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post #91 of 145 Old 07-24-2009, 09:10 PM
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Definitley will be getting the upgrade lens.

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post #92 of 145 Old 07-24-2009, 09:22 PM
 
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Again my ignorance what is astigmatism and what does it look like?

That's OK. We're all ignorant at first. Then we ask. Then someone shows us. And then we're not ignorant anymore.



Astigmatism
The three images above depict astigmatism: in this case, a differential focus between horizontal and vertical lines. Basically the focal point of the prisms is different to that of the projector lens. Hence you only achieve perfect focus in either vertical or horizontal, but never both.

First, focus the projector on the screen. Place the prism anamorphic in front of the projection lens. Looking at the illustrations (a 4x4x1 pixel checkerboard pattern).

LEFT: The projector lens is focused. When you interpose the prism lens in front of the projector the vertical direction remains focused (as the prisms have no optical power in this direction), but the prisms throw the horizontal direction OUT of focus.

MIDDLE: Leaving the prisms in place, start throwing the projector out of focus significantly. Stop when the checkerboard pattern looks like image #2 (middle). You have been forced to adjust the projector focus because the prisms, by definition, have no adjustment capability. The image in the vertical direction becomes blurred, but the prisms are now projecting clean edges in the horizontal. The projector's out of focus position at this point is, however, perfect for the prisms.

RIGHT Half-way in-between, a "compromise focus". Neither prisms nor projector are in perfect focus, but half-way in between for each. When you move the prism lens out of the way the projector will remain unfocused, because to achieve this "compromise" you have to throw it out of focus to accommodate the optics of the prisms.

A system that, depending on whether you're looking at horizontal or vertical lines, has two (or more) different perfect focus points is said to exhibit "astigmatism".

Prisms, by their nature exhibit astigmatism. No matter how well made, or finely ground, no matter how perfectly flat their faces are, every prism system exhibits astigmatism. This is why the changeover was made early to cylindrical lenses: there are simply more degrees of design freedom with cylindricals than there are with prisms.

You can add a single corrector lens (a weak cylindrical) to a prism system and remove the astigmatism at one, and only one focus point. You can also introduce a more complex corrector that is continuously adjustable, so that for any distance the system will be in focus ( after manual adjustment of the correctors, of course). Such a corrector consists of two or more cylindricals in line with the prisms, which begs the question: why mix multiple cylindricals in this manner with prisms? The device would be heavy, expensive and complex optically. This is why the move was made to pure cylindricals back in the 1950s. They are lighter, have more freedom in design, can accomplish both continuous focus, continuous atigmatism correction and color correction at the same time, and are smaller for just about any given anamorphic task.

Non-uniform sharpness edge to egde
There is another out-of-focus condition where the edges are blurred but the middle of the picture is sharp (or vice versa). Prisms (and cylindrical systems) also exhibit this kind of aberration. With cylindricals it can be effectively compensated for. It is harder to do this with prisms, because they have fewer degrees of freedom in their design. This is not astigmatism, but a separate problem.

Color Aberration
Thirdly, color aberration can mimic blurriness. If vertical lines are not separated enough to be clearly out of color alignment, they can still be separated enough to look, or mimic blurred. You end up with thicker vertical lines (worse vertical focus) no matter how well made the prism system is. The illustrations above exhibit color aberration (they are a worst case for prisms). Combining two or more types of glasses per prisms (cemented doublets) can fix this, but will not affect astigmatism or edge to edge sharpness.

Uncorrected prism systems exhibit all three of the above sharpness-inhibiting aberrations. Together they reduce sharpness of the image by a substantial amount, easily 50%. Your high definition projector's resolution is not fully taken advantage of in these cases.

Geometric Distortion
None of the above will fix geometric distortion which can be defined as equal sized grid squares on the imaging chip being projected at progressively bigger sizes as they reach the edge of the screen. The usual 1:1 point (perfect square grid reproduction) for grid squares in this arrangement is about half way between center and edge of screen. Towards the middle the grid squares are too skinny. Towards the edges they are too fat.
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post #93 of 145 Old 07-24-2009, 10:08 PM
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Thank you Aussie bob for that great explanation.

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post #94 of 145 Old 07-25-2009, 12:25 AM
 
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Originally Posted by Aussie Bob View Post

Not actually. The corrector lenses remove astigmatism only. Astigmatism manifests as differential focus between vertical and horizontal planes and is endemic to any prism design, no matter how "high quality", unless corrected.

Even with a corrector, grid distortion is completely unchanged. To fix it requires heavy investment in very complex and quite strong (bent radically) cylindrical optics, which prism systems (being two plane-sided prisms and a very weak cylindrical corrector) cannot possibly achieve. To be fair, most cylindrical anamorphics do not address this problem all that well either.

Also it should be remembered that correctors only correct precisely for one focal distance. Outside this "sweet spot" they begin to blur away again. To correct for all focal distances you need, once again, cylindrical optics with one section of them (comprising at least two separate lenses) being an adjustable (i.e. moveable) focusing component (i.e. slides back and forth).

Sorry Bob, I did actually mean astigmatism.. I had grid distortion on my mind for some reason. Excellent explanation though!
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post #95 of 145 Old 07-25-2009, 10:04 AM
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Aussie Bob, you certainly are thorough. Good post!
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post #96 of 145 Old 07-25-2009, 12:34 PM
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Quote:
Originally Posted by Aussie Bob View Post

That's OK. We're all ignorant at first. Then we ask. Then someone shows us. And then we're not ignorant anymore.



Astigmatism
The three images above depict astigmatism: in this case, a differential focus between horizontal and vertical lines. Basically the focal point of the prisms is different to that of the projector lens. Hence you only achieve perfect focus in either vertical or horizontal, but never both.

First, focus the projector on the screen. Place the prism anamorphic in front of the projection lens. Looking at the illustrations (a 4x4x1 pixel checkerboard pattern).

LEFT: The projector lens is focused. When you interpose the prism lens in front of the projector the vertical direction remains focused (as the prisms have no optical power in this direction), but the prisms throw the horizontal direction OUT of focus.

MIDDLE: Leaving the prisms in place, start throwing the projector out of focus significantly. Stop when the checkerboard pattern looks like image #2 (middle). You have been forced to adjust the projector focus because the prisms, by definition, have no adjustment capability. The image in the vertical direction becomes blurred, but the prisms are now projecting clean edges in the horizontal. The projector's out of focus position at this point is perfect for the prisms.

RIGHT Half-way in-between, a "compromise focus". Neither prisms nor projector are in perfect focus, but half-way in between for each. When you move the prism lens out of the way the projector will remain unfocused, because to achieve this "compromise" you have to throw it out of focus to accommodate the optics of the prisms.

A system that, depending on whether you're looking at horizontal or vertical lines, has two (or more) different perfect focus points is said to exhibit "astigmatism".

Prisms, by their nature exhibit astigmatism. No matter how well made, or finely ground, no matter how perfectly flat their faces are, every prism system exhibits astigmatism. This is why the changeover was made early to cylindrical lenses: there are simply more degrees of design freedom with cylindricals than there are with prisms.

You can add a single corrector lens (a weak cylindrical) to a prism system and remove the astigmatism at one, and only one focus point. You can also introduce a more complex corrector that is continuously adjustable, so that for any distance the system will be in focus ( after manual adjustment of the correctors, of course). Such a corrector consists of two or more cylindricals in line with the prisms, which begs the question: why mix multiple cylindricals in this manner with prisms? The device would be heavy, expensive and complex optically. This is why the move was made to pure cylindricals back in the 1950s. They are lighter, have more freedom in design, can accomplish both continuous focus, continuous atigmatism correction and color correction at the same time, and are smaller for just about any given anamorphic task.

Non-uniform sharpness edge to egde
There is another out-of-focus condition where the edges are blurred but the middle of the picture is sharp (or vice versa). Prisms (and cylindrical systems) also exhibit this kind of aberration. With cylindricals it can be effectively compensated for. It is harder to do this with prisms, because they have fewer degrees of freedom in their design. This is not astigmatism, but a separate problem.

Color Aberration
Thirdly, color aberration can mimic blurriness. If vertical lines are not separated enough to be clearly out of color alignment, they can still be separated enough to look, or mimic blurred. You end up with thicker vertical lines (worse vertical focus) no matter how well made the prism system is. The illustrations above exhibit color aberration (they are a worst case for prisms). Combining two or more types of glasses per prisms (cemented doublets) can fix this, but will not affect astigmatism or edge to edge sharpness.

Uncorrected prism systems exhibit all three of the above sharpness-inhibiting aberrations. Together they reduce sharpness of the image by a substantial amount, easily 50%. Your high definition projector's resolution is not fully taken advantage of in these cases.

Geometric Distortion
None of the above will fix geometric distortion which can be defined as equal sized grid squares on the imaging chip being projected at progressively bigger sizes as they reach the edge of the screen. The usual 1:1 point (perfect square grid reproduction) for grid squares in this arrangement is about half way between center and edge of screen. Towards the middle the grid squares are too skinny. Towards the edges they are too fat.

Nice explanation but in the Panamorph 480, they have curved surfaces to correct the Astigmatism and I have seen no degradation of resolution at all in my system. Also the prism is placed in a converging F40 cone so the amount of aberrations introduced is small and easily corrected.

Color aberrations are easily corrected because each prism can be made of two prisms. geometric distortion is impossible to correct without introducing astigmatism or a curved screen but that is also true for cylindrical systems.

Cylindrical lenses are harder to make , harder to tolerance and do not offer any performance value over properly corrected cylindrical systems.
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post #97 of 145 Old 07-25-2009, 03:09 PM
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Quote:
Originally Posted by mlang46 View Post

Cylindrical lenses are harder to make , harder to tolerance and do not offer any performance value over properly corrected cylindrical systems.

What ?

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post #98 of 145 Old 07-25-2009, 04:48 PM
 
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Nice explanation but in the Panamorph 480, they have curved surfaces to correct the Astigmatism and I have seen no degradation of resolution at all in my system. Also the prism is placed in a converging F40 cone so the amount of aberrations introduced is small and easily corrected.

The converging cone has little to do with aberration correction, except to limit stray light. In any case, cylindricals are built on this basis too.

A single (or even two) built-in curved surfaces cannot possibly account for all focus positions. As soon as curved surfaces are introduced, you are introducing tilt to the system and a fixed "sweet-spot" focal distance.

I'm not arguing with you particularly, but I'm curious to know why then Panamorph use an additional corrector lens if curved surfaces solve the problem?

Quote:


Color aberrations are easily corrected because each prism can be made of two prisms. geometric distortion is impossible to correct without introducing astigmatism or a curved screen but that is also true for cylindrical systems.

Which is exactly what I conceded above (without specifically mentioning the cylindrical screen solution... but this causes other problems when the lens is removed). As a side note, it is possible to fully correct for geometric and even pincushion distortion with a cylindrical, but it is very difficult and expensive and would have a narrow operating range. However, these aberrations can be amerliorated with a careful design and choice of the combination of lens shapes used.

Quote:


Cylindrical lenses are harder to make , harder to tolerance and do not offer any performance value over properly corrected (prism) systems.

This involces an indirect contradiction to your first statement. If the prism system is a hybrid, using a curved surface (or surfaces) directly on their prisms (as you report) then this is actually a partial cylindrical system which, according to you, is "harder to tolerance and does not offer any performance value over" prism systems. It proves my point: cylindrical surfaces actually must offer a performance dividend if even prism manufacturers use them as part of their design.

In any case, cylindricals are not hard to tolerance at all. You just specify the tolerances and the (usually Chinese) optics company builds them to those tolerances. Tolerancing is taken care of in the design stage, where various scenarios are sampled and tested (in software).

Another advantage of cylindrical systems is that the outer two surfaces act as seals to keep dust out of the inside elements. To similarly seal a prism system you have to add two glass plates (admittedly one of them may be a corrector lens), one at either end. This adds four surfaces to the system with the consequent loss of at least 2% in light transmission if the surfaces are coated (and therefore expensive), and more loss, plus potential ghost imaging if they are not coated.

Cylindricals are generally much lighter than prism systems and are continuously adjustable (or should be if designed properly). It's preposterous to claim that a cylindrical system which offers as many curved surfaces - in any combination of radii, shapes and thicknesses - as there are surfaces in the system has no more degrees of freedom in design, hence performance value, than two prisms which involve only plane surfaces and a couple of angles (maximum 5 for a CA corrected system) between them.

Anecdotally, if prism systems are so good why don't the lensmakers (Hawke, Panavision, Isco, Schneider etc.) utilise prism systems? I admit this is not a rigorous mode of argument (i.e. referring to "the experts"... experts have been wrong before now) but why did Panavision abandon prisms by the late 1950s? I suppose it could be an international conspiracy to keep the truth from the public, rip-off CIH consumers and fool the slow thinkers out there into paying through the nose for something that doesn't offer any advantage. Or, then again, it might be because these companies think that, overall, cylindricals actually do offer performance and convenience dividends.
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post #99 of 145 Old 07-25-2009, 08:46 PM
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Quote:
Originally Posted by Aussie Bob View Post

That's OK. We're all ignorant at first. Then we ask. Then someone shows us. And then we're not ignorant anymore.



Astigmatism
The three images above depict astigmatism: in this case, a differential focus between horizontal and vertical lines. Basically the focal point of the prisms is different to that of the projector lens. Hence you only achieve perfect focus in either vertical or horizontal, but never both.

First, focus the projector on the screen. Place the prism anamorphic in front of the projection lens. Looking at the illustrations (a 4x4x1 pixel checkerboard pattern).

LEFT: The projector lens is focused. When you interpose the prism lens in front of the projector the vertical direction remains focused (as the prisms have no optical power in this direction), but the prisms throw the horizontal direction OUT of focus.

MIDDLE: Leaving the prisms in place, start throwing the projector out of focus significantly. Stop when the checkerboard pattern looks like image #2 (middle). You have been forced to adjust the projector focus because the prisms, by definition, have no adjustment capability. The image in the vertical direction becomes blurred, but the prisms are now projecting clean edges in the horizontal. The projector's out of focus position at this point is, however, perfect for the prisms.

RIGHT Half-way in-between, a "compromise focus". Neither prisms nor projector are in perfect focus, but half-way in between for each. When you move the prism lens out of the way the projector will remain unfocused, because to achieve this "compromise" you have to throw it out of focus to accommodate the optics of the prisms.

A system that, depending on whether you're looking at horizontal or vertical lines, has two (or more) different perfect focus points is said to exhibit "astigmatism".

Prisms, by their nature exhibit astigmatism. No matter how well made, or finely ground, no matter how perfectly flat their faces are, every prism system exhibits astigmatism. This is why the changeover was made early to cylindrical lenses: there are simply more degrees of design freedom with cylindricals than there are with prisms.

You can add a single corrector lens (a weak cylindrical) to a prism system and remove the astigmatism at one, and only one focus point. You can also introduce a more complex corrector that is continuously adjustable, so that for any distance the system will be in focus ( after manual adjustment of the correctors, of course). Such a corrector consists of two or more cylindricals in line with the prisms, which begs the question: why mix multiple cylindricals in this manner with prisms? The device would be heavy, expensive and complex optically. This is why the move was made to pure cylindricals back in the 1950s. They are lighter, have more freedom in design, can accomplish both continuous focus, continuous atigmatism correction and color correction at the same time, and are smaller for just about any given anamorphic task.

Non-uniform sharpness edge to egde
There is another out-of-focus condition where the edges are blurred but the middle of the picture is sharp (or vice versa). Prisms (and cylindrical systems) also exhibit this kind of aberration. With cylindricals it can be effectively compensated for. It is harder to do this with prisms, because they have fewer degrees of freedom in their design. This is not astigmatism, but a separate problem.

Color Aberration
Thirdly, color aberration can mimic blurriness. If vertical lines are not separated enough to be clearly out of color alignment, they can still be separated enough to look, or mimic blurred. You end up with thicker vertical lines (worse vertical focus) no matter how well made the prism system is. The illustrations above exhibit color aberration (they are a worst case for prisms). Combining two or more types of glasses per prisms (cemented doublets) can fix this, but will not affect astigmatism or edge to edge sharpness.

Uncorrected prism systems exhibit all three of the above sharpness-inhibiting aberrations. Together they reduce sharpness of the image by a substantial amount, easily 50%. Your high definition projector's resolution is not fully taken advantage of in these cases.

Geometric Distortion
None of the above will fix geometric distortion which can be defined as equal sized grid squares on the imaging chip being projected at progressively bigger sizes as they reach the edge of the screen. The usual 1:1 point (perfect square grid reproduction) for grid squares in this arrangement is about half way between center and edge of screen. Towards the middle the grid squares are too skinny. Towards the edges they are too fat.

This should be a sticky. Im sure there would be many members(especially venturing into the anamorphic) in the near future that would ask the same question. just a thought.

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post #100 of 145 Old 07-26-2009, 01:02 PM
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Quote:
Originally Posted by Aussie Bob View Post

The converging cone has little to do with aberration correction, except to limit stray light. In any case, cylindricals are built on this basis too.

A single (or even two) built-in curved surfaces cannot possibly account for all focus positions. As soon as curved surfaces are introduced, you are introducing tilt to the system and a fixed "sweet-spot" focal distance.

I'm not arguing with you particularly, but I'm curious to know why then Panamorph use an additional corrector lens if curved surfaces solve the problem?



Which is exactly what I conceded above (without specifically mentioning the cylindrical screen solution... but this causes other problems when the lens is removed). As a side note, it is possible to fully correct for geometric and even pincushion distortion with a cylindrical, but it is very difficult and expensive and would have a narrow operating range. However, these aberrations can be amerliorated with a careful design and choice of the combination of lens shapes used.






This involces an indirect contradiction to your first statement. If the prism system is a hybrid, using a curved surface (or surfaces) directly on their prisms (as you report) then this is actually a partial cylindrical system which, according to you, is "harder to tolerance and does not offer any performance value over" prism systems. It proves my point: cylindrical surfaces actually must offer a performance dividend if even prism manufacturers use them as part of their design.

In any case, cylindricals are not hard to tolerance at all. You just specify the tolerances and the (usually Chinese) optics company builds them to those tolerances. Tolerancing is taken care of in the design stage, where various scenarios are sampled and tested (in software).

Another advantage of cylindrical systems is that the outer two surfaces act as seals to keep dust out of the inside elements. To similarly seal a prism system you have to add two glass plates (admittedly one of them may be a corrector lens), one at either end. This adds four surfaces to the system with the consequent loss of at least 2% in light transmission if the surfaces are coated (and therefore expensive), and more loss, plus potential ghost imaging if they are not coated.

Cylindricals are generally much lighter than prism systems and are continuously adjustable (or should be if designed properly). It's preposterous to claim that a cylindrical system which offers as many curved surfaces - in any combination of radii, shapes and thicknesses - as there are surfaces in the system has no more degrees of freedom in design, hence performance value, than two prisms which involve only plane surfaces and a couple of angles (maximum 5 for a CA corrected system) between them.

Anecdotally, if prism systems are so good why don't the lensmakers (Hawke, Panavision, Isco, Schneider etc.) utilise prism systems? I admit this is not a rigorous mode of argument (i.e. referring to "the experts"... experts have been wrong before now) but why did Panavision abandon prisms by the late 1950s? I suppose it could be an international conspiracy to keep the truth from the public, rip-off CIH consumers and fool the slow thinkers out there into paying through the nose for something that doesn't offer any advantage. Or, then again, it might be because these companies think that, overall, cylindricals actually do offer performance and convenience dividends.

Actually the converging cone has everything to do with aberration correction because aberrations 3rd 5th and 7th go as the inverse of the Fnumber. Aberrations are either reduced or induced depending on how steep the incident ray angles hit the surface which is why you have very little monochromatic Siedel aberrations, when you put a anamorphic prism in front of a converging beam with an extremely high Fnumber. even so there is a small amount of astigmatism generated by a converging beam trans versing a glass plate and this can easily be taken out by attaching a very thin molded element to one of the prism surfaces or better yet diamond turning the the surfaces than you just program the corrector into one of the prism surfaces.

cylinders are lighter so that's one advantage but optically they have no advantage over the Panamorphic system with an astigmatic corrector. I have designed both types of system for military and commercial interests and optimized and analyzed both systems using two different Optical design programs Zemax and Code V. Both systems properly designed, properly toleranced and properly manufactured will not degrade the image outside of geometric distortion in any way. Its true you have more degrees of freedom in a cylindrical but because you are putting the anamorphic element in front of a slowly converging beam the amount of astigmatism you generate is small and you really do not need four cylindrical elements or 8 surfaces to get excellent correction. Optical designers will insult another designers lens design by saying that was a lot of glass meaning you could of gotten the same performance with less elements.

The prism system has other advantages. Because the surfaces are flat or near flat with the inclusion of the corrector the anti reflection coating can be designed to be much better and the polishing can be smoother (smaller scratch and dig) thus the scatter introduced and ghost images are much lower in a prism system than in a cylindrical system. Also in a cylindrical system ,not only do you have tip tilt and decenter tolerances ,you also have radius and rotation tolerances. In a prism system all you have for the most part are flatness and angle tolerances. In a prism because of the thickness of the glass you have much tighter bubble tolerances.

But the proof is in the pudding, I personally own a Panamorph 480 and a Sim2 HT380 and when I put the prism system in front of my projector I can detect no change in resolution which, as an optical engineer, does not surprise me. What's really amazing to me is I have seen people place that prism system in front of a JVC RS20 with a 40,000 : 1 contrast ratio and measure the same contrast ratio after they put the prism in front of the projector as they did before. Which means the polish and the antireflection coatings are very very good indeed. I can not do that measurement myself because frankly the on/off contrast ratio on my Sim2 ht380 sucks.

So why would I pay 2 to 3 times as much to replace a prism system with a cylindrical system when the prism system has no detectable effect on the image resolution except expansion and geometrical distortion?

also because your visual acuity is one sixth at the edge of the field as it is at the center in a normal viewing environment , I don't think you would notice the difference even if you did not correct the small amount of astigmatism .as Panamorph does, in a well designed prism system. Most optical designers ,knowing how the human's eye works sacrifice resolution at the edge of the field to get better resolution at the center.

as far as the sweet spot as you call it , the depth of focus in an F40 screen is so large that the sweet spot is all over the screen. take a piece of paper and move ti in and out of the screen and look at how the focus changes. I will bet you can move it 6 inches before you even notice a focus change.

I don't know why Panavision abandoned prism but it was probably do to size because those prisms in front of a commercial projector would really be heavy.

As to why people pay more. Well there is a sucker born every minute and if you want to meet some, go to the + 20,000 forum
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post #101 of 145 Old 07-26-2009, 04:34 PM
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This has turned out quite interesting

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post #102 of 145 Old 07-26-2009, 10:09 PM - Thread Starter
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Originally Posted by CRGINC View Post

I believe there is some pinchusion distortion on the sides but not nearly as much as top and bottom. I have a small amount in my setup. It is about equal on both sides.

Charles

Charles,

May I ask what do you have? Did you install it yourself?
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post #103 of 145 Old 07-26-2009, 10:59 PM
 
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The 'depth' of pincushion will be less on the sides because the sides are shorter.. It would be like taking a short length of the top or bottom of the screen.. ie, there will appear to be less pincushion... but it's all relative I believe (Bob?) The short sides are 42% of the top and bottom lengths so overall, the dip or pincushion should be 42% of the top or bottom amount.... I could be wrong, someone like Aussiebob should be able to verify.. I was just thinking logically, doesn't always work in optics though.

Alignment of the projector to the screen and lens to projector, to the enth degree mind you, plays a big part in this also.
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post #104 of 145 Old 07-27-2009, 01:13 AM
 
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cylinders are lighter so that's one advantage but optically they have no advantage over the Panamorphic system with an astigmatic corrector...

I was going to quote more but this will do. Just a few random thoughts...

The main advantages of cylinder lenses over prisms are their ability to continuously adjust astigmatism, their relative lightness and degrees of freedom in design, the latter of which allows at least partial correction of some of the defects that are part and parcel of prisms systems (corrected or uncorrected) like geometric distortion.

A thoughtful cylinder design will reduce geometric distortion which prisms can never do without complex extra elements (which will be cylindrical, which renders prisms pointless anyway).

Much of your tolerancing objections to cylinder systems apply equally to prisms, especially tilt and rotation (which is just Z-axis tilt I guess). So let's not get too excited about this.

Quote:


"... better yet diamond turning the the surfaces than you just program the corrector into one of the prism surfaces."

Oh please... "diamond turning" is easy to say but very expensive, and once you add a curved surface to the prism you are introducing potential tilt tolerances as well as making the system cylindrical, or at least hybrid cylindrical. Why not just make the whole thing cylindrical and be done with it?

Don't want to get into an esoteric flame war type of thing here (7th order aberrations are definitely esoteric) but you're underrating the astigmatism performance (or rather, lack of performance) of pure prisms. It's very noticeable and quite annoying without correction (as my illustration above seeks to demonstrate). If the pixels in the illustration were twice the size (i.e. if the projector was 960x360) you could see those pixels relatively clearly, but at true high definition you can't with uncorrected prisms. The illustration is modelled (not a direct photograph), but my observations of an actual system that the model was based on (where the incident planes of each prism were perpendicular to the axis of the beam) confirm it. And this is from ten feet away, not three inches from the screen. Raw prism astigmatism stands out like dog cojones. Which brings me back to the continuous adjustment concept that really only cylindricals offer. With continuous adjustment you get the very best at any projection distance, not just at the sweet spot.

I agree that there are a lot of mugs out there who pay too much for only incremental performance improvement. I've read the +$20k threads too. By the same token, that doesn't mean everything that's expensive is automatically a rip-off (although I'm on record as saying I believe Iscos are too much for what they do).

I guess we could argue forever over this. I'm happy you're happy. Shall we leave it at that?

Re. Pincushion at the sides
Yes there is some, but it's way lower in proportion than 27/64ths of the pincushion at the top, actually about 1/4. This is because there's no optical power in the vertical direction. The pincushion down the sides is residual, and can be discounted as negligable (say less than 0.25% at a throw ratio of about 2.0).
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post #105 of 145 Old 07-27-2009, 06:07 AM
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(although I'm on record as saying I believe Iscos are too much for what they do).

Especially for what they retail here in Australia, 18KAU ridiculous.

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post #106 of 145 Old 07-27-2009, 06:25 AM
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Frank,

if i visit australia one time, i can bring you one lens with me
Actually, an ISCO 3 costs here in germany around 5500€.
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post #107 of 145 Old 07-27-2009, 06:34 AM
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Frank,

if i visit australia one time, i can bring you one lens with me
Actually, an ISCO 3 costs here in germany around 5500.

At that price you will have some happy people here in Australia.

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post #108 of 145 Old 07-27-2009, 06:55 AM
 
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Especially for what they retail here in Australia, 18KAU ridiculous.

Where did you get that price from? I heard it too, but I'm wondering whether it's a rumour.

5500 EUROs in Germany works out to AUS$9,400 at today's exchange rate. Add 10% GST, plus freight and there's not much change from AUS$11,000. Throw in a stand and you're around A$14,000.
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post #109 of 145 Old 07-27-2009, 06:59 AM
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Where did you get that price from? I heard it too, but I'm wondering whether it's a rumour.

Surround Sounds Perth!! I gasped when I heard that! And the Panamorph UH480 $8000AU - $11000AU depending who is more greedier.

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post #110 of 145 Old 07-27-2009, 07:09 AM
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Wow. Things are expensive down there...
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post #111 of 145 Old 07-27-2009, 07:14 AM
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Wow. Things are expensive down there...

Its quite ridiculous to be honest.

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post #112 of 145 Old 07-27-2009, 07:42 AM
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Its quite ridiculous to be honest.

I agree the pricing you have quoted a few times does seem overly high. Did you check with my Isco distributor in AU? He's in Taren Point. Don't know my way around that continent so maybe he's too far.

Or check with AVS here first? If you can't find a dealer in or that ships to AU at "normal" pricing, contact me off-line. The pricing mentioned above in Euros most likely includes the Multistand II (or it should).
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post #113 of 145 Old 07-27-2009, 07:59 AM - Thread Starter
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Wow it is very expensive over there...

At the end of the day, regardless how the a-lens is superb and expensive, we have to have a good PJ/source. Unless the a-lens will magically make the better picture even better, right? Sorry it is just me, I can't see spending a lens for $10K+ for that 15% to 20% unless money is no object.
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post #114 of 145 Old 07-27-2009, 08:58 AM
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It all depends on the other parts. I always tell people to compliment their system. If you have a $100k projector, getting a top end anamorphic lens is a no brainer. But when your lens is just as much (or more) as your projector, well, doesn't make much sense...
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It all depends on the other parts. I always tell people to compliment their system. If you have a $100k projector, getting a top end anamorphic lens is a no brainer. But when your lens is just as much (or more) as your projector, well, doesn't make much sense...

Agree Jason. But the problem now is most of the lens, MKIII, 480 and 5000, we covered here are $3K range, the Panny 3K is less then that, what lens would you recommend your customers with Panny 3K these days?
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post #116 of 145 Old 07-27-2009, 09:34 AM
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Well I should say there is a bottom end, and right now the $2000-$3000 edge is really it. As mentioned before, if that is too much you are probably better doing the zoom method (the cheap lens are just going to hinder performance more than anything).
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Well I should say there is a bottom end, and right now the $2000-$3000 edge is really it. As mentioned before, if that is too much you are probably better doing the zoom method (the cheap lens are just going to hinder performance more than anything).

Thanks for your advice Jason.
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post #118 of 145 Old 07-27-2009, 11:26 AM
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Well I should say there is a bottom end, and right now the $2000-$3000 edge is really it. As mentioned before, if that is too much you are probably better doing the zoom method (the cheap lens are just going to hinder performance more than anything).

I struggled with this myself. I paid 3k even, for a RS10 and had budgeted up to 2k for a Prismasonic A lens or used 480 or something. After installing the rs10 on a 116" wide scopeish screen I was still very happy with the iq at that size compared to smaller 16x9 content. Can't see a real difference? Maybe I am missing out on something? How do you know if you cannot test what an A lens will do for your set up? The more I was happy with my scope content the more I wondered if it made sense to have a $2k lense with a $3k pj? I know some of that is human nature talking myself into not spending the money but I am looking for definite improvement in PQ. I do not need brightness improvement since I have a high power screen, the pj is shelf mounted and easy to zoom so convenience is not an issue. What I really want to see is a sharper pic but I wonder if my $2k investment would have a better return on investment if I just upgraded the pj - or would the lense make the difference?

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post #119 of 145 Old 07-27-2009, 12:51 PM
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Thanks for your advice Jason.

Always happy to help.
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post #120 of 145 Old 07-27-2009, 12:52 PM
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I struggled with this myself. I paid 3k even, for a RS10 and had budgeted up to 2k for a Prismasonic A lens or used 480 or something. After installing the rs10 on a 116" wide scopeish screen I was still very happy with the iq at that size compared to smaller 16x9 content. Can't see a real difference? Maybe I am missing out on something? How do you know if you cannot test what an A lens will do for your set up? The more I was happy with my scope content the more I wondered if it made sense to have a $2k lense with a $3k pj? I know some of that is human nature talking myself into not spending the money but I am looking for definite improvement in PQ. I do not need brightness improvement since I have a high power screen, the pj is shelf mounted and easy to zoom so convenience is not an issue. What I really want to see is a sharper pic but I wonder if my $2k investment would have a better return on investment if I just upgraded the pj - or would the lense make the difference?

I think you answered your own question...you said you were "still very happy". Why test fate (and your wallet)?
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