Canadian TV, Computing and Home Theatre Forums banner
1 - 13 of 13 Posts

· Premium Member
Joined
·
9,579 Posts
rvs007 said:
Seating area will likely be 12' from the screen wall.

According to the distance caculator on Optoma's website, I can achieve a 130" image dialgonal if I mount it at 15'-5" from the screen. ... Based on this, the image will be 4" off the floor ...
In my opinion, 4" off the floor is too low:
- It will cause you to have to look down, rather than straight ahead.
- You won't have room for a center channel speaker. (The bottom of my screen is ~24" off the floor.)

Also, keep in mind that 12' from 130" means that DVD-quality video or poorer is going to look like crap. I sit 13' from my screen and, while DVD-quality video is fine, I wouldn't want to be sitting any closer.
 

· Premium Member
Joined
·
9,579 Posts
Do these projectors allow vertical adjustment of the image so that I can shift the image higher (closer to the ceiling) and gain for more space below the image?
Depending on the projector, you can get horizontal and vertical lens shift, and keystone adjustment capabilities. (You want to avoid keystone adjustment as much as possible.) See what the specs for your projector say. A good site for info. is ProjectorCentral.com.

(Edit: According to the site, the Optoma HD20 has vertical keystone adjustment capabilities only.)

However, if I were to keep the viewing distance at 12' from the screen, what would be the ideal screen size?
That's too subjective a question to answer definitively. At 13', I think 100" is great. 106" might be just a little bit better. 120" would be too much, especially for DVD-or-poorer video quality. At 12'? I wouldn't go over 100". YMMV.

Since the mounting location for the projector is flexible at the moment, I could also move the projector closer and reduce the screen size a bit.
Use the Projection Calculator on ProjectorCentral.com to help you find the mounting point.
 

· Premium Member
Joined
·
9,579 Posts
I don't think you'll find many (any?) 1080p projectors with lens shift at the ~$1K mark.

But, do you need lens shift? I just ran the calculator and, if you mount the HD20 at 13' (lens to screen), you can get a 100" image (87" (w) x 49" (h)).

Middle of lens to top of screen is 7.8". You are planning to mount 6" down from the ceiling, so that's 13.8". Add the distance from top of mount to middle of lens - say, 4" - and you're at 17.8". So, 17.8" (ceiling to top of screen) + 49" (height of screen) = 66.8".

You have 7' ceilings = 84", which leaves you just under 18" of space for a center channel speaker.

However...
- if 'top of mount to middle of lens" is less, or
- if you tilt the projector up slightly and apply a bit of keystone adjustment, or
- if you mount less than 6" down from ceiling,
...you'll have more room under the screen, or you might be able to go with a slightly larger image (106"?).

Just my 2¢... :)
 

Attachments

· Premium Member
Joined
·
9,579 Posts
Another option - not my preference, and not always possible or practical - is to mount the center speaker on the wall above the screen, where you've got over 17" of usable clearance, and angle it down toward the seating area. With no speaker under the screen to worry about, you don't have to resort to any lens shifting or other adjustments, and you can go with a (slightly?) larger screen.
 

· Premium Member
Joined
·
9,579 Posts
120" screen.

6" + 4" + 9.4" = 19.4"
19.4" + 59" (height of screen") = 78.4"

This puts the bottom of the screen just under 6" off the ground. At the top, you've got 19.4" - 3" (see below) = 16.4" of space for a shelf and center speaker.

-----------------------
Assuming a fixed-frame screen, the frame is usually ~3" wide. So, while there's 19.4" of space from ceiling to top of screen, there's 16.4" from ceiling to top of frame.

In the example with the 100" screen, the amount of space at the top should actually be just over 14".
 

Attachments

· Premium Member
Joined
·
9,579 Posts
I was planning to project onto a white wall. Is there advantages of using a fixed-frame screen over a white wall?
A screen (fixed-frame or otherwise) will be designed for optimal light reflection, and it will offer a perfectly flat surface.

If your wall is perfectly flat, there's no harm in throwing an image onto it and seeing how it looks. If you decide that it doesn't look good enough, but you're still not ready to invest in a screen, you can always buy projector screen paint (such as Screen Goo) and apply it to your wall to create an "on-wall screen".
 

· Premium Member
Joined
·
9,579 Posts
You do not EVER want to use keystone adjustment on a theatre projector!! Power point in a convention hall is fine but the distortion and artifacts are awful!!
Easy there, fella! :eek: First of all, I initially stated:
(You want to avoid keystone adjustment as much as possible.)
The comment you quoted was one of THREE options to gain more room below the screen - on the assumption that a) he was going to be using a screen and b) he was going to place a center speaker below it - and I clearly said "a little bit" because, as pointed out above, I know that keystone adjustment is to be avoided.

Jeez...

You are far, far better off tilting the screen forward or back a little ...
Seeing as how the OP states that he will be projecting onto his wall, you may want to explain to him how to tilt his wall forward or back a little. ;)
 

· Premium Member
Joined
·
9,579 Posts
There is no such thing as a "little bit" of digital keystone adjustment. The instant it is applied, the artifacts appear.
There is such a thing as a "little bit" of digital keystone. I use a "little bit" of digital keystone. Not only did I not notice any artifacts the instant I applied it, but I haven't noticed any artifacts at any time since then.

Let me re-iterate:
eljay said:
(You want to avoid keystone adjustment as much as possible.)
 

· Premium Member
Joined
·
9,579 Posts
Apply ANY amount of keystone correction and watch what happens!!
My projector currently does apply ANY amount of keystone adjustment to the images it projects. It's just a "little bit", mind you - only 2 or 3 points out of 100 (or whatever the scale is), just enough to "square" the bottom corners with the screen - but the images I see on my screen are perfect.

I understand that keystone is to be avoided. Hell, I even STATED that keystone is to be avoided. But if it makes you happy, here goes:

To the OP: Never, ever, ever use keystone adjustment. Ever! :eek:
 

· Premium Member
Joined
·
9,579 Posts
It's too bad that your eyesight isn't good enough to perceive the moire artifacts caused by digital keystone correction, which are unavoidable. You could have saved money and bought a cheaper projector.
My projector and my eyes work great for movies. I don't sit around watching moiré patterns.

Prove me wrong ...
That's funny. First you take a cheap shot at me, and then you expect me to do something for you. What a joker. :rolleyes:
 
1 - 13 of 13 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top