Panamorph UH480 and ATH1 sled - image shifted left off of screen - AVS Forum
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post #1 of 7 Old 06-19-2013, 06:40 AM - Thread Starter
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Looking for some help here as I have hit an unexpected problem. I have a JVC X55R projector and the UH480 lens and automated sled, all mounted on the Panamorph plate and Chief mount. I have a small room so I thought I would mount the projector and lens in the closet at the rear of the room where my other equipment is to allow for a longer throw distance. However, I had to shift the whole install to the right by probably 10" due to the door jamb being in the way so I am not horizontally centered to the screen. I thought, no problem I have lots of lens shift available in this projector. I can get my 16:9 image with 98" width centered just fine. When I move the lens into position for 2.35:1 the resulting image is shifted off the screen by maybe 12" or so to the left when facing the screen. I remembered the twisting adjustment available through the slotted screws on the lens sled so I tried that. It did help some but not enough. If I remove the lens from the bracket and just hold it up in front of the projector lens I can get the image right where I want it. Is the horizontal lens shift I'm using in the projector causing the issue? I guess I can move the whole thing forward, out of the closet but I will loose about 2' of throw distance that way. I think this would put the lens front at about 14' from the screen and throw ration of 1.71. I believe this is still within the Panamorph mounting guidelines and would allow me to horizontally center the whole setup to the screen wall. Suggestions?
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post #2 of 7 Old 06-19-2013, 08:32 AM
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Yes,the problem is very definitely the horizontal lens shift, which is a problem for all anamorphic lenses. Vertical lens shift is ok, but not horizontal. An inch or so of horizontal can be compensated for, but 10" is way outside what most would consider acceptable in terms of picture distortion. Not only will you have the problem you describe, you will also have some noticeable geometric distortion in that the picture will be taller on one side of the screen than the other.

Your suggested solution is still within the proper throw ratio and distance parameters of the 480. You will have slightly more pincushion, but at least the pincushion will be evenly spread out and easily compensated for by zooming slightly into the screen surround.

What is you screen height?

Hope this helps!

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post #3 of 7 Old 06-19-2013, 08:57 AM - Thread Starter
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John, thanks very much for the reply! My screen height is 55.3". The image width is 98" for 16:9 and 130" for 2.35:1. I'm projecting on the wall at the moment as I have not yet purchased a screen. I'm looking at the Seymour AV accoustically transparent fixed frame models. I was surprised that I was able to get the scope image centered perfectly when just holding the lens up in front of the light path. Trying to look up at what I was doing in the dark it appeared the UH480 was turned at a very slight angle at the rear lens opening to get the image centered. I don't have a way to make this type of adjustment when the lens is on the sled. I hate to pull the whole thing down but if another sweaty trip into the attic back and forth will help then I would rather get this right. Moving everything out of that rear closet would also mean I could and would also need to, mount the projector closer to the ceiling. As it hangs now it's on about a 14" drop in order to clear the top of the door jamb. I know it sounds like a weird setup but you do what you have to do in a small room I guess.
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post #4 of 7 Old 06-19-2013, 09:03 AM
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OK, 3X screen height is 13.75' so you are ok there.

Have you used the full amount of adjustment to shift the image? Our Installation Video shows how to accomplish this:

http://www.panamorph.com/8-support/videos

If you can get the image centered using the method in the video, you can evaluate for yourself whether or not the resulting image distortion is bothersome. Since you don't have a screen as a reference, I would measure the left and right side height of the image on your wall to see how much this affects things.

Good luck!

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post #5 of 7 Old 06-19-2013, 09:18 AM - Thread Starter
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I have seen the video before and watched it again recently. It is helpful and it did remind me about the slotted hole adjustments on the slide. Even at full adjustment it doesnt' get the scope image centered but it did help. If I could replicate what happens when I manually hold it up to the light path I would be good. More testing to be done...
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post #6 of 7 Old 06-19-2013, 11:47 AM - Thread Starter
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I also just read this in the installation manual.

"The AKPro attachment plates are designed so that the projectors and other attached components form an average center of mass (gravity) approximately located at the center of the ceiling mount pipe. Therefore, the ideal ceiling mount location will be shifted by the AKPro 2" toward the left side of the screen from the ceiling mount location indicated by your projector's instructions. If the plate is to be inverted (as directed in the plate diagram document) this shift will be to the right side of the screen."

I guess this might also be contributing to the problem. If I do move everything closer I will need to make sure I'm centering everything based on the projector lens location on the mount.
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post #7 of 7 Old 06-20-2013, 07:05 AM - Thread Starter
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I pulled the projector down last night and did a very rough setup with it sitting on a very low ottoman, too low to the floor really. I reset all of the horizontal lens shift I was using and physically centered the projector lens to the screen wall. Got out the tape measure an made sure my 16:9 image was within 1/4" of being centered on the wall. I took the lens bracket apart and put it all back together to make sure everything was centered on that again. Tightened up the sled screws and recentered all that. I was able to get my scope image centered without even touching the yaw adjustments on the sled. I guess the horizontal lens shift really was screwing things up. It also looks like the shorter throw resulting from moving the projector out of the closet and centering it to the screen won't be a problem as I think I can handle any distortion with masking if necessary. Now, I just need to mount the projector again. My Panamorph setup came with a really short Chief conduit (maybe 3") and a nice ceiling flange. I guess I will use this which will get the whole thing much closer to the ceiling.
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