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Discussion Starter · #1 ·
I just recently purchased the prismasonic H200 (horizontal stretch) lens for my HT1000. Previously, I owned the optimorph lens made for the HT1000 and had no problems with that lens.


With the H200, pincushion/geometric distortion is very minimal so I'm happy in the department..... BUT I'm getting MAJOR color separation at the outer thirds of the image. In effect, it basically looks like a badly converged CRT.


Here's a crosshatch pattern shot:

http://home.comcast.net/~hyunsac/images/crosshatch.jpg


Here's an actual scene. You can see a blue outline on the left side of the image. Much more pronounced if viewed in person:

http://home.comcast.net/~hyunsac/images/blue.jpg


I've tried to adjust the lens position and the dual knobs but CANNOT get rid of this problem. I've contacted prismasonic and they told me that this was expected and can only be seen on test patterns. But I can clearly see the color separation in regular DVD scenes. How can this possibly be acceptable???


So... is this normal for a horizontal stretch lens?? Does this occur on an ISCO lens? What can I try to fix this problem? I've done everything from reposition the lens in line with the PJ and adjusting the knobs. Nothing works. I cannot believe they would sell a lens that causes this horrible of a "misconvergence".
 

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It is chromatic aberration. You may be able to reduce it slightly by mounting the projector further back so the light entry angles are not as wide. You won't be able to get rid of all the aberration.
 

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I use both a Panamorph and ISCO II anamorphic lens with my HT1000. The Panamorph shows slight colour fringing at the top of the image only and this is not visible from a normal seating distance. The ISCO II (which I prefer) shows none at all, although it does distort the image slightly (looks like a curved screen) which can be easily masked (I actually like the curved screen look, so sometimes don't mask it).


The "convergence" problem you are seeing would be unacceptable to me (judging from your picture).


Cheers,


Grant
 

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Discussion Starter · #4 ·
Thanks for the tip Guy. I guess there's not much else I can do. I already have the projector in minimum zoom and the lens right up to the HT1000 to make the entry angles as small as possible. I can deal with slight chromatic aberration, but this lens makes my HT1000 look like a badly converged CRT. The pictures say it all. The thing is, I even talked to prismasonic before purchasing and they told me that I shouldn't have any problems with the HT1000. So I'm very unsatisfied to say the least.


Grant, good to hear you're not having problems with the ISCO II. That at least tells me horizontal stretch lenses with the HT1000 is possible and that the prismasonic is causing the problem here.
 

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Discussion Starter · #6 ·
The problem can't be solved. It's just the nature of the optics and the laws of physics.


Bottom line: The H200 will not work with short throw pj's. You WILL get MAJOR chromatic aberration as you can see in the pics.


I sold my lens to a seleco owner and he's having no issues at all with it since the seleco is a long throw pj.


I would probably not use this lens with a Z2 based from what I have experienced. The Z2 is a short throw pj and may actually be worse than the HT1000 since it's 16:9.
 
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