A-lens that can work on my HT? - AVS Forum
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post #1 of 13 Old 08-07-2013, 04:05 PM - Thread Starter
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Hello

I just upgrade to JVC X35. I'm now with maximum zoom to fill my screen so may be i'll need A-lens soon or later.
My screen is 152" and the throw distance is 5m. Thats the best i can do because my room is 5.45m long

So my question is if there is any A lens that can work on my short set up?
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post #2 of 13 Old 08-07-2013, 06:11 PM
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Yes, pretty much any of the larger anamorphic lenses like the Isco III, Panamorph CineVista, UH480 or DC1 will work. You will just have a fair amount of pincushion to correct for.

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post #3 of 13 Old 08-09-2013, 12:59 PM - Thread Starter
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Thats good. the JVC has an option to correct the pincushion.
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post #4 of 13 Old 08-10-2013, 01:27 AM
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I have an X35 and use an Isco II lens (I'm at a very long throw, so can get away with this). I have played with the X35 pincushion control and IMVHO it causes artifacts such as jagged diagonal lines when used. While I don't need to use the feature myself since my pincushion is tiny I was just playing about with the settings when I got it last year, so I wouldn't plan to use it as a permanent fix if I were you...ultimately you will likely need a curved screen since I doubt you'll be able to get away with slightly overspilling as I do. frown.gif

I should add that I'm in the group who would never use electronic keystone for the same reasons, though I know some people don't seem to be bothered by the side effects; they prefer to have correct geometry above absolute picture quality.

Zooming: Been there, done that, bought the lens...
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post #5 of 13 Old 08-10-2013, 08:29 AM
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I agree with Kelvin1965S above - you probably want to avoid the pincushion correction and overscan into your screen's black border instead.

However, thinking about this, you should not have too much pincushion if your screen is 152" diagonal (vs. 152" wide). Your throw distance of 5 meters is about 16 and a half feet. I have my projector installed about 17.5' back from a 144" screen and my pincushion is minimal. How tall is your screen? If it is 5' tall, your minimum throw would be 3X screen height, which gives you a recommended minimum throw distance of 15' back or greater. You will have some pincushion but not an outrageous amount.

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post #6 of 13 Old 09-21-2013, 01:36 PM - Thread Starter
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Well i cannot spend more then 1000$ for A-lens. So i need to hunt a B-stock (scratch box or something) of U480 or to buy CineVista (which as far as know has some limits of showing the colors correctly). I read that the JVC can handle this so its not a big problem + that the problem its not much visible...

But then the other unknown is after 2-3 years how this Lens will handle the 4K, when I decide to jump 4K PJ...
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post #7 of 13 Old 09-22-2013, 02:32 AM
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Please note that the X35 does not have the multizone pixel adjustment that the Cinevista lens will require. For this you would need to use the X55 or perhaps another make of projector such as the Sony VW50ES.

I'm sure John will correct me if wrong, but I think that the Cinevista isn't really the lens to be looking at if you plan to move to 4K with it: It's a budget lens with various limitations (as per above) but which enables users to get into lens ownership.

Zooming: Been there, done that, bought the lens...
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post #8 of 13 Old 09-22-2013, 08:22 AM - Thread Starter
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Yep. I'll not buy anything until i'm sure it will 100% working. You know how is it.. with every day you want more and more from your HT and this never stop. I suppose there will be a new range A-lens fully supporting 4K... of course we're talking about the next 1,2,3,4 years :P
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post #9 of 13 Old 09-24-2013, 08:49 AM
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Quote:
Originally Posted by Kelvin1965S View Post

Please note that the X35 does not have the multizone pixel adjustment that the Cinevista lens will require. For this you would need to use the X55 or perhaps another make of projector such as the Sony VW50ES.

I'm sure John will correct me if wrong, but I think that the Cinevista isn't really the lens to be looking at if you plan to move to 4K with it: It's a budget lens with various limitations (as per above) but which enables users to get into lens ownership.

You are correct that the X35 does not have the multizone pixel adjustment. While I would not say that the CineVista "requires" it, it does help the CineVista give the very best performance (Panamorph has many CineVista owners that use it with DLP projectors, which have no multizone correction, and they are quite happy). However, I would agree that someone who is concerned enough about 4K to be planning for the future would want to make sure that whatever 4K projector they end up with will have correction capabilities.

As far as the CineVista itself, it performs in most ways the same as our own UH480, only without correction for chromatic aberration (which most people don't notice anyway). For critical viewers who are conscious of chromatic and look for it, they will probably be much happier with either one of our higher end lenses or with a projector that has panel correction. Regarding 4K, the CineVista is certainly capable, with the caveat that you would want color correction built into your projector to compensate for the chromatic aberration. Perhaps the best way to think of the aberration is to say it’s similar to convergence or misalignment error. All three color images are sharp but misaligned. That shouldn’t be confused with focus error even though misalignment might be perceived as blurring. Having chromatic correction built into the projector takes care of this problem.

While the JVC X35 does not have the correction capabilities, it is likely that any 4K projector in your future would.

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post #10 of 13 Old 09-24-2013, 09:24 AM
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Quote:
Originally Posted by John Schuermann View Post

Regarding 4K, the CineVista is certainly capable, with the caveat that you would want color correction built into your projector to compensate for the chromatic aberration.

That's something I've been wondering, maybe you can shed some light. I keep seeing references to people saying you need a "special" lens for 4K. What's different in the design criteria for 4k vs 1080p for a lens?

I mean I look at my HD5000 lens on my 1080p DLP and all the pixels are cleanly resolved, so logically I don't see how it would "not work" or even "seriously degrade" the image of a 4k machine.

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post #11 of 13 Old 09-24-2013, 04:04 PM
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Originally Posted by stanger89 View Post

That's something I've been wondering, maybe you can shed some light. I keep seeing references to people saying you need a "special" lens for 4K. What's different in the design criteria for 4k vs 1080p for a lens?

I mean I look at my HD5000 lens on my 1080p DLP and all the pixels are cleanly resolved, so logically I don't see how it would "not work" or even "seriously degrade" the image of a 4k machine.

I'm not the optical engineer at Panamorph, but as I understand it, it's simply a matter of whether or not the pixels will resolve clearly at 4K resolutions, just like what you are seeing with your DLP. It's simply a matter of the quality of the glass, just like a cloudy piece of glass obstructs your view out a window. As long as the optics will resolve those pixels clearly, you are ok for 4K. The CineVista will resolve the pixels clearly, you just have the issue of the color separation that can be corrected with the methods we have been discussing.

Here is something that many people don't understand about 4K. Getting 4K material that REALLY shows off the fine detail that 4K is capable of means a whole bunch of things need to come into play:

A camera (film video or still) that is capable of truly capturing 4K resolution.

Optics for the above camera capable of resolving that kind of fine detail. Just think about how a fog filter softens the image, or how Geoffrey Unsworth used to smear the camera lens with vaseline to get the "gauzy" look he so much liked. Use those methods and your chances of getting fine "4K level" detail are incredibly diminished.

Subject matter that has the level of fine detail you can make out with 4K (shooting smooth surfaces, for example, will not look any sharper at 4K then at 1080P).

Camera focus. This is a HUGE consideration. I have worked on several features shot at 4K. One of the things that is amazing is how an image that looks sharp on the camera monitor or viewfinder can appear to be slightly out of focus when you blow it up to 4K level. We spent some time looking at 4K footage for a demo disc for our MFE process and it was amazing how little 4K footage actually could show off the true difference 4K is potentially capable of. A shot that is even *slightly* out of focus destroys all of the extra fine detail. At 1080P (or even 720P), the image looks nice and sharp, but blow it up to 4K and you start noticing focus deficiencies. Of course, to even see those focus deficiencies, you need to be seated VERY close to the screen (which brings us around to the whole "is 4K even necessary" argument).

Camera stability. This is another huge consideration, as even slight camera instability and shaking also destroys the ability to capture fine detail. This is why all of the 4K demos at CES and CEDIA are invariably incredibly static shots, with the camera locked down so it can't even move a fraction of a millimeter (and the camerapersons are probably holding their breath as well). You also notice that the subject matter is usually objects with incredibly fine levels of detail, such as fabric weaves or intricate patterns. With everyday footage the difference between 2K and 4K is very hard to spot.

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post #12 of 13 Old 09-24-2013, 04:11 PM
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I thought I would post this, since it may be interesting to film / movie buffs here on this forum. I did a bunch of research a couple of years ago regarding film vs. digital resolution, and to determine what the actual resolution of 35mm film is. As many here probably know, 35mm film is theoretically a very high resolution medium. And, if you look at 35mm film frame by frame, that is actually the case. But when you project that same film - even with a very stable film projector - a large percentage of the actual resolution goes right out the window. Why? Projector film gate judder. This goes right to the point I made above about how capturing 4K levels of detail requires a locked down camera.

A rather large international study was undertaken a few years ago to test the actual resolution of film as compared to digital, by seeing how well film under ideal circumstances resolved detail using a specially created resolution pattern. The results were that an actual answer print had an effective resolution of about 1400 lines, with the release print having about 1000 lines. However, when the films were actually projected in state of the art commercial cinemas chosen by the test group, the visible resolution on screen dropped to an average of around 750 lines, the very best being around 875 lines. The main reason the resolution dropped so drastically was due to film judder in the projector gate. And this was using the very best projectors available using ideally prepared prints. So, DCI and Blu-ray have the capability of looking better than even the very best theatrical presentation of 35mm.

Here is a link to the study itself: http://www.cst.fr/IMG/pdf/35mm_resolution_english.pdf

Another test was to compare 70mm to 4K digital hosted by the Digital Cinema Society, with a theater full of cinematographers. This is from a report written by Howard Hall, a guy who shot lots of IMAX and 70mm undersea footage. The conclusion from the shootout? "When the audience was asked which image they liked best, the overwhelming response was that they preferred the digital projection. As an IMAX 70mm veteran, I found that quite astounding." Here is his report, if you care to read it for more technical details:

The “shootout” between 70mm and 4K was most interesting. We saw two clips projected via split screen then we saw the clips projected alternately. The first 70mm clip from “Pulse” was printed in the traditional way via negative, interpositive, and duplicate negative. The second 70mm clip (from Wild Ocean) was made in the more modern way via 11K scan from negative, then a 4K down-conversion, then film-out to 70mm. The digital projections were made via 11K scan and then 4K down-conversion. The 4K file of Wild Ocean was the file used for the film-out.

Just comparing the two 70mm clips was enlightening. The “Pulse” clip was significantly better than the film-out version of Wild Ocean. Scanning and film-out of Wild Ocean had been necessary because so many different formats in addition to 70mm were used in original image capture (we saw only 70mm original capture examples). Andrew Orin from FotoKem who made the film prints, estimated that even the “Pulse” clip had degraded to between 5.5 and 6K via the printing process (assuming original camera negative is about 11K).

In my opinion the split screen comparison showed that 4K projection is equal to or better than 70mm projection in all respects save one. The digital images appeared as sharp or sharper, they appeared to have more contrast in addition to equal or better resolution, and the color saturation and fidelity was equal or better. These differences were minor and debatable when the two “Pulse” clips were compared. The differences were dramatic when Wild Ocean was up.

The only remaining advantage to the 70mm projection was that the 4K projection was 16x9 and did not fill the vertical axis of the screen. That the bottom of the 4K screen image was missing was of no consequence to me since audience heads occlude the 70mm image at the bottom and to me this may be viewed as a distraction. The top of the screen is another story however. Some of the experiential effect is lost with the 4K projection though I confess I did not miss it much. This was the only disadvantage to 4K digital capture and projection that I could see and was but one point when scored against the myriad disadvantages, both financial and logistical, of shooting and projection in 70mm.

When the audience was asked which image they liked best, the overwhelming response was that they preferred the digital projection. As an IMAX 70mm veteran, I found that quite astounding.

John Schuermann, Filmmaker / Film Composer
Home Theater Industry Consultant
JS Music and Sound
Panamorph
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post #13 of 13 Old 09-24-2013, 05:30 PM
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Quote:
Originally Posted by John Schuermann View Post

I'm not the optical engineer at Panamorph, but as I understand it, it's simply a matter of whether or not the pixels will resolve clearly at 4K resolutions, just like what you are seeing with your DLP. It's simply a matter of the quality of the glass, just like a cloudy piece of glass obstructs your view out a window. As long as the optics will resolve those pixels clearly, you are ok for 4K. The CineVista will resolve the pixels clearly, you just have the issue of the color separation that can be corrected with the methods we have been discussing.

Intuitively, that's how I would expect/describe it. Further, intuitively again, I would say that if you look at a 1080p machine through a lens, and you can clearly make out the edges, and even the interpixel gaps (which are far, smaller in scale than even a 4k pixel), that that lens could be classified as "4k ready".

Yet at the same time I've seen numerous posts here by those who I trust the opinions of stating or implying (and maybe I'm reading the wrong things into comments) that there aren't any lenses currently available that are "good enough" for 4K, not even the mighty ISCO III.
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Here is something that many people don't understand about 4K. Getting 4K material that REALLY shows off the fine detail that 4K is capable of means a whole bunch of things need to come into play

Yeah, even for the best, the reference content, I'm starting to think that we really need 4K displays just to get the best out of 1080p sources
Quote:
Originally Posted by John Schuermann View Post

I thought I would post this, since it may be interesting to film / movie buffs here on this forum. I did a bunch of research a couple of years ago regarding film vs. digital resolution, and to determine what the actual resolution of 35mm film is. As many here probably know, 35mm film is theoretically a very high resolution medium. And, if you look at 35mm film frame by frame, that is actually the case. But when you project that same film - even with a very stable film projector - a large percentage of the actual resolution goes right out the window. Why? Projector film gate judder. This goes right to the point I made above about how capturing 4K levels of detail requires a locked down camera.

A rather large international study was undertaken a few years ago to test the actual resolution of film as compared to digital, by seeing how well film under ideal circumstances resolved detail using a specially created resolution pattern. The results were that an actual answer print had an effective resolution of about 1400 lines, with the release print having about 1000 lines. However, when the films were actually projected in state of the art commercial cinemas chosen by the test group, the visible resolution on screen dropped to an average of around 750 lines, the very best being around 875 lines. The main reason the resolution dropped so drastically was due to film judder in the projector gate. And this was using the very best projectors available using ideally prepared prints. So, DCI and Blu-ray have the capability of looking better than even the very best theatrical presentation of 35mm.

Here is a link to the study itself: http://www.cst.fr/IMG/pdf/35mm_resolution_english.pdf

Yeah, I remember seeing that, and talking about that here a few years ago. Though I remember thinking the takeaway was that the drop in resolution was due to the degradation of the film over use and multiple generations of copies, though I'm sure the judder would make a difference too.

And yeah, I've seen it myself, despite the theoretical superiority of 35mm, digital projection was the best thing to happen to (cinema) movie projection around where I live, the quality, and consistency dramatically increased with the move to DCI here.
Quote:
Another test was to compare 70mm to 4K digital hosted by the Digital Cinema Society, with a theater full of cinematographers. This is from a report written by Howard Hall, a guy who shot lots of IMAX and 70mm undersea footage. The conclusion from the shootout? "When the audience was asked which image they liked best, the overwhelming response was that they preferred the digital projection. As an IMAX 70mm veteran, I found that quite astounding." Here is his report, if you care to read it for more technical details:

The “shootout” between 70mm and 4K was most interesting. We saw two clips projected via split screen then we saw the clips projected alternately. The first 70mm clip from “Pulse” was printed in the traditional way via negative, interpositive, and duplicate negative. The second 70mm clip (from Wild Ocean) was made in the more modern way via 11K scan from negative, then a 4K down-conversion, then film-out to 70mm. The digital projections were made via 11K scan and then 4K down-conversion. The 4K file of Wild Ocean was the file used for the film-out.

Just comparing the two 70mm clips was enlightening. The “Pulse” clip was significantly better than the film-out version of Wild Ocean. Scanning and film-out of Wild Ocean had been necessary because so many different formats in addition to 70mm were used in original image capture (we saw only 70mm original capture examples). Andrew Orin from FotoKem who made the film prints, estimated that even the “Pulse” clip had degraded to between 5.5 and 6K via the printing process (assuming original camera negative is about 11K).

In my opinion the split screen comparison showed that 4K projection is equal to or better than 70mm projection in all respects save one. The digital images appeared as sharp or sharper, they appeared to have more contrast in addition to equal or better resolution, and the color saturation and fidelity was equal or better. These differences were minor and debatable when the two “Pulse” clips were compared. The differences were dramatic when Wild Ocean was up.

The only remaining advantage to the 70mm projection was that the 4K projection was 16x9 and did not fill the vertical axis of the screen. That the bottom of the 4K screen image was missing was of no consequence to me since audience heads occlude the 70mm image at the bottom and to me this may be viewed as a distraction. The top of the screen is another story however. Some of the experiential effect is lost with the 4K projection though I confess I did not miss it much. This was the only disadvantage to 4K digital capture and projection that I could see and was but one point when scored against the myriad disadvantages, both financial and logistical, of shooting and projection in 70mm.

When the audience was asked which image they liked best, the overwhelming response was that they preferred the digital projection. As an IMAX 70mm veteran, I found that quite astounding.

Interesting, makes me even more excited for 4K biggrin.gif

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
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