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Well after years of ZOOMING Ive finally joined the camp and NEVER to return!

Only the guys that take the plunge know and understand why


 

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Discussion Starter · #23 ·
Last night I spent some taking some light readings for comparison. I ran several readings at various bulb settings, iris settings and with and without the lens. Theoretically there should be a 33% gain of light with the lens in compared to using the zoom method. 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.


Over the course of taking these measurement I came up with a couple formulas for figuring light needed for certain size screens. I know that question is asked frequently. The few givens are that your using a 2.35 screen with one of these lenses. I didn't add in for screen loss or gain. These are for 1.0 neutral gain screens but it's easy to figure in for screen loss or gain. These will hopefully make quick work of matching projectors and screens. Target flts(footLamberts) is typically 12-16. You can use 12 as a baseline. That's bright in a light controlled room. These were done in short time so there could be room for improvement. I actually used to be quite handy figuring load calc's as I have a C20/C38. But working for the world's largest telecom for the last eleven years has fried my brain.


To match your projector to a screen:

Lumens/target ftls*3.855= Diag 2.35 screen

Diag size/1.087= 2.35 screen width

Screen width*1.087= 2.35 diag size


To match your screen to a projector:

Screen Diag/3.855*ftls= Lumens


Remember to double lumens on bulb-type projectors to take in to consideration aging loss.
 

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Discussion Starter · #24 ·

Quote:
Originally Posted by RapalloAV /forum/post/18917258


Well after years of ZOOMING Ive finally joined the camp and NEVER to return!

Only the guys that take the plunge know and understand why

Very nice, sweet setup with the Kino-Linear and Mirage surrounds I believe.
 

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Originally Posted by coolrda /forum/post/18918020


Very nice, sweet setup with the Kino-Linear and Mirage surrounds I believe.

Im using a Kino-Torsion with my Schneider Cine-Digitar Anamorphic 1.33x M Lens, and yes they are Mirage surrounds as part of my 7.1.


I use two motorised screens, 16x9 in front is 120" and rolls over the back of the roller.

2.35 Scope screen 140" dia. 3250mm wide and rolls over the front of the roller.


I change ratios and stretch with an iScan Duo which I think is the best thing ever!


 

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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.
 

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Quote:
Originally Posted by coolrda /forum/post/18879688


It's time to start a thread that encompasses all of these type of lenses. Though there have been threads in the past that have been devoted to the Isco 3L or Schneider 1.33 lenses, I think now is the time to start a new expanded thread to include all commercially available Cylindrical Anamorphic Lenses. Hopefully this can be a source of reference to all present and future owner's of these lens.


At the present time these are the lenses available and that make up this group.

Cavx MK4, Isco 3s, Isco 3L, Schneider 1.33X, Schneider 1.33X M, Schneider 1.33X XL. The Isco 3s/Schneider 1.33X M and Isco 3L/Schneider 1.33X XL are identical except for the body.


The current mounts for the Isco lenses are the Tech Ht mounts which include the Cineslide/MultiStand 2 automated lens sled/lens mount system. A Tabletop mount/MultiStand 2 is also available for stationary lens mounting. These work for the Schneider lenses as well. Schneider also has their own lens mount systems available from their dealer network. Currently they have the Kino-Linear slide system, which is being discontinued, and the Kino-Torsion swing system. All of these systems have pitch, yaw and roll adjustments for precise lens alignment. The Cavx Mk4 comes with a stationary mount but should be able to be mounted to a Cineslide or Panamorph sled system.


The advantage of the cylindrical lens is that it works like a traditional camera lens. With the adjustable focus element, you have the ability to have perfect focus from edge to edge, top to bottom, side to side. Artifacts such as Astigmatism and Chromatic Aberration are a non-issue with these type of lenses. Essentially the image enters and leaves untouched with the exception of two things, it's horizontally expanded by 33% and there is a very slight amount of pincushion. Light loss from the lens is small and alleviated by the corresponding gain due to the increased pixel count of 33%.


Unfortunately, these lenses aren't readily available for viewing. Not to many dealers have these or any A-Lens available to demo. Hopefully this will be a place for those contemplating a purchase can go for reference, to ask questions or to be reassured as these lenses are very expensive, though worth every penny, in my opinion.

Great idea.

I think my lense has actually gone UP in value.

A rarity for anything in consumer electronics.


Here is my setup:
Link


JVC RS20 + CineSlide CSII Anamorphic Lens Transport + ISCOIIIL a-lens


w/ install help from funlvr1965


Mike
 

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Quote:
Originally Posted by Alan Gouger /forum/post/18919288


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.

My Crystal Ball says....CAVX
 

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Quote:
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.

Quote:
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.

Quote:
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.

Quote:
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...

Quote:
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.
 

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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.
 

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



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...
 

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Quote:
Originally Posted by CAVX /forum/post/18921969


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
 

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


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 /forum/post/18923064


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.
 

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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.
 

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Discussion Starter · #38 ·
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.
 

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Discussion Starter · #39 ·
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?
 

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



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?
 
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