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Discussion Starter · #1 ·
As it has come to light that Davis owners are going to have to live with some distortion if they want to use a Panamorph it seems logical to find out if this is applicable to all projectors that do not shoot 'edge aligned' and how much of the projector population may or may not be affected.

Before too many people get too worried the only projector that has been verified to have a problem is the Davis models... However as the cause of the problem is apparently the off axis projection angle and as this is a common thing it seems logical that it may apply to some, or many, others..


What I am suggesting we do is list the 4:3 projector we have and the amount of image offset (or image shift) using a constant on a 96 inch image width (or a 120 inch diagonal with 4:3).. If the zoom has a range please indicate full range..


What is even more valuable is if you have had the opportunity to test with a Panamorph indicate success or not at achieving a exact 16:9 image without any distortion. If at all possible please use a convergence test image and measure the size of the circles so that this is not nearly right but right or wrong. It should also be irrelevant where the image is positioned in relation to your screen as this would not be a fault of the device itself.


What we believe to know so far...


Davis models - 6 to 14 depending on zoom - definite problem.


DILA all models - edge aligned - many positive reports (please check with measurements)...


LT150 - 10.3 inches - status unconfirmed


LT85 - 14.2 inches - status unconfirmed


Yamaha DPX-1 - 14 3/16 inches - status unconfirmed


I have got the last three from online image calculators or PDF's... Please tell me if I am wrong on these and if anyone wants to make a mission of looking up specs on lots of machines I think the info would be valuable...


What about the Sanyo's and Plus's etc...


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I have no direct experience with the PLV-60 in combination with the Panamorph, but it does have a motorized lens shift so it can project an edge-aligned image.


Regards,


Kam Fung
 

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My take on the problem is that it might be due to the lack of parallelism of the light rays. Thus long throw lens would have less problem. I seem to remember in the early days of the panamorph discussion that shawn said that there was a minimum throw ratio recomended. Anyway I provided both for my LT100.


Lt100 with a 96" wide screen has offsets from top aligned as follows:


Mode Offset Projection distance

Tele mode 14" 250.3"

Wide mode 14" 192.1"


What are the numbers for the davis models?




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Gary


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Discussion Starter · #4 ·
Davis DL450 as mentioned above is only 6 - 14 depending on zoom... As I think many would be happy to remount their PJ then you can assume that even its minimum 6 inches would be a problem...


I suspect that the large beam size + image shift + short throw are all working in unison against the Davis units..


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Man would I love to see some comparable images from different projectors!




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VX1(LT100) 14" drop specified for an 8'x6' screen projection distance 19ft. Claims zoom does not impact - but it gets worse with zoom and I am about midway.


I think this is common with any presentation based projector to allow table top operation.


I have 9' ceilings to get the 4:3 screen top at 8' I have the projector front touching the ceiling with few degrees of tilt.


To get a 16x9 screen aligned 1' from ceiling I would require even more tilt. Sounds like I would have major compression distortion with the panamorph.
 

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Discussion Starter · #7 ·
Quote:
I think this is common with any presentation based projector to allow table top operation.
This is exactly why I cant believe this has not come up already and why I am trying to convince myself that it must be the Davis that is especially bad and others will be only marginally distorted...


Wasn't it supposed to be a distortion free image to improve on the cost and drawbacks of the ISCO ???


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Sanyo PLC-XP21N 3.5 inches



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John
 

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From Shawn's other post it sounds related to the angle that the light is traveling through the pannie. Thus for short throw projectors with 14" drop the light would be coming through at a steeper angle then a long throw projector with the same 14" drop.




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Gary


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I appreciate this thread and am very interested in the result. As we work on this next development it will be nice to know what the greatest challenge will be, then try to get that projector in, see if we can solve the most extreme case and then post screen shots.


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Shawn Kelly

Cygnus Imaging
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Discussion Starter · #11 ·
Shawn, Even though I am as disappointed as any, I have to say that your continued positive attitude and taking this just like any other setback in the quest to 'get it right' is nothing short of astounding...


I see from the other thread that you are getting a LT150 in over the weekend and from the specs it looks like that is one of mid range offenders but I would also venture that due to the short throw nature of Davis projectors plus their advanced beam spot size, all of which will put the edge of image farther 'down' the Pannie lens and create as bad an angle of intersection that it would be another good (read bad) testbed... Plus as these have a zoom you can test drop ranges with this machine that you would not be able to do with a fixed machine...


So Far the LT85 looks the worst according to the tale of the tape....


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Guys looking at the quoted figures here are some of the exit angles.



Lt100 with a 96" wide screen

Tele mode 14" 250.3" = 3.21 degrees

Wide mode 14" 192.1" = 4.17 degrees


LT150

10.3" 156.66" = 3.76 degrees


LT85

14.2" 156.66" = 5.18 degrees



Davis DL450:

Tele 14", 212" = 3.77 degrees

Wide 6", 143" = 2.40 degrees


Plus UP Series

Tele 14", 248" = 3.23 degrees

Wide 14", 191" = 4.19 degrees


VX1(LT100)

14" 228" = 3.52 degrees


Dwin Transvision 96" widescreen

Wide zoom: 6" 134.4" = 2.56 degrees

Long zoom: 6" 211.2" = 1.63 degrees


Yamaha DPX-1 - 96" widescreen

Wide zoom: 14.2" 189.6" = 4.29 degrees

Long zoom: 14.2" 224.4" = 3.62 degrees


Seleco HT-250

Wide zoom: ?" 222" = ? degrees

Long zoom: ?" 303.6" = ? degrees


NEC VT-540

Wide zoom: -5" 187" = 1.53 degrees (trouble wth chart?)

Long zoom: -5" 225" = 1.27 degrees


Sanyo PLC XP-30

Wide zoom: ?" 172.8" = ? degrees

Long zoom: ?" 213.6" = ? degrees


3rd decimal rounded up

I hope this helps.


DavidW




[This message has been edited by David Wallis (edited 09-02-2001).]
 

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We know the davis is a problem at least at 113" throw (I think this was the number form the other thread). Does anyone have the info to calculate the angle on the Davis?




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Discussion Starter · #14 ·

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Thus for Davis:


Tele 14", 212" = 3.77 deg

Wide 6", 143" = 2.40 deg


Thus my LT100 would appear to be worse!




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Gary,

As the former owner of both a Davis DL450 and an NEC LT100, I can say for sure that the LT100 has a greater image shift. I hope this gets worked out.
 

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Really need more specs from members on other units so you can find out all the models effected or not effected as the case maybe. What about all the LCDs etc


DavidW
 
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