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Discussion Starter · #1 ·
Radeon/WinDVD

Star Trek Insurrection

The photo was taken with a 640x480 Mavica


This is about as good as I was able to get the geometry after spending about ten minutes varying the angle of the projector and the Panamorph. I have the projector flat on a table (perpendicular to the screen). The Panamorph is elevated at it's front edge by the thickness of a standard CD case. And I have the keystone adjustment on the projector two clicks from the center position. The front of the Panamorph is 94" from the screen.

Question? Has it been decided yet if throw distance will be a factor in how bad the distortion is?

http://members.home.net/bobwood21/2.JPG


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~ The Sultan of Cheap ~





[This message has been edited by RobertWood (edited 09-05-2001).]
 

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Yikes, kinda looks like a giant old picture tube!


Kelly
 

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Throw distance should not be the issue (once over the 1.65 recommended) but image offset or image shift or any other term used for a image that is not (I think center) edge aligned seems to be what is creating the non linear distortion...


Your appears a little odd as I have not seen this barrel distortion before (or had it mentioned) and its just another thing to worry about... Plus many of us do not have a digital keystone correction nor (I think) would want to use one if we had a nicely scaled source...


I can also (believe) I can still see the non linear compression in the legs but I would want to look at the source image sans lens first... Are you unable to get a the image to look square (without barreling) with just LT150 and Pannie what happens if you took keystone correction off ???


Thanks for putting up with all these Q's...


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HTPC without using windows... GUI Front Ends for Home Theater
 

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ST:I is 2.35:1 right? In that case most of the distortion will be in the black bar below. If we only watched that aspect ratio and greater it wouldn't really be a problem as we could then just shift the video up to the top of the display using a HTPC with YxY or DVDsubber. But if so - the Panamorph2 would have been a better alternative again.


When I think about it if you have a HTPC then Panamorph2 would be a better alternative in the first place anyway. You'd then get the full panel resolution for 2:35:1 and full vertical resolution for 1.78:1 with black bars on the sides, and full resolution for 1.33:1 by sliding the Panamorph2 to the side.


Hopefully Cygnus are working on making sure the Panamorph2 doesn't have the same distortion problem as the current Panamorph.


As for the barrel distortion - it's just the opposite of the pincushion seen with the ISCOII. I'd imagine if you reversed it then there wouldn't be much difference between the two - except the ISCO doesn't have the non-linear compression issue the Panamorph does http://www.avsforum.com/ubb/biggrin.gif


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/frode


[This message has been edited by Frode (edited 09-05-2001).]
 

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Robert, what's your impressoin of the overall image quality? Outside of the distortion is there a significant improvement in the image - should be for the price! If the top and bottom were masked would this make a difference (big)?


Bottom line - will you use this lens with the LT150? If not, then what use is it to 80% of the target market - off axis projector owners?


Thanks,


Grant
 

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Discussion Starter · #7 ·
There is improvement with the increased resolution and brightness. How much improvement is going to be subjective.

Hopefully with more time spent trying to tweak the orientation of the lens to the projector the distortion could be alleviated further from what my photo shows.


I bought this thing to use with my DILA projector. I set it up with that last night and got perfect geometry and a very pleasing picture. Unfortunately I may not be able to use it though. To fill my screen in this short room the DILA has to be at the rear wall and zoomed all the way out.

With the Panamorph in place I'm not able to fill out the screen. So now I'm going to have to make the decision whether to keep it and go to a slightly smaller screen size

or not use it.


Phreddy, Next time I have it set up I'll take the same picture with no keystone adjustment. And another without the lens in place for comparison.


Bob


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[This message has been edited by RobertWood (edited 09-05-2001).]
 

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I don't know the correct terms, but it looks like what should be darks pants legs have white light pollution in them.


Was that the way it appeared on the screen? Maybe this is an artifact of the camera? Hopefully that is not from the panamorph.


Best regards,

Doug
 

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Discussion Starter · #9 ·
Doug,


I hung my Stewart high gain fixed mount to take the picture.

This screen has bad hotspotting and I quit using it on that account. I think that's why you're seeing what you described.


Bob


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[This message has been edited by RobertWood (edited 09-05-2001).]
 

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I have been lurking on this issue and with the panamorph touching down this week I thought I would seek clarification on a few issuses.


Bob,

I was under the impression that when set up correctly, the panamorph would not change the throw distance of the projector. My understanding was that if you could fill the full width of the screen, once you had the lens dialed in you would have the same width image compressed to 75% of the original height with an image drop that may exceed that necessary to bring the top edge of the image to the top edge of your screen. I am specifically referring to your example with the D-ILA projector, as I have no practical experience with the LT150. Did you have to tilt the D-ILA projector at all to achieve good geometry?


One isolated question, what are D-ILA users using as a "Vertical size of light spot at Panamorph" when using the calculator?


Thanks



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Don O
 

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Discussion Starter · #11 ·
False alarm, Don. The Panamorph is not the culprit. I'm not able to fill my current screen with the room length without the Panamorph in place either. I thought my previous and current screens were the same 80" width. But the black borders on the old screen made it a little less wide.

I am really cutting it close in this room. I've been wanting to build a hush box enclosure onto the window frame on the back wall. Now I know I will be doing that. It will eliminate the fan noise and also give me a couple feet more throw.


Bob


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[This message has been edited by RobertWood (edited 09-05-2001).]
 

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Bob,

thanks for the clarification. I have very little room to maneuver. This would be a deal-killer for me.


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Don O
 

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One of the reasons for the severe barrel distortion is the short throw lens of the LT150. The distortion will not be this bad with the MINORITY(cause everyone has a 150) of projectors.


Scott
 

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for the record the shorter the throw the more barrel distortion...likewise with the ISCO 2 the shorter the throw the more pincushioning..the LT150 is one of the shortest throw lenses out there that comes standard on this type of projector....the panamorph as the ISCO has varying performances based on lenses use on the given projector...


Regards,

John
 
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