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Discussion Starter · #1 ·
Please check my image below, but I ceiling mounted my projector this weekend and it's awfully low (18 inches) from my 8 FT ceiling, which makes it slightly above a 6 foot tall person.


My friends say it looks awfully low. Now I'm wondering if there is something wrong with my setup. Maybe it is the short throw?
 

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Hi,


It looks right. In ceiling mount position, the image top is higher than the projector. That means a very low mounting position of the projector.


regards,


Li On
 

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Looks Ok. IMHO To avoid having to correct for "squareness" using the digital keyestone correction, height from pj to ceiling and height from screen image to ceiling should be the same.
 

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Unfortunately, the 75U is the same way. Mine extends 19" from my 7.5' ceiling. I've already had one person 'bump' into it. For the size of image I'm projecting (measly 80" diagonal, 4:3), the center of lens is approximately 7.5" down from the top of the screen.
 

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Discussion Starter · #5 ·
Ok thanks guys. I thought I was doing something wrong because I'm used to seeing projectors close to the ceiling.


DMerrill - sounds like you're projector is quite low. Sorry to hear about the head bumping. I guess I should be glad I'm less than 6 feet tall.
 

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The AE100 manual has a diagram and a formulas to calculate the projection area. The lower edge of the projected image is lower than the center of the lens. Since your projector is up side down, the projected image will be higher than the center of the lens. They call that distance H1 in the manual. In your case H1 = screen with / 32, or H1=92/32, or H1=2.875". Since the distance from your roof to the center of the lens is 18", the projected image should be about 15.125" from the roof. I see that your image is only 11" from the roof, so make sure the projector is leveled. All this is on page 51 of the English manual.
 

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Discussion Starter · #8 ·
PSue,


(1) How low is your projector from your ceiling?

(2) How low is your ceiling?

(3) How low does your image start from the ceiling?


My image doesn't start right at the top of the screen.
 

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Try mounting this thing from a 15 foot ceiling!


I'm having a heck of a time!
 

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The relevant parameters are (a) the horizontal distance between the lens and the screen, (b) the vertical distance between the lens and the top of projected image, and (c) the keystone setting.


Yours:

(a) 13.5 ft,

(b) 7 inches below the image (image starts 11" from the ceiling and lens 18" down), and

(c) ?


Mine:

(a) 13.5 ft,

(b) 3 inches above the image, (image starts 12" from the ceiling and lens is 9" down), and

(c) 1.
 

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Discussion Starter · #11 ·
PSue,


Your setup is interesting. Where I've read the posts and the user's guide calculations, it always calls for the lens to be slightly below the top of the image in ceiling mount. In your case, the lens is actually 3 inches above your projected image and you only need a keystone of 1......amazing !
 

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President Bozo,


Good observation. The manual probably assumes the projector is horizontal; I have my projector pointing slight toward the ground. My criterion is to mount the projector at a height that the resulting parallax is correctable with keystone. If you are bumping into your projector, give my method a try.
 

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How would one avoid the keystone?
 

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Even a +-1 keystone adjustment will distort the image slightly. You can see it most easily by adjusting it with some text on the screen. Best bet is to mount the pj at the right height so you don't have to tilt it at all to position the image. This prevents having to use the keystone adjustment.
 

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After seeing how low this unti was mounted, I am slight confused.


I ordered a Preerless mount made for the AE100. The ceiling plate is 1.1", the adapter is 3.5" and the center of the AE100 lens looks to be about 2" from the bottom of the unit.


With no extensions, this would put the center of the lens a 6.6" from the ceiling. The formula on the English manual seems to indicate that with a screen width of 90 11/16 (104" 16:9 diagonal) and the AE100 mounted upside down, the image would be projected 2 13/16" higher than the cetner of the lens.


This would put it roughly 4" from the ceiling (6.6" - 2 13/16").


This seems nowhere near as low as this thread would indicate. Am I missing something?


- Jim
 

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Discussion Starter · #17 ·
jsalk


there is absolutely nothing wrong with your setup. in fact it is consistent with my setup. In my setup, the image is also about 2 inches above the center of my lenses.


But if you notice in my picture, my image starts about 16"

below my ceiling (yours is only 4 inches). I have an 8 FT ceiling and therefore it's uncomfortable for viewers if the image was any higher.
 

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Wow. So the native non-keystone adjusted image from the AE100 projects "above" an upright AE100 or below an upside down AE100, but not by a huge amount?
 

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President Bozo,


jsalk is 1" off ideal. He is probably keystone free.


The AE100 is a 16x9 projector and you should base your dimensions to that aspect ratio rather than a 2.35x1 ratio. At 16x9, you are 7" below the image. According to the manual, you should be 3" below the image to be perfect.


I think we are splitting hair. As long as the image looks OK, it really doesn't matter if the projector is off a few inches. I prefer to mount the projector as high as possible so it is less obtrusive. I want to watch movies; not the projector.
 

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cpc -


I think you have it reversed. If the projector is mounted up-side down, the top of image will be slightly higher than the center of the lens.


PSue -


I thought I was using 16:9. Please correct me if I'm wrong, but isn't the width of a 104" diagonal 16 x 9 screen 90 11/16"? I'm a little rustly with my math, but I used the formulas in the English AE100 manual and that's what I came up with. Did I miss something?


- Jim
 
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