + 25% Lumens 425?

Cine4home table:
-------------Zoom IRIS Lumens X70 X90
High / D65 Max Closed 370 53000:1 80000:1
High / D65 Min Closed 310 69000:1 105,000:1
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post #623 of 630 Old 04-12-2012, 08:21 AM
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Quote:
Originally Posted by Kevin 3000 View Post

Am i right in thinking with an A-lens I leave my pic in 16:9 mode (mid zoom) let the A-Lens fill the screen gaining 12,500 on/off CR (X90) + 25% Lumens 425?

Cine4home table:
-------------Zoom IRIS Lumens X70 X90
High / D65 Max Closed 370 53000:1 80000:1
High / D65 Min Closed 310 69000:1 105,000:1

You'll maintain the CR, but you won't "gain" lumens - you'll still only have the quoted number of lumens, you just won't lose any to the overspill you'd have if you were zooming.

The only time you "gain" light output from using an anamorphic lens in numerical terms is when you're measuring light off the screen in foot-Lamberts, since that measures light per unit area.

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post #624 of 630 Old 01-08-2015, 01:35 PM - Thread Starter
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Its been along time since I posted here but I must say that my lens continues to hold its value to me. New dedicated theater in a new home with a new projector and new screen but despite all of this I remain using the A lens. At least for me, resolution or pixel count doesn't change anything. The lens transparently passes the pixels. Auto zoom is cool and may be my choice over a prism but having played with different setups I still prefer the lens. I will however for the first time look to getting a Cineslide as 4K comes in the two flavors, 3840 and 4096. 4096x2160 is scaled to 3840x2025 which looks kinda goofy window boxed. So I'll use the lens for ALL widescreen content. The quality of 4k content is from better than 1080P to flawless as when the file sizes are 10+gb. Tears of Steel is a good example of what uncompressed can do. They even have a DCP file. Theres some 4k 2.35 content but I haven't run across any anamorphic yet.
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post #625 of 630 Old 01-15-2015, 08:34 PM
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Quote:
Originally Posted by coolrda View Post
Its been along since I posted here but I must say the my lens continues to hold its value to me. New dedicated theater in a new home with a new projector and new screen but despite all of this I remain using the A lens. At least for me, resolution or pixel count doesn't change anything. The lens transparently passes the pixels. Auto zoom is cool and may be my choice over a prism but having played with different setups I still prefer the lens. I will however for the first time look to getting a Cineslide as 4K comes in the two flavors, 3840 and 4096. 4096x2160 is scaled to 3840x2025 which looks kinda goofy window boxed. So I'll use the lens for ALL widescreen content. The quality of 4k content is from better than 1080P to flawless as when the file sizes are 10+gb. Tears of Steel is a good example of what uncompressed can do. They even have a DCP file. Theres some 4k 2.35 content but I haven't run across any anamorphic yet.
The loyal hardcore are still in the club. My preference for screen size for an anamorphic release is about 42 degrees. This is something of a personal curse from the movie business; the need to "keep my arms around" the image so I can study the frame/framing best. This puts me at about 1.4 to 1.5 screen width, which is just starting to reach the limits of 1080p. For this reason, I don't think that 4K resolution will be a big need, but the other benefits of UHD will be nice. It also means that I'll probably always be able to enjoy CenterStage XD.

I also have always liked the lack of futzing one has with an A-lens. Once it's done right, it's a great convenience as well as a gorgeous image.
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post #626 of 630 Old 01-30-2015, 05:44 AM
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has anyone tried a prime A-lens, say the ISCO III S/L on a native 4K projector, such as the Sony one with 2.35 content ?
All these posts have lots of info, but as they go far back, it's difficult to say if anything's been tested for 4K.


Cheers
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post #627 of 630 Old 01-30-2015, 06:32 AM
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Quote:
Originally Posted by Eksohek View Post
has anyone tried a prime A-lens, say the ISCO III S/L on a native 4K projector, such as the Sony one with 2.35 content ?
All these posts have lots of info, but as they go far back, it's difficult to say if anything's been tested for 4K.


Cheers
Ekso
Esko:
First, yes, I know the XEIT is being used extensively on Sony 4k's. I've had several customers with Schneider on 4k as well. Second, note that the Isco III S/L are no more. They are now branded Schneider M/XL. Same glass, made in the same place by the same people, just a different case for the glass.
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post #628 of 630 Old 01-30-2015, 04:55 PM
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One of the main problems with Sony 4K projectors - as far as anamorphic lenses are concerned - is that the projection lens in the Sony is 35mm recessed into the case. This means that the beam is pretty fat by the time it clears the case. Throw ratios need to be longer, especially where tilting of the anamorphic lens is required, in order to avoid vignetting. TRs of around 1.9 and up are advisable.

In taking into account the minimum TR required, it's not just a simple calculation of projector distance versus screen height that's necessary.

As most 'scope movies today are of 2.40:1 aspect ratio - 800 pixels high - when they are digitally vertically expanded by exactly 4/3 (1.33x) prior to anamorphic horizontal expansion, the full pixel height of the projector panel is not used. 800 x 1.33 equals only 1067 pixels. There is a sliver of black at the top and bottom of the screen around 8 pixels high. Inserting a "fudge factor" of around a quarter to half an inch so that the image can bleed a little onto the masking, the TR is consequently reduced. With all anamorphic lenses, of all brands - prismatic or cylindrical - there is also a slight reduction in height due to refraction of the beam as it passes through the optically unpowered vertical plane of the glass. This is a constant amount no matter what the size of the image, but in critical areas needs to be taken into account.

At Xeit we have a spreadsheet model that accurately calculates and reflects all these extra factors in order to deliver a true indication of practical zoom factor required to fit the screen exactly, without under or over-shoot. Our web site also contain a full suite of test patterns for accurate fitting of the image to the screen.

In such critical situations we perform the calculation so that there are no unpleasant surprises on installation day, especially if the site is thousands of kilometres away in an overseas job. This spreadsheet also calculates pincushion that will be produced and the correct curvature of screen to get rid of it exactly. For even more critical calculations, the results from this spreadsheet can be fed into an optical modelling software package for sub-millimetre accuracy and pixel-by-pixel examination of the image at any point on the screen.

I used this modelling recently on a particularly tricky installation. I gave the curvature required as 41'3.5", and advised the systems integrator to use a stock "40-foot" curvature screen. Imagine my surprise next day when he phoned me back wanting to know whether the ".5" in "3.5" was critical! They were actually going to build a custom curved screen on-site, to the exact specifications I had provided. In the end it worked perfectly, exactly as predicted. It took a week to build and stretch the screen, then to mount it. The screen maker slept on site until the job was finished. He kept calling me back asking whether I was sure about the dimensions as he thought the curvature (depth of sagitta) would be too much. But I stuck to my guns and it all came out well.

As far as "4K" compatibility is concerned, Xeit lenses are calibrated and tested out to "6K" standards, so that they are certified to definitely cope accurately with 4K projectors, as well as delivering the well-known Xeit lower horizontal distortion factors (i.e. less stretching at the sides and hence better overall evenness of illumination), zero color aberration or ghosting, infinite focusability (no "corrector" lenses, no focus steps or focus "sweet spots"), and no color cast when inserted into the beam. As Get Gray attests, they have been used many times with Sony 4K projectors.
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Last edited by Aussie Bob II; 01-30-2015 at 05:01 PM.
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post #629 of 630 Old 02-08-2015, 10:51 PM - Thread Starter
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I built a DIY curved screen which is a topic for another time. Just wanted to mentioned that I used AB2's curved screen calculator and was skeptical of the 30.7ft radius it calculated that I would need. Well, it nailed it. Sagitta was dead on. Props to you, Aussie Bob.
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post #630 of 630 Old 02-12-2015, 04:57 AM
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Why, thank you Cooldra.

I had a similar, if vicarious experience recently when an installer/integrator asked me for a calculation of the curvature needed for a prestige installation. I came back to him saying, "41 feet 3-and-a-half inches, make it 40 feet."

A day later he replied asking if the "half inch" in "three and a half inches" was critical. It was only then that I realized he was going to have the screen built on site by Oz Theater screens.

Rich from Oz Theater camped on site for a day or so and built the screen. Like you he was sceptical of the recommended sagitta (the sagitta is the depth of the curvature at the center of the screen), but I told him to just go ahead.

Turned out it worked perfectly.

A 40 footer would have had a tiny, say 1 or 2mm pincushion, not really noticeable, and would probably have been a lot cheaper than a custom build, but the customer was fastidious. It was a whopping big screen, 160 inches, with quite a short throw, using a Wolf Cinema projector which had been purchased specially by wolf direct for the job.

All's well that ends well. You can't argue with the physics, even though it seems to be all wrong (Global Warming deniers please note).

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