Front Projector Installation

[Kilwox]

Hi all. I'm purchasing my first front projection system this week, an Optoma H-31 and a 92" manual pull down screen, and have a few questions regarding the installation. I'm assuming that I would install the screen first where it needs to be in the center of the front of the room, then work on mounting the projector a reasonable distance back from the screen.
Are there any installation tips or tricks I should keep in mind when doing this? The package I bought includes a ceiling mount, but how do I ensure that the projector is the correct distance down from the ceiling? How do I figure out what that distance is?
I'm just looking for a little help from some of you with a little experience in this.
Thanks

 

[RLA]

Hello
Actually you have it backwards. The H-31 has no horizontal or vertical lens shift. Install the projector in its neutral level geometrically correct position.

Project a test pattern on the wall, size the image to the screen size mark the wall and then position the screen.
Doing the install in this order prevents the use of keystone correction and
Insures the projector is square with the screen

 

[BMXTRIX]

Simply look at the owners manual for the H31, it will tell you how far above the top edge of the screen you must mount the projector and how far back it may be mounted.

For a 92" (diagonal?) screen you may mount the projector (typically front of the lens) between 11 feet and 13.4 feet.

For perfect image, the projector should be mounted about 15 inches above the top edge of the screen (center of lens).

 

[Kilwox]

screen placement

Due to the configuration of my room, I can't mount the screen right against a wall. When retracted, I hope to mount the housing approximately 30" infront of the front wall. Will this affect how I mount it? I will make sure it is centered between the side walls, and that it is perfctly parallel to the front wall.
Also I'm expecting a copy of Digital Video Essentials in the mail in the next couple of days. Will that have an appropriate test pattern I can use to position the screen properly?

 

[RLA]

You dont nessessarly need to mount the screen on the wall
The retracable screen will have some adjustment built into it for the drop distance.Having the lense square and level with the projecting surface will insure correct projecting geometry you dont want the image to look like
this / \

DVE will have all you need for calibration.Be paitent,take your time
to get the mechanics correct no amount of keystone or skew should be used on a good install

 

[BMXTRIX]

RLA - The screen probably won't have adjustable borders. It sounds like the manual screen that comes within a package. Maxes out with the screen a few inches outside the case, then retracts inside. A good, but cheap screen that many of us may have started out with.

If you need to lower it more, those cases usually come with eye-hooks that you can thread a chain or string through. You will want to make sure you are hanging the screen from ceiling studs as well.

If you want the best image, then you will want to avoid digital keystone correction which does mean that the top edge of the screen should be about 15 inches below the center of the lens when open. You will have to do some measuring to get this all figured out on your own. Not very difficult really, but takes some time.

RLA has it dead on: "Be paitent,take your time.."

 

[Kilwox]

I'm sure that the screen will have to hang from the ceiling by about a foot. I thought of chain or string, but is there a better way to ensure that the screen doesn't sway? Any reccomendations for a rigid rod I can use to firm up the screen housing? I want to make absolutely sure that it remains perfectly square to the projected image.

 

[BMXTRIX]

You can use just what you said:

A threaded rod.

Threaded rods are available at your local hardware store and there are any number of brackets and ways to secure it to your ceiling so when the screen is mounted it is stable and doesn't sway at all. Likewise, there is steel L shaped bars that you can buy that have holes in them for mounting.

Perhaps some L brackets? A long one to secure to the ceiling and drop down, and a short one to actually mount to the screen?

You have a pretty long list of options and a quick walk through Home Depot will get you what you need, plus a half dozen tools that you forgot you needed.

 

[RLA]

Hello
One more thing to keep in mind and this pertains to all projectors.
If you install the PJ at or nearer to the end of its TD you will have significant filtering effect. This can lower CR ratio and lumen output by a significant margin. Choosing the correct gain for the screen should also be considered.
If this is a packaged screen chances are you wont have a choice

 

[Kilwox]

The screen is the packaged screen that many dealers are selling with the H-31. It's a Grey Wolf screen resold by Optoma with a gain of 1.8. I hope this will satisfy my needs. I was hoping that Optoma would attempt to bundle a screen that would augment the capabilities of the projector reasonably well.

 

[BMXTRIX]

...this pertains to all projectors. If you install the PJ at or nearer to the end of its TD you will have significant filtering effect.

Not arguing, but wondering where you got this information from?

I spent a few years as a photo major and would think that optics play entirely into this and manufacturers really are the dermining factor in how much loss is a part of the zoom process. Some would allow more zoom, and compensate with better optics. Others would use less zoom, and cheaper optics. Others will use more zoom and cheap optics and have a more severely affected image towards the end of the zoom range.

Or lens shift range as well.

I think some of this information is covered in the new AE900 and Z4 reviews on Projector Central as they talk a bit about image fall off with zoom and lens shift. Not in great detail mind you.

But, my point is: Wouldn't the optics of the lens and the amount of tolerance and quality built into that lens really determine if there is any filtering effect? I know in the photography world there is a reason why Nikor lenses tend to cost a pretty penny more than the Vivitars. It is a lot more than brand name.

Just looking for your insight on this.

 

[RLA]

BMX
It' s a trade off but I find that filtering effect has a huge impact on
CR and brightness and the 1/2 waypoint of the zoom range may be a happy medium. Photo and projection are two different animals digital projection systems rely on a bulb and light engine to generate images. I will agree that optics do play a major role in the performance of any digital projector and this role is often overlooked by the videophile.

Many are begging the industry for new technologies, 1080p comes to mind but they overlook the importance that optic and lens technologies play.
Higher resolution will not guarantee better performance. I will take a low res projector with great optic's over a high res projector with poor optics any day Or a low end projector that has been installed correctly and dialed in
Over a high end projector that has been installed incorrectly.


I generally don’t like to link to other forums because I find the information contained in the forums is accurate, but in this case I trust this persons conclusions as it mimics my own findings.

http://www.avsforum.com/avs-vb/showthread.php?t=586260&page=22&pp=30

Please see Darins post 1/2 down the page The filtering effect is not exlusive to the AE900

One more thing, many HT's have 8 or 9 foot ceilings placing the PJ at the very end of the room far from the screen increase's shadow effect as well

 

[BMXTRIX]

I think that it excellent information and is something that I should have been aware of. 'Filtering'? I haven't heard this term.

It seems that this is much more likely an aperature issue as was pointed out a few posts below. As with most zoom lenses as the lens is zoomed in, the optics aren't large enough to allow for full light flow so the aperature is closed down.

Yeah, seems much more likely that good optics with a fixed aperature would help to maintain brightness and contrast uniformity across the full zoom range. Which, I believe is why many projectors don't offer such a wide extent to their zoom range.

Flexible? Yes! Perfect? Not even close. But still, the image from the newer LCD units is pretty phenomenal for the cash.

What exactly is shadow effect as this is not a commonly referred to term on either Projector Central or even within the AVS Forum. A few references, yes, but nothing specific. Google didn't help me much either after a quick search.

 

[RLA]

What exactly is shadow effect as this is not a commonly referred to term on either Projector Central or even within the AVS Forum.

That’s because PJC doesn’t install projectors
Shadow effect or broadcast is when something or someone interferes with the light path directed at the screen It can be an object or light or?

 

[BMXTRIX]

Okay, so shadow effect is something to be aware of, and not a problematic issue is what it sounds like to me.

I just was like - whoa, that sounds bad, when you say: "...placing the PJ at the very end of the room far from the screen increase's shadow effect..."

But, the potential for shadows caused by furniture, celing fans, lamps, tall people, etc. is what you are actually referring to. This means that people really just need to be aware of it.

I've never even thought about it as I just am used to casting a shadow when I step in front of the light path of my projector and don't mind it a bit. Usually, because when I'm walking around, I've already pressed the pause button.

But, I guess in a more social room instead of a dedicated theater where you may be watching a football game and have snacks and stuff out, placing the projector at the back of the room may cause some level of irritation for people just trying to watch the game.

"Hey you! Down in back!"

Just give me a really short throw lens and let me do rear projection okay?

Thanks.