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Quote:
Originally Posted by coolrda /forum/post/18924521


Does this lens have correction for focus in relation to T.R.?

All the current cylindrical lenses have adjustable optics so you can get the image sharp corner to corner.

Quote:
With pincushion being the only major aberration that I would like corrected I assume that both issue could be handle with curving the screen at the right radius. As I have no experience in using curved screens, doesn't use of a curved screen help light uniformity across the screen?

To correct pincushion "optically" for use on a flat screen would require a special lens that progressively magnifies to the centre of the image to counter the effects of progressive optical magnification at the edges. Whilst I am sure this can be done, I think that you would find that the lens needed for such a correction would be "throw precise" and not a lens that could be used on many throws. So now, not only would TR be of concern, the actual distance from screen to projector would also come in to play.


The curved screen does this by bringing the edges of the screen closer to the projector. Take any movable surface and project onto that. As you move it closer to the projector, the image size reduces. The curve works in much the same way, except that because the edges are closer than the centre, only the edges are reduced.


So where pincushion expands towards the ends of the screen, the curve now forces the image to be reduced towards the edges. If the curve if correct, two equal but opposite attributes now cancel and you have an image with straight lines.


Does that make sense?
 

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Quote:
Does this lens have correction for focus in relation to T.R.?

No. It has focus correction for absolute throw distance. TR is relatively immaterial, once the focus for throw is set. Focus for a new TR (with the same throw) might change a bit, a fraction of a mm, but not so you'd bother.

Quote:
All the current cylindrical lenses have adjustable optics so you can get the image sharp corner to corner.

Not quite correct. This should read "sharper corner to corner". No simple design can achieve complete astigmatism elimination in all circumstances. Take a look at a projector lens. They use a lot of elements to achieve edge-to-edge focus, many more than a typical anamorphic lens does.


However, the projector lens might have to be re-focused if TR (zoom ratio) is changed. This is pretty standard procedure across the range of even expensive projectors. Once the projector is re-focused, then you'll find the anamorphic has remained focused without extra adjustment required. You focus the anamorphic once for throw and then vary the projector's focus with changing zoom ratios.


Having said that, the more elements and curved surfaces in play, the better the improvement in anamorphic lens astigmatism performance from edge-to-edge - across the full color spectrum from 400um to 700um - should be.


What you will find with 4-element/4-surface designs is that some parts of the spectrum will be sharp, but at the cost of color aberration. In other words, you can get individual colors sharp, but not so that they register precisely with each other (i.e. one color aligned on top of the others). This is especially true at wide TRs.


My observation (admittedly with a practised, critical eye) of even the hallowed Isco (which does have all 4 air-glass surfaces curved, no plano surface at all) has found this to be exactly the case.

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...this indeed sounds like a World First for the home theatre market.

Probably so. Fair statement.
 

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Discussion Starter · #43 ·
Good input Bob and Mark. I would think that the improvement would be very small. I'd guess smaller than the difference between prism-based and circ-lenses. Now if that was available at the same price as the 3L then it's relevant. Even spending $3K is pushing it for most people. And let's face it, the lack of competition has allow Schneider to corner the market and sells product at what I suspect is a nice margin. And I assume any price-breaks are absorbed at the distributor level. Why should Schneider/Isco budge in this esoteric playground. Now maybe this glass warrants that price, i dont know. What i do know is You can get a very nice telescope for the price of a 3L.


Bob, if I understand you correctly, what your describing is color delay due to optics as opposed to electronics causing this in a projector?
 

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Quote:
Good input Bob and Mark. I would think that the improvement would be very small. I'd guess smaller than the difference between prism-based and circ-lenses. Now if that was available at the same price as the 3L then it's relevant.

The improvement is not small at all. It is quite significant.


As for price, think: "a fraction of the price of a 3L".

Quote:
What i do know is You can get a very nice telescope for the price of a 3L.

Yeah, but you can't use a telescope to project widescreen movies
 

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Scott Horton, techht.com
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Quote:
Originally Posted by Aussie Bob /forum/post/18929568


As for price, think: "a fraction of the price of a 3L".

You know I'm looking forward to seeing it, but to be fair, the Isco IIIS is a "fraction of the cost of the IIIL" too. The IIIL is a LOT larger. Maybe not as much of an issue for longer throws or smaller beam sizes. Now if these 3 new lens options that are starting to appear are a "fraction of the price of the (more comparable IMO) IIIS", now that will be good news for many
. Especially for the popular JVC's with their small beams.
 

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My curiosity is piqued by these two new lenses. I know about Mark's new lens but where can I learn about the one you're speaking of Aussie Bob?
 

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Discussion Starter · #48 ·

Quote:
Originally Posted by Aussie Bob /forum/post/18929568


The improvement is not small at all. It is quite significant.


As for price, think: "a fraction of the price of a 3L".




Yeah, but you can't use a telescope to project widescreen movies

Wow. If that comes to fruition, I am very interested in seeing this lens.
 

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Quote:
The IIIL is a LOT larger. Maybe not as much of an issue for longer throws or smaller beam sizes.

Smaller beam sizes are the future. The whole history of semi-conductor design has been to get real estate to a minimum. Larger chip sizes mean larger focal lengths and bigger lenses. Bigger lenses mean more expense and inflated margins.


Smaller chip sizes mean smaller beams, smaller projectors, and smaller anamorphic lenses required to do the same job.


GetGray and I have had this argument for a long time. He reckons that unless a lens can accommodate a 1.3 TR with a 14 foot screen size in a room the size of a broom closet, it isn't serious (well, I'm exaggerating a little, perhaps a lot, but it's the thought that counts).


My point is that anyone - the vast majority - that does not have this setup is paying for the small minority that do have it. Every time you see your beam occupying a small percentage of real estate in the centre of a huge, heavy, over-priced piece of German (or other) glass, you're paying for something you don't need to pay for: size over quality. You're effectively subsidizing the users who think that bigger is always better, and will - can - pay anything for it.


The concept of quality has been abandoned in favour of lens manufacturers trying to cater for the wishes of the spoilt few, who believe bigger and more expensive MUST be better, making the regular, sensible HT enthusiasts pay for the privilege. Because glass is so costly at the manufacturing level, the manufacturers have to simplify their designs (palming off century-old technology as "future proof") to allow huge size. They provide no guidelines or specifications for use, and trust that price alone will make their product look good. Then there are the dealers, and dealers upon dealers, who all get their pound of flesh out of the hapless end-user. It all adds up to inflated prices for 1920's technology.


No-one who spends X-thousand dollars on a dinosaur is going to admit that they spent too much.
 

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Aussie Bob,


I am in agreement with you. First I want the projector behind me so I favor longer throws. Better optics are achievable with smaller lenses. However it is hard to find medium priced projectors with long throws. The newer Sonys have a shorter max throw than the earlier models. Granted a larger zoom range is somewhat detrimental to prime lens performance but none of the medium priced projectors have throws much greater than 2.2:1 with exception of the JVC and very few if any medium priced projectors have replaceable prime lenses to select the throw range.
 

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Scott Horton, techht.com
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The nice thing about the IIIL is it is future PJ proof. If you get a JVC this year, and in 2 you get a Sim2 C4X, you can expect that it will "fit". Unfortunately, some of the heavy metal companies like Sim2 and DPI either have larger beam sizes, recessed lenses, or both. For those, the IIIL is the ticket.


But for the masses that have the JVC's, the IIIS or it's possible contenders should work fine...
 

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Quote:
If you get a JVC this year, and in 2 you get a Sim2 C4X, you can expect that it will "fit". Unfortunately, some of the heavy metal companies like Sim2 and DPI either have larger beam sizes, recessed lenses, or both. For those, the IIIL is the ticket.

Agreed. But how many people are really going to make that jump? A few, granted, but enough to justify forcing the common herd to effectively subsidize them?


I'm just wondering how long the big monsters will be around?


I'm not trying to get into the D-ILA v. DLP sh-tfight too deeply, but from what I've seen the news small-chip JVCs are pretty spectacular, inexpensive (relatively) and getting better with each new model.
 

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This thread was supposed to be a place that those with a cylindrical anamorphic lens could post their impressions and experiences, yet (and this could be just me) it seems to have become a Lens size pissing competition.


On the topic of chip size, the latest DLP offerings are also small at just 0.65". A considerable reduction to the previous 0.9" chips.
 

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Scott Horton, techht.com
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AFAIK, only the "budget" DLPs are getting the smaller DC3 chip, the larger DC4 chip is still in the more expensive lines i.e. Lumis, Titans, Christie, etc.. The MTF has been measured better on the larger DC4 chip as I recall. But you are right, let's not turn this into a PJ tech thread. Back to round A lenses I mean cylindricals
.


Many will be tickled to have a less expensive alternative to a high end German lens. Particularly those wth more modest budgets and projectors. I'm looking forward to having the time to put them through the paces.


Scott
 

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Discussion Starter · #55 ·

Quote:
Originally Posted by GetGray /forum/post/18932887


The nice thing about the IIIL is it is future PJ proof. If you get a JVC this year, and in 2 you get a Sim2 C4X, you can expect that it will "fit". Unfortunately, some of the heavy metal companies like Sim2 and DPI either have larger beam sizes, recessed lenses, or both. For those, the IIIL is the ticket.


But for the masses that have the JVC's, the IIIS or it's possible contenders should work fine...

Very important point and the reason I decided on the 3L after originally settling on the 3S. For the small difference in price I have major piece of mind and better resale down the road. The 70mm opening would have probably worked for me but not knowing which future projector I'll be moving to or for that matter screen size was the reason for moving to the L. I will soon be moving from an 8ft wide to an 11-12ft wide screen. The new room is twice as wide but only a foot deeper so obviously my throw will change. I'm looking into a curved screen for the first time.


Being in Sacramento for training this week and seeing Inception on the 80ft Imax from 40ft back was eye opening. First, when viewing DMR content you really appreciate how good Imax filmed product is (70mm film or a 2K+ digital scan ala RED, etc should be the minimum). The second thing I took away from the experience is how good my picture is with my 3L. Even when viewing from as close as 6ft from my screen. Even if a product comes along that trumps my lens, I'm gonna be very happy for a very long time, especially if I ever have a Vango or comparable LED/DLP behind it. I must say I've enjoyed the posts here so far.


Lastly, has anyone tested or have come across resources/numbers concerning ANSI contrast with these lenses?
 

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Quote:
Originally Posted by Aussie Bob /forum/post/18920632


Should read "alignment is highly important to equalizing pincushion top and bottom of screen". Pincushion with cylindricals is about the same as with prism lenses. Pincushion improvements require much more complex optics than just using a couple of cylindrical lenses.

Ah, but I wasn't talking about just pincushion, I was talking about geometric distortion overall. Specifically, failing to align the lens caused the image to become mildly trapezoidal and accentuated the pincushion. Proper alignment assures that the image is symmetrical along both axes, and also helps to minimize pincushion.

Quote:
Originally Posted by Aussie Bob /forum/post/18920632


Should read "aligning the lens so that its optical axis is completely normal (i.e. perpendicular) to the light path and centered on the beam is just as critical for some lenses.]"


The more elements in the design that are in the light path, the less critical this alignment (especially horizontal alignment) is. This is because the distribution of curvatures is spread over more glass surfaces.


For example a lens with 4 glass-air surfaces (i.e. not counting cemented surfaces) will have more flexibility in alignment if all four surfaces are curved.


A 4 glass-air surface lens with two flat surfaces will only have the possibility of 2 curved surfaces. These curvatures must, of necessity, be quite steep (as the other two of the four are flat), and alignment problems can ensue with them.


A lens with, say, 6 glass-air surfaces has even more degrees of freedom, and thus more flexibility in alignment.

With respect to the alignment, I probably could have done a better job wording things. When I said parallel, I meant parallel to the central axis of the lens. This could also be expressed as normal to the face of the lens, as you said.


And at the time of my writing, I wasn't aware of any commercially available lenses that were more complex than the ISCOIII, so my statement about alignment being critical was valid for what one could buy. Maybe that will change with this new 5-element lens, but my knowledge of that lens is limited to what's been posted here.
 

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Quote:
Originally Posted by Aussie Bob /forum/post/18935085


Agreed. But how many people are really going to make that jump? A few, granted, but enough to justify forcing the common herd to effectively subsidize them?

The current JVCs have recessed lenses that require the use of the bigger lenses, especially at shorter throws. Do you know/expect that this new cylindrical lens will accomodate the JVCs at shorter throws?
 

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Quote:
Originally Posted by Lawguy /forum/post/18947347


The current JVCs have recessed lenses that require the use of the bigger lenses, especially at shorter throws. Do you know/expect that this new cylindrical lens will accomodate the JVCs at shorter throws?

Please define shorter throws?
 

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I am looking at building a small theater with only 1 row of seating which is approx 10'. If I want to go with a larger screen (say 126") & go with CIH, will I be able to use one of the lenses? I am showing the TR is not large enough on most projectors to handle this (such as the JVC15u).
 

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Quote:
Originally Posted by DLopatin /forum/post/18951315


I am looking at building a small theater with only 1 row of seating which is approx 10'. If I want to go with a larger screen (say 126") & go with CIH, will I be able to use one of the lenses? I am showing the TR is not large enough on most projectors to handle this (such as the JVC15u).

The TR number I am referring to is found by dividing the distance between the screen and the projector's lens by the native 16:9 image width.


How deep is the room?
 
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