Help...Where to mount the Projector?

[SMM]

Builing a Home Theater in my basement. The room is 22 x 15 with a finished ceiling height of approx 86". The 92" diagonal screen will be on the far end of the 22' stretch with two rows of recliners on the opposite end. Where along the ceiling and at what height do I mount the Infocus IN76 projector? at what height do I mount the 92" fix screen

 

[cthomp]

Builing a Home Theater in my basement. The room is 22 x 15 with a finished ceiling height of approx 86". The 92" diagonal screen will be on the far end of the 22' stretch with two rows of recliners on the opposite end. Where along the ceiling and at what height do I mount the Infocus IN76 projector? at what height do I mount the 92" fix screen

The placement of your projector will be predicated on the model of projector and the screen size. You will find a useful projection calculator at:
www.infocus.com/ProjectionCalculator.aspx?itemId=in76

It looks like for the IN76 and a 92"d screen, the ideal distance would be between 10.2 and 12.9 feet. Screen gain could also play a part in your selection.

A 92"d screen is 45"h. The ideal viewing height is 42" one third up from the bottom of the screen. This would put the bottom of the screen 27" off the floor and the top of the screen at 72". That would result in the top of the screen being placed at 14" from the ceiling. Many projectors are mounted so that the center of the lens is placed even with the top of the screen. This can vary with projector depending on lens offset and type. I would contact InFocus customer service for their recommendation. Hope this helped!

 

[mtrycrafts]

Builing a Home Theater in my basement. The room is 22 x 15 with a finished ceiling height of approx 86". The 92" diagonal screen will be on the far end of the 22' stretch with two rows of recliners on the opposite end. Where along the ceiling and at what height do I mount the Infocus IN76 projector? at what height do I mount the 92" fix screen

cthomp made some great input for you. I'd recommend hanging the projector so that the lense is at the minimum throw distance from the screen and as he said, down from the ceiling so the lens is at the same distance down as the top of the screen is, even if the company tells you it could be higher; this may cause some keystoning and not be totally compensated for. 14" down from the ceiling is not much. You could build a nice enclosure around it.

The lamp will loose intensity over time and you will loose it as you increase the distance back.

Make sure you have several video cables to it, just in case: HDMI/DVI, component, and is you have cable TV through a VCR, or later from a digital cable box.

If it is a fixed screen, no trigger line. But, you may want to install a remote sensor line so you can turn the projector on/off from your seat and maybe other components as well.

 

[BMXTRIX]

I would not put the lens at the minimum, but closer to the maximum throw distance. This will minimize hot-spotting and will have zero impact on the light output of that projector. Very few projectors have zoom lenses that impact light output.

Keep in mind, the zoom range is from the front of the LENS, not the middle of the projector. So, if your mount is at 12.9 feet, the lens will be closer to 12 feet or so from the screen... that's a pretty good/safe distance.

As for projector height - if the screen is about 12-16 inches from the ceiling to the actual top of the viewing surface, then the center of the lens of the projector must be 7.2 inches above the top of the screen so that you have zero keystoning issues. This is the proper height to mount it at.

According to this page:
http://www.infocus.com/service/in72/in72.asp?site_lang=1&site_region=1&

The lens offset is 116% which (if I did that math right) is the 7.2" I indicated. This is not bad at all as some projectors force you up 18+" for the same size screen.

Note: IMO, that is a very small screen for that size of a room and I would be looking more in the 110" to 120" diagonal range.

 

[cthomp]

Offset calculation

The lens offset is 116% which (if I did that math right) is the 7.2" I indicated. This is not bad at all as some projectors force you up 18+" for the same size screen.


BMXTRIX,

Just curious how does the math work for calculating the offset?

 

[BMXTRIX]

Since there is no manual that I have found I am going by the 116% being in relation to the screen height. Typically offset is measured from the top of the image to the center of the lens in an 'upright' configuration.
H = height of the screen (45")
Offset = height of screen + distance to center of lens (45" * 116%) = 52.2"
H' = Offset - H which is 7.2"

That's if they did things typically... which I can't tell for sure without a specific owners manual.

 

[cthomp]

Calc

Ok, got it, I think...........

So basically, if the center of the lens should be mounted 7.2" above the top of the screen, and the average ceiling mount puts the center of the projector lens at say 7-8", the end result would be to place the top of the screen viewing surface at 14-15" from the ceiling??

Thanks BMX

 

[BMXTRIX]

If that's the type of mount used. I always, and ONLY recommend using something like the Chief mounts. The RPA series is a bit more expensive, but they use 1.5" pipe that can be purchased at your local hardware store. This pipe can typically be bought in 1" increments from 2" to 12" at the store! This means that you can really get the projector hung at the exact height you need it at within half an inch or so. Plus, the pipe is far more durable than what comes with a lot of the cheapie projector mounts.

You do have the math right though... If you have a fixed mount that forces the center of the lens to be 8" from the top of the ceiling, then the screen's top viewing edge should be mounted about 15" from the top of the ceiling.

This is more of a situation where it may make sense to first mount the projector, then put the screen up so that it matches perfectly.

 

[cthomp]

Good stuff to know. Thanks BMX!

 

[mtrycrafts]

Ok, got it, I think...........

So basically, if the center of the lens should be mounted 7.2" above the top of the screen, and the average ceiling mount puts the center of the projector lens at say 7-8", the end result would be to place the top of the screen viewing surface at 14-15" from the ceiling??

Thanks BMX

Before you make this a concrete distance above the screen, better check with the projector maker(call them for clarification) as they usually have a range of height from the center of the screen up an X amount, or down. I am willing to bet that this is their upper limit before keystoning is a factor.
Probably want to do the same inquiry about their throw distance and light output fall off.

 

[BMXTRIX]

Before you make this a concrete distance above the screen, better check with the projector maker(call them for clarification) as they usually have a range of height from the center of the screen up an X amount, or down. I am willing to bet that this is their upper limit before keystoning is a factor.
Probably want to do the same inquiry about their throw distance and light output fall off.

Mtry - This specific projector has a fixed lens. It doesn't offer lens shift like the Z4 or AE900 projectors which means that for any given screen size, at any given distance, there is only one spot that the projector can go without using keystone correction. The specs for the projector call it 116% offset... but doesn't give additional information. I most definitely would call the manufacturer to confirm this before buying that projector just to confirm this since ceiling height is an issue.

That, or see if you can get your hands on an instruction manual for the projector as this should have more detailed info than what I got from their one page spec sheet.

EDIT: They either added, or I missed, specific info for this projector right on their website...
http://www.infocus.com/service/IN72/faq-installation.asp?site_lang=1&site_region=1&cat=offset

The number - 7.2" seems to be accurate and consistent.

 

[mtrycrafts]

Mtry - This specific projector has a fixed lens. It doesn't offer lens shift like the Z4 or AE900 projectors which means that for any given screen size, at any given distance, there is only one spot that the projector can go without using keystone correction. The specs for the projector call it 116% offset... but doesn't give additional information. I most definitely would call the manufacturer to confirm this before buying that projector just to confirm this since ceiling height is an issue.

That, or see if you can get your hands on an instruction manual for the projector as this should have more detailed info than what I got from their one page spec sheet.

EDIT: They either added, or I missed, specific info for this projector right on their website...
http://www.infocus.com/service/IN72/faq-installation.asp?site_lang=1&site_region=1&cat=offset

The number - 7.2" seems to be accurate and consistent.

OK, thanks. That is what it appears to be, fixed offset, period. No need to call the maker. I didn't see any hint that this would be the max offset.

 

[BMXTRIX]

OK, thanks. That is what it appears to be, fixed offset, period. No need to call the maker. I didn't see any hint that this would be the max offset.

If you read about any projector's specifications, look to see if the projector has lens shift. Not to be confused with keystone correction. If the projector has horizontal/vertical lens shift than that means it can be moved up/down/left/right and some correction can be made optically. If the projector specifications say that the projector does NOT have lens shift, then the projector has one, and ONLY one spot that is ideal, otherwise keystone correction must be used.

In the days of CRT projectors you basically always had to get the placement of the projector perfect. Most LCD projectors for home theater use include lens shift. Most higher end DLP projectors include lens shift. It is ONLY the inexpensive (sub $5,000) DLP projectors that typically do not have lens shift and should be checked carefully prior to purchase.

The very popular InFocus SP4805 projector (about $1K) has a good bit of offset and no lens shift which means that it is very poorly suited to basements with low ceilings (6-7 foot). Likewise, one of the cheaper models they just came out with has 128% offset (screen height *.28 = offset) which means that on a 100" diagonal you have to mount the screen a good foot below the lens - which is pretty low on a 7 foot high ceiling... and a lousy decision considering the budget and price point - hence location, many people may be putting this projector.