distance from ceiling

[bgrounds]

I am new to the PJ arena. I have a white drop ceiling in my basement. How far away (below) does the PJ need to be so there is no light "bleeding" onto and reflecting from the ceiling?

Thx

 

[TVJon]

The light beam from the projector is pretty directional. I have a hunch the reflection from the screen back onto the white ceiling in the front of the room will be much more of a distraction. I have my PJ about a foot down from the ceiling and it's not an issue.

For what it's worth, I also have my screen wall painted black, with dark cabinetry and a tray ceiling around it. The screen pops and the wall disappears, just the way I want it.

TVJon

 

[Stormwolf]

this is a little off topic but fits under subject. I am also going to be purchasing a pj soon (1st ever). My question is how should the screen be located from the ceiling/floor?

Should it be tight to the ceiling or have a drop from the ceiling?

Thanks and sorry for adding a question to your post

 

[TVJon]

I'm relatively new to this as well, but a couple of factors come to mind. The most important would be viewing angle -- put the screen too high and it might be uncomfortable to tilt your head back to watch for long periods of time. The second factor is the ability of your projector to shift the image up or down without distortion. This comes into play if you ceiling mount your projector. Lots of makers and projector sales sites have screen distance calculators and specifics on picture-shifting abilities of various models. From what I understand, DLPs are more limited in this regard, than LCD projectors.

TVJon

 

[Bryce_H]

The manual should have all the calculations of the measurements for the projector to the screen (i.e. how much the projector should be above the top edge of hte screen)

With respect to the "bleed" question - you will get some light splash from the picture onto teh ceiling. You might consider painting the ceiling a dark grey(that what I did with my setup)

 

[chadnliz]

My Pro is about 6in from drop ceiling and its white with no issues, the screen position is also key so that you can place a center channel beneath it or amps and such, also if you are ever going with a second row they wont be able to see the bottom of screen if it sits really low. My screen sits 3oin from floor and I like its height but I have a low ceiling at about 79inches so I only went with 84in screen for the very reason I listed above.....floor clearance. I think I have somewhere around 6-8 inches from ceiling to screen.

 

[KevInCinci]

My projector is only a few inches from the ceiling and I do get some light splash on it. However, it's behind my seating position, so it doesn't have any effect on my viewing experience. I wouldn't worry about it too much.

As for screen position, I read somewhere on here when installing my screen that you should aim for your viewing point to be something like 1/3 of the way from the bottom of the screen, obviously with 2/3 of the screen above where your eyes would be. Mine ended up pretty low to the floor (maybe 30"), but it's actually great for easy viewing. I always felt most people with projectors put their screen up too high without thinking about it.

Cheers,

Kevin

 

[majorloser]

Here's a nice little calculator that help figure out size, throw and distance from screen:

http://www.projectorcentral.com/projection-calculator-pro.cfm

You really shouldn't have any problems with light refletions off of adjacent walls or ceiling. Today quality projection screens help limit the amount reflections to off angles - half gain.

Definition from Stewart Filmscreen:

Half Gain Viewing Angle
Half gain is the standard that the projection screen industry uses to measure the brightness performance of a projection screen when the viewer is observing the screen from am extreme angle or "off to the side".

A projection screen's peak brightness is when the viewer is directly in front and perpendicular to the center of the screen. This is referred to as Peak Gain at Zero Degrees Viewing Axis. As the viewer moves out to the side of the center of the screen axis, the brightness of the projected image will drop off. When the brightness drop off angle reaches 50 percent of peak gain, which determines the screen's half gain (or half brightness) viewing angle specification.

Example: Let us say a projector screen has a peak gain of 4 and its output is 22 Foot Lamberts when directly in front of the screen at zero axis. Let us say the screen's half gain specification is at 52 degrees. That means that when a viewer is seated at 52 degrees of center screen, the viewer would observe half the brightness as a viewer that is seated directly in front of the screen - 11 Foot Lamberts - Gain of 2.

 

[robbyelectro]

looking to prewire for a overhead projector, and I am wondering how far away from the wall ( screen ) should I put the wiring and outlet.
also what is a good type of Projector/
thanks ahead of time
Robby

 

[KevInCinci]

looking to prewire for a overhead projector, and I am wondering how far away from the wall ( screen ) should I put the wiring and outlet.
also what is a good type of Projector/
thanks ahead of time
Robby

Robby,

I think it's really hard to generalize the distance such that it will fit all projectors. The type of projector, the size of the screen, room dimensions, seating location, brightness, etc., all factor in to where you mount it. Some projectors like the Optoma DLPs need to be placed within a very narrow window; others (LCD) are much more forgiving with zoom and lens offset. If I had to come up with some numbers, I'd shoot for somewhere in the 12'-15' range from where the screen will be. With a 3' power cord and/or video cables, that gives you get a pretty broad range of placement. Any closer than about 10' and the image is going to be pretty small (ok if you're using like a sub-90" screen). Too much farther and you might lose some brightness. You could go as far as your back wall, but some projectors might have the image on the floor if that's a long way away. Whatever you do, I'd recomend running a conduit through which you can add or change the cables from where your receiver is to the projector.

Cheers,

Kevin

 

[BMXTRIX]

To answer some questions here...

1. The projector can be placed anywhere in the room - from floor to ceiling - without any issue related to 'splash'. This actually only occurs when light bleeds out of the casework of the projector and typically indicates some flaw in projector design. So, generally, hugging the ceiling is fine.

2. You SHOULD place a projector at least a couple of inches from the ceiling, or more, to help with air flow around the projector.

3. You MUST put the projector at the point where it is required by manufacturers. With DLP projectors, that can be about 30% above the top of the screen (if the screen is 50" tall, then 30% of 50" = 15" above the top of the screen!) - DLP can have some serious limitations due to this fixed lens offset on many models. Better, are the DLP models with lens shift (typically more $$$) or the LCD projectors with lens shift. Lens shift gives you a range of area where the projector can be placed. Kind of like zoom on a camera allows you to be closer or further away, lens shift lets you raise the projector up and down while still having a perfect image.

4. Do NOT use keystone correction! Keystone correction is a digital correction which people confuse with lens shift. While lens shift is an optical correction and maintains perfect image quality (with good optics), keystone correction actually must lower projector resolution to perform. If you bought a 720p projector, the second you use digital keystone correction you are no longer using a full 720p projector.

5. The projector itself must be placed within the zoom range from the screen. This range is entirely dependent on the individual projector and the screen size.

6. Pick a screen size FIRST, this should be based upon your expected seating distance. THX (movie theater) standards put the center seats of a theater about 1.5x the screen width. So, if you are seated 12 feet from the screen, you want about a 96" wide screen or about a 110" diagonal screen (1.78:1 screen ratio).

7. With a 110" diagonal screen, go to Projector Central (dot com!) and pick out a few projectors you are interested in and use their projector calculator tool. For 110" diagonal, most projectors will fall in the range listed above - about 12-15' from the LENS to the screen.

8. Some projectors, such as the very popular AX200U from Panasonic, have a LOT of zoom range and you can put the projector 11-22 feet from a 110" diagonal screen. Other projectors, like the cheaper 720p DLP models, only allow you to put the projector about 12 to 13 feet from the same screen. So, having a good idea of your projector is good to have before you buy.

9. If at all possible: RUN CONDUIT! Or leave some other access between the projector location and the equipment location. I typically use an extension cord and plug it into my surge supressor with my other equipment and then run my cabling. This way I have my projector surge protected, and on the same circuit as my other gear. With the conduit or retrofit access, I can always put the cabling exactly where I want it. But, when I do an installation, I always find the projector FIRST, then put it where it needs to go for the screen that will be used.