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Cylindrical A-Lens Owner's Thread - Page 2

post #31 of 623
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When I had both my ISCO III and Panamorph UH480 and was swapping them back and forth in front of a BenQ W20000, one of the major things that I found was that alignment is highly important to minimizing geometric distortion.

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.

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The first step is to make sure that the projector is as perfectly normal to the screen as possible - any sort of keystoning will cause the pincushion to be lopsided in at least one axis.

Correct.

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After that, aligning the lens so that it is completely parallel to the light path is just as critical. Taking the extra time to do this produced some really stunning pictures with almost no pincushion.

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.

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Theoretically there should be a 33% gain of light with the lens in. I took multiple readings with both lux and fc and came up with 304 w/lens and 294 lumens w/o lens. The small difference is probably because of the differences of 2.35/2.37. There's no measurable light loss with this lens. What this means is that the difference between not using a lens and using one is the same as going from a 92" screen to a 106" and having the same light level. This of course is a huge benefit when counting lumens for large screens.

Wrongly put. Using a lens should "theoretically" be 33% brighter than zooming

There will always be a light loss with an A-lens. You are expanding the image in the horizontal direction by one-third. There's 33.3% light loss straight away. Then there's loss through the lens (due to internal reflection and absorption by the glass surfaces).

On the other hand, with zooming you're expanding the image bioth vertically and hosizontally by one third. The Zoom Method arithmetic is 4/3 x 4/3 = a 16/9 increase in image area. Inverting this number you get the relative zoomed brightness (compared to pre-zoomed brightness): 9/16 (56.25% of the pre-zoomed brightness). However you're also enlarging the image which, with projector zoom lenses, makes the aperture of the lens effectively larger (relative to the shorter focal length of a wide angle zoomed lens). This is equivalent to reducing the f/number, so there less loss than you might think... the f/number of an optical system is the focal length (shorter when zoomed) divided by the (fixed) physical aperture.

Compare this greater light transmission efficiency of a zoomed lens with the light loss from using an anamorphic lens and the final 'scope brightnesses are closer than you might think. An A-lens should still deliver greater bruightness than a zoomed lens, but not by 33.3%... more like 15%-20% (and sometimes they're about line-ball, depending on the projector, throw ratio etc. used). On the other hand, an A-lens will most likely never be dimmer thanthe Zoom Method...

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Another cylinder lens is about to enter the market. Will be able to share details soon.
Top performance. Should put a dent in the market.

Make that "another two" lenses to be available soon.

I understand that at least one these two new lenses will be a lightweight, low-distortion, 5-element design, arranged in 3 groups, which is a much-needed improvement on the traditional Schenider/Isco (and other) 4-element, 2-group designs.
post #32 of 623
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I think a prism lens is a ground lens? At least the high quality lenses are. Maybe not DIY lenses but I would consider the Primasonic lens a quality lens. My reasoning is after a week there have not been that many replies so why not widen the scope of the thread to get more comments?

A prism lens is not regarded as a "ground" lens, even though it needs to be technically ground and polished.

The most perfectly machined and polished prism lens can never achieve the sophistication and flexibility of a cylindrically curved lens built to the same specifications.

A prism is essentially a series of flat surfaces, a "one-dimensional solution" if you like.

By contrast cylindrical lenses have the extra degrees of freedom, the "extra dimension" that curvature provides. The more curved surfaces, the better to "massage" the beam and minimize aberrations. Cylindrically curved lenses can be designed to be virtually any shape or form: bi-convex, bi-concave, plano-convex or concave, meniscus form etc. - or any combination of these (and more).

The focal length of a meniscus lens, for example, can be the same as a plano-concave, but the performance characteristics - in the context of the entire design - can be radically different. You probably wouldn't be able to substitute one for the other, even though the have the same theoretical focal length.

On the other hand a pair of prisms involves tilted, but completely flat surfaces. Not much to work with there. Prism lenses are also quite heavy compared to equivalent cylindrical lenses, as a rule.

Prism lenses (even the very highest quality ones) have severe astigmatism problems, especially at short throws and/or short throw ratios. To fix this astigmatism you need a corrector lens, which is in fact a cylindrical element with very weak power.

In short, on a thread about the virtues and various performance characteristics of cylindrical lenses, discussion of prisms is out of place, except for comparison's sake, but not as part of the main thread discussion.
post #33 of 623
Quote:
Originally Posted by Aussie Bob View Post


Make that "another two" lenses to be available soon.

I understand that at least one these two new lenses will be a lightweight, low-distortion, 5-element design, arranged in 3 groups, which is a much-needed improvement on the traditional Schenider/Isco (and other) 4-element, 2-group designs.

Sounds like something on the "horizon" to look forward to...
post #34 of 623
Interested to see it in action aussiebob.
post #35 of 623
Quote:
Originally Posted by CAVX View Post

Sounds like something on the "horizon" to look forward to...

Mark,

What type of improvement are you talking about? So some company has come up with a lens with more elements but what is the purpose of these extra elements or group? Your the expert. Let us know what is going to be the improvement.

Charles
post #36 of 623
Quote:
Originally Posted by Aussie Bob View Post

I understand that at least one these two new lenses will be a lightweight, low-distortion, 5-element design, arranged in 3 groups, which is a much-needed improvement on the traditional Schenider/Isco (and other) 4-element, 2-group designs.

Quote:
Originally Posted by CRGINC View Post

Mark,

What type of improvement are you talking about? So some company has come up with a lens with more elements but what is the purpose of these extra elements or group? Your the expert. Let us know what is going to be the improvement.

Charles

It was actually AB that mentioned the possible improvement using this extra lens, then again, it might even come down to your screen choice - flat or curved.

So without saying too much, when I got to experience the prototype Horizon lens in June 2008, it had an unusual front lens like nothing I'd seen before on any of the commercial anamorphic lenses available at the time.

Whilst I could add a similar lens to my "4 element/2 group" (same as ISCO/Schneider) design, I don't believe I actually need this extra lens for use on a curved screen such as my own. As it turns out, the curved screen which was originally employed for pincushion correction also (by default) corrects this other aberration. The point is, even on a flat screen, this other aberration is not really noticed and I even watched Star Wars films (R2D2's dome head) looking for it. It doesn't bother the owner of the lens I used for this testing, even at his extremely short throw of just 1.4:1 onto a screen some 3.4m wide.

The point being, if you look long and hard enough, you'll find faults in everything, eventually.
post #37 of 623
Quote:


What type of improvement are you talking about? So some company has come up with a lens with more elements but what is the purpose of these extra elements or group? Your the expert. Let us know what is going to be the improvement.

Generally speaking, the more surfaces in a lens, the better the performance potential, given a good design to start with. Of course, on the other hand, you can have a crappy design with 20 surfaces that doesn't perform as well as a great design with only 6 surfaces. Over-engineering is always something that needs to be kept in mind as a pitfall.

This "other" lens (as I understand it) has an optimization that favours flatter, hence cheaper screens. Geometric distortion is reduced, but not to such an extent that it adversely affects curved screen performance either (if that's the way the user wants to go... more money!). What this reduction in geometric distortion means is that grid squares are more evenly sized right across the screen. Traditional 4-element designs tend to have side-to-center distortions upwards of 5%. The shorter the TR the bigger the distortion. In this, the simpler 4-element designs are similar in distortion metrics to prism lenses. Both of these types of designs go back to the 1920s when, during design, every ray had to be traced through them by hand (and log tables). Today, using modern software, you can trace 10,000 rays a second, automatically, so you can be a little bit more adventurous with a design, making it more complex.

Simpler designs are more suited to larger TRs (3.0+), where they perform OK. Most (not all though) commercial cinemas have these long TRs, so the limitations of the simpler designs aren't apparent until you use them with the short TRs typical of Home Theater.

Additionally, the more surfaces you have available for curving the more you can "condition" or "massage" the beam as it passes through the lens. Take a simple convex lens. You can use it as a projector lens - it inverts and focuses at a distant point - but you'll have astigmatism, color aberration, possible coma and so on. So you add elements (extra surfaces) that get rid of these aberrations. If you look at a projector lens it contains many such elements, each one gradually adding its own little piece of quality to the overall image, making sure the beam isn't too "bent" in any one place along the light path.

Now consider an anamorphic design. If designed as an add-on adapter, especially in Home Theater usage, the diameters of the lenses have to be huge. This makes them very heavy and very expensive to fabricate to exacting standards. So you can't use too many or else you might end up with a great image at a prohibitive cost to the customer. There has to be a compromise position somewhere. Add some surfaces, but not so many that the design prices itself out of the market.

Benefits of added surfaces are that you can tweak the image to be better over a wider range of applications.

For example, a 4-element design that has only 4 outer (glass-air) surfaces (two per individual element in the lens) might have a couple of them flat (plano) to aid in manufacture and assembly. But this leaves only two surfaces that can be curved, necesitating extra-steep curvature on those remaining available surfaces to achieve the desired anamorphic effect.

By contrast, if all four surfaces were curved then the light wouldn't have to be bent as much on each curved surface as it passes through the lens. Having more curved surfaces allows each of them to "share the load" of conditioning the beam. Reducing the number of curved surfaces in a lens (consequently "crowding" the light-bending potential of the lens into less surfaces) makes it more susceptible to aberrations at the margins. It requires more exact placement of the lens in the light path, down to a millimetre or so. Outside these boundaries, lens performance can suffer at the edges.

Lenses with reduced numbers of curved surfaces tend to work well only within a more limited throw range, and throw ratio range. For example, they might be superbly sharp and contrasty at TRs of 2 and up, at throws of 4 to 8 metres, but outside that envelope they tend to lose performance edge. To work outside the envelope you require a new design, optimized for that new envelope.

Now, a design with more surfaces can still use a couple of plano surfaces for ease of manufacture, but can also have a significant number of curved surfaces to do the optical work, simply because there is a greater degree of freedom in the design, due to the extra surfaces. With more surfaces, the designer (and the customer) can have his cake and eat it too.

For example, a 6-element design with two plano surfaces still has 4 surfaces that can be curved. It can have the manufacturing flexibility of plano surfaces, and the optical flexibility of the remaining surfaces being eligible to be curved.

Other advantages of lenses with lots of curved surfaces could be in areas such as ghost imaging. "Ghost" images are the result of reflective interactions of the anamorphic adapter both with the projector lens and with its own internal elements. AR coating is important. There are cheap single AR coatings and more expnsive "multi-coatings". These serve to reduce internal reflection and increase transmission, paying off in brightness and contrast performance. Occasionally, despite AR coating, reflections will conspire to present a focused (or somewhat focused) "ghost" image right onto the screen, particularly during end credits and dark scenes with bright highlights, where contrast is usally at its highest (white characters, fires, flames, torchlights, city lights etc. on a black background). Intuitively you might think that the more surfaces in the lens the more potential for stray reflections, but this is not necessarilty the case. If the designer is careful, by using more curved surfaces he can reduce the chance of ghost images by interfering with the reflection potential inside the lens, presenting too many surfaces for a patent image to escape and form on the screen, making the chances of ghosts actually less than with simpler designs.

In summary, it's simple: the more surfaces you have, given a decent design, the more you can do good things with the light that passes through them.

P.S. This other news lens is not called "Horizon" and bears only a faint similarity to that design.
post #38 of 623
Thread Starter 
Wrongly put. Using a lens should "theoretically" be 33% brighter than zooming

Noted and corrected. Bad habit. I assume everyone can read my mind an knew I was comparing to zooming.
post #39 of 623
Thread Starter 
Does this lens have correction for focus in relation to T.R.? 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?
post #40 of 623
Quote:
Originally Posted by Aussie Bob View Post


I understand that at least one these two new lenses will be a lightweight, low-distortion, 5-element design, arranged in 3 groups, which is a much-needed improvement on the traditional Schenider/Isco (and other) 4-element, 2-group designs.

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

From what I have learned from both your posts and my own R&D is that the current crop of 4E cylindrical lenses have been more or less offered with 'oh it's good enough' attitude. Even when knowing the design is not as good as it could be, yet they have continued to charge insane prices for something that is really a flawed design. Plus the fact that it's design has been around since the 1920's or thereabouts and nobody has been eager enough to make the changes required to improve it's design.

5 elements is certainly a step up in performance from what I understand.

Is that a fair statement?
post #41 of 623
Quote:
Originally Posted by coolrda View Post

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.

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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?
post #42 of 623
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.

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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.

Quote:


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

Probably so. Fair statement.
post #43 of 623
Thread Starter 
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?
post #44 of 623
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".

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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
post #45 of 623
Quote:
Originally Posted by Aussie Bob View Post

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.
post #46 of 623
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?
post #47 of 623
I'm interested to see what the AVS group is coming out with also. The more people that get into CIH the better I say.
post #48 of 623
Thread Starter 
Quote:
Originally Posted by Aussie Bob View Post

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.
post #49 of 623
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.
post #50 of 623
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.
post #51 of 623
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...
post #52 of 623
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.
post #53 of 623
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.
post #54 of 623
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
post #55 of 623
Thread Starter 
Quote:
Originally Posted by GetGray View Post

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?
post #56 of 623
Quote:
Originally Posted by Aussie Bob View Post

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 View Post

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.
post #57 of 623
Quote:
Originally Posted by Aussie Bob View Post

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?
post #58 of 623
Quote:
Originally Posted by Lawguy View Post

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?
post #59 of 623
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).
post #60 of 623
Quote:
Originally Posted by DLopatin View Post

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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