projector advice for lower ceiling, i beam obstruction - AVS Forum
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post #1 of 7 Old 07-18-2012, 08:04 AM - Thread Starter
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Hi guys,
I am long time reader, very infrequent poster.

I am looking to buy a new projector for the basement and was considering the Epson 3010, Acer 9500 or the HD33. The ceiling of my batcave is 7’2 and my throw distance is 13’. I am aiming for a projected image of 115-130’. In the center of room (6’ from the wall) there is a steel Ibeam that runs the length of the basement in front of the viewing area that drops down to 6’5. Ideally I would like to ceiling mount the projector, which would rule out the Epson 3010 for a ceiling mounted application due to zero offset.

My question is at that distance would the lens offset of the Acer9500, and the HD33 allow me to mount the projector relatively close to the ceiling and have the image clear the beam?

Furthermore, even if the image does clear the beam, will the combination of the lens offset and low ceiling result in the image being too low on the wall?

Finally, would I be better off with an Epson 3010 inverted on a shelf 6’5 from the floor for this application?

I have never owned a projector with lens offset and no/limited lens shift(currently own a ae700), so I am clueless about placement flexibility of these units. I was curious if others here have had a similar situation and what solution they came up with. Thanks in advance!
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post #2 of 7 Old 07-18-2012, 08:38 AM
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You didn't say how close to the ceiling the top of the screen will be located. I think you will find that most projectors with a fixed lens offset, i.e., no vertical lens shift adjustment, will not work for your situation as the ceiliing mounted projector must be located well above the top of the screen and with your low ceiling this is not possible. For example in the case for the HD33 with a 120" screen the center of the projector's lens must be about 8.5" above the top of the screen. You will probably need to move up to a projector with a vertical lens shift with enough range to allow you to locate the projector below the top of the screen. For the ceiling beam, does it run parallel to the wall where this screen will be located (this is what I assume, but its not clear from your post)? Assuming it is parallel to the screen and located between the projector and the screen then that means that the highest you can locate the projector will be less the 6.5' height of the beam (e.g. perhaps 5.5" depending on your screen location), as you must have line-of-sight from the projector's lens to the top of the screen. Most budget projectors lack a lens shift adjustment and usually require you to mount the projector above the top of the screen (or below the bottom of the screen if the projector is table mounted). Even the Acer 9500BD which has vertical lens shift, has a very limited range (+/- 12.5% or 25% total range) which given its starting point for lens offset does not appear to work for your case. You may need to get up to the $2,000 to $3,000 price range of to find 3D projectors with a wide range vertical lens shift adjustment to support your requirements.

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post #3 of 7 Old 07-18-2012, 09:19 AM - Thread Starter
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Ron,

Thanks for the reply. Yes the ceiling beam does run parallel to the viewing wall. I figured that the height of the top of the screen will depend on where the projected image falls on the wall after it clears the beam.

So if the offset of the HD33 is 8.5'' for 120'' screen, what if i used a drop pole and mounted the projector at a height of say 6'9. Using the elite projector calculator, it shows a 6.5' throw (distance from lens to beam) has a 4.7'' offset. Technically shouldn't the top of the image clear the beam? I apologize for my ignorance on this issue.
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post #4 of 7 Old 07-18-2012, 01:32 PM
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Originally Posted by capone428 View Post

Ron,
Thanks for the reply. Yes the ceiling beam does run parallel to the viewing wall. I figured that the height of the top of the screen will depend on where the projected image falls on the wall after it clears the beam.
So if the offset of the HD33 is 8.5'' for 120'' screen, what if i used a drop pole and mounted the projector at a height of say 6'9. Using the elite projector calculator, it shows a 6.5' throw (distance from lens to beam) has a 4.7'' offset. Technically shouldn't the top of the image clear the beam? I apologize for my ignorance on this issue.

From the HD33 spec. it appears that with a 13' throw distance (measureed from the front the projector's lens, and not from the center of the projector mount, to the screen ) the max. screen size that can be supported with the zoom set to maximum is 119" diagonal.

First select your desired screen size. The rule of thumb is the screen WIDTH should be about 2/3 of the seating distance or considered the other way the seating distance should be about 1.5 times the screen width). For example a 120" (diagonal) 16 x 9 screen is about 104 inches wide therefore the recommended seating distance would be about: 1.5 X 104 = 156" or 13'

Once you select the screen size then decide how close the floor you would want (or can accept) the bottom of the screen. For a 120" diagonal screen I like to keep the screen bottom perhaps 24 inches about floor level. For this example the vertical height of the viewable area of a 120" screen is 58" then add about 4" addtional for the frame/border (assuming a fixed frame screen with a 2" frame/border on all 4 sides). Thus the vertical height of the 120" screen is typically about 62" and if you were to keep the screen bottom 24" above the floor then the top of the screen would be just over 7' above the floor. Because of the beam across your room, if you were to mount your screen as in the above example then the projector would need to have lens shift since the projector would need to be located perhaps a foot below the top of the screen in order for the light path to clear the beam. In order to support a projector with a fixed offset, like the HD33, then the screen would have to be mounted much lower and the projector (lens location) could be mounted perhaps just a little higher that the bottom of the beam. Just how much higher than the bottom of beam will depend on the combination screen size, the projector-to-screen throw distance and the specific projector's fixed offset value.

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post #5 of 7 Old 07-18-2012, 02:29 PM - Thread Starter
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Thanks for the info Ron.

So it seems that the 9500 and the HD33 aren't going to work in my room. Do you see any issues with an inverted Epson 3010 shelf mounted, or ceiling mounted with a droptube at a height of 6'4? Thanks for your help!
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post #6 of 7 Old 07-18-2012, 03:19 PM
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Originally Posted by capone428 View Post

Thanks for the info Ron.
So it seems that the 9500 and the HD33 aren't going to work in my room. Do you see any issues with an inverted Epson 3010 shelf mounted, or ceiling mounted with a droptube at a height of 6'4? Thanks for your help!

The Epson 3010 also lacks lens shift but in its case when ceiling mounted it's my understanding the vertical center of the projector's lens should be at the same height as the top of the screen's viewable area. Thus if you mounted the projector such that the center of the lens is 6'4" above the floor then the top of the viewable area of the screen should also be mounted at this same height. For a 120" screen this would mean the bottom of the screen would be just over a foot above the floor. If you were to go this route I suggest you allow at least of couple of inches of extra clearance below the ceilaing beam and the light path from the projector's lens to the top of the screen.

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post #7 of 7 Old 07-19-2012, 08:46 PM
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Quote:
Originally Posted by capone428 View Post

Hi guys,
I am long time reader, very infrequent poster.
I am looking to buy a new projector for the basement and was considering the Epson 3010, Acer 9500 or the HD33. The ceiling of my batcave is 7’2 and my throw distance is 13’. I am aiming for a projected image of 115-130’. In the center of room (6’ from the wall) there is a steel Ibeam that runs the length of the basement in front of the viewing area that drops down to 6’5. Ideally I would like to ceiling mount the projector, which would rule out the Epson 3010 for a ceiling mounted application due to zero offset.
My question is at that distance would the lens offset of the Acer9500, and the HD33 allow me to mount the projector relatively close to the ceiling and have the image clear the beam?
Furthermore, even if the image does clear the beam, will the combination of the lens offset and low ceiling result in the image being too low on the wall?
Finally, would I be better off with an Epson 3010 inverted on a shelf 6’5 from the floor for this application?
I have never owned a projector with lens offset and no/limited lens shift(currently own a ae700), so I am clueless about placement flexibility of these units. I was curious if others here have had a similar situation and what solution they came up with. Thanks in advance!


I have almost the exact same issue as this in my HT room. I'm working on some ideas right now, so I'll keep you posted on any possible solutions I may find. You likely will have to get a unit with Lens Shift to keep your image as high as possible.

I'll be posing this problem with a diagram in the "HT Build" forum sometime tomorrow, so take a look there. They know their stuff and really try hard to help on these matters. i know how you are feeling, as I've been back and forth on the right projector for this reason. Good luck.

Rich

"I don't think you fully understand, Bigelow... you've been murdered."
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