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Discussion Starter #1
I'm about to buy a IF 7200. I've looked through every bit of documentation I can find about mounting and can't find one answer.


The lens of the PJ is off-center. Does the center of the lens need to be centered with the screen (left to right) or do the optics in the PJ adjust for the lens location, relative to the PJ itself, so that you mount the entire projector on center with the screen?


Did that make any sense?
 

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Lens should be centered to screen, left to right. If not, you will need to angle the projector, and then use keystone correction, which is not a good thing. Center it.


Mark
 

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I second Mark's answer. I have the 7200 ceiling-mounted. You must align the center of the lens to the center of the screen. My recollection was that the manual, though not necessarily clear about this specific point, gives the necessary measurements to accomplish this without too much pain. Just measure carefully. Compared to the vertical offset, the horizontal placement calculation is easy!
 

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Let me make sure I am following you guys. I mounted mine a couple of weeks ago and I don't seem to have any alignment problems but I want to make sure before I cut the sheetrock for the power and cables. Based on the IF documentation, the offset is 116%. Therefore, if (in their example) the screen height is 10' the offset would be 1.6' and that is with the PJ perfectly level (I put a small level across the housing of the lens to check. In my case, I have a 80"X45" firehawk. So the math I did (correct me if I am wrong) is 45"X.16= 7.2" offset from the top of the ceiling. My ceiling is 8 1/2' high so 7.2" put the screen too high for me. I went to Home D and bought a 4,6 and 8" X1 1/2" NPT galvanized pipe (in the plumbing section and a whole lot cheaper than the aluminum tubes online, I'll paint it black). I settled on the 6" tube for the right height. So, I added the 7.2"+ the drop from the ceiling (measured to the center point of the lens) and that is where I put the top of my screen. I still have a little keystone in the lower right hand corner but the velvet on the screen frame absorbs the light so it is not noticeable. I'll tweak it a little more before I take it down to finish the sheetrock.


Absolutely on centering L/R on the screen. I'm not sure why you would not have the PJ aligned on the centerpoint. Do you have an issue with a place to mount at the center point?


Are my calculations correct?
 

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Quote:
Originally posted by vshine


Absolutely on centering L/R on the screen. I'm not sure why you would not have the PJ aligned on the centerpoint. Do you have an issue with a place to mount at the center point?
Just so that the original poster is clear, the projector should not be mounted on center with the screen. Instead, the center of the lens should be centered, making the projector body slightly off center (since, as the original poster points out, the lens is on one side of the projector).


As for the offset (height or vertical alignment), it has been so long since I've done those calculations that I don't want to offer bad advice. There was a thread that discussed this in a great bit of detail back in February or March 2003. I believe that Bob Williams chimed in with some helpful hints.
 

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Discussion Starter #6
vshine: I haven't checked your math but the concept is right on as I understand it. That's one of the reasons I'm choosing the IF7200 (the 16% offset above/below the screen hight).


My question was well answered by JasonATL...assuming he is correct :) He also phrased it better than I. The bottom line is that the lens needs to be centered right-to-left, not the projector body.


I guess the obvious question then is why don't all of the manufacturers place the lens in the center of the body so that anal retentive folks like myself can center the projector AND lens?! (Sharp 9000/10000/12000 are all centered on their body so it must be technically possible)
 

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Which ceiling mount (InFocus, Chief, Peerless, etc) will allow the

7200 to be counted to the ceiling? How close can the

center of the lens be...... 3 1/2 " ??
 

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chief rpa 875 is what I recommend. works sweet!
 

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I have done a few installations and I favor using chief RPA mount with a adjustable extension tube and chief's lateral shift bracket.


The lateral shift bracket really makes centering the image easy and is worth the $40+ bucks. Its not easy to precisely mount a screen and PJ so that the image is PRECISELY centered. Suggest you consider using the LSB.

FYI, the bracket model number is LSB-100. chiefmfg.com/product_display.asp?id=4311


If you dont have vertical lens shift on the projector, having an adjustable length NPT rod gives you the same flexibility in vertical centering.
 
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