AVS Forum banner
Status
Not open for further replies.
1 - 17 of 17 Posts

·
Registered
Joined
·
855 Posts
Discussion Starter · #1 ·
Well one thing leads to another.


I posted earlier about having my 150 project a picture where the right side was noticeably higher than the left side.


Well since then I can't stop myself from verifying that this is no longer happening.


That problem has not reoccurred but I measured the projected image and the right side is roughly 3/4 of an inch higher on the right side than the left. This is from an image being projected from 12 feet.


I believe this to have been true from day one but I wasn't picking up on it before.


Is this type of geometry distortion within norm for a DLP projector or is this something that should be fixed?


Anyone else ever experienced this type of issue?




------------------

Every man is my superior, in that I may learn from him.
 

·
Premium Member
Joined
·
24,984 Posts
Is your projector perfectly level from side to side?


------------------

Noah


[This message has been edited by noah katz (edited 08-30-2001).]
 

·
Registered
Joined
·
363 Posts
Check the attitude (orientation) of the projector to the screen: pitch, yaw and roll. The projector is analogous to the space shuttle on this page .

Make sure you are not projecting the image at an angle. If you have a side wall perpendicular to the screen use it to make sure the distance between the wall and center of the projector lens equals the distance between the wall and center of the screen.
 

·
Registered
Joined
·
16,014 Posts
The height of my image is shorter on the left side by about the same amount as you're seeing, Lou. I noticed this early on and thought that I must not have the projector oriented correctly in relation to the screen. I tried everything to change the position of the projector in attempts to correct it with no success. I suspect it's due to an internal misalignment. I've been debating whether to send my projector in for service.


I wonder if this is an uncommon problem and you and I are the only unlucky recipients of it? Or instead it's more common but others haven't noticed it?


Bob


------------------

~ The Sultan of Cheap ~


[This message has been edited by RobertWood (edited 08-30-2001).]
 

·
Registered
Joined
·
855 Posts
Discussion Starter · #5 ·
Robert I am seeing the same thing as you. My post is badly worded. Currently the left side of the image is about 3/4 of a inch shorter than the right hand side.


I have checked the level of the screen and projector and both are OK. Referring to the link Signal sent me - it looks like the YAW of the screen maybe the problem. The screen is slightly closer on the right hand towards the viewing location than the left side. I'll play with adjusting the projector accordingly.


Probably the easiest test would be to project something close up and verify that the geometry of the projected image is correct.


Will followup with an update post shortly.


Damn and after consciously avoiding looking for rainbows etc this pops up!



------------------

Every man is my superior, in that I may learn from him.


[This message has been edited by Lou Sytsma (edited 08-30-2001).]
 

·
Registered
Joined
·
363 Posts
Ah... so that is what it is.

I keep shifting mine to over come this. It's not so bad on the Wall but I can see how it would be an issue on a screen...


Miles



------------------

My System Config
 

·
Registered
Joined
·
855 Posts
Discussion Starter · #7 ·
Miles - are you experiencing the same thing?


------------------

Every man is my superior, in that I may learn from him.
 

·
Registered
Joined
·
93 Posts


Apart from the screen and the projector being perfectly level, the projector should also be perfectly perpendicular to the screen.


I initially had this problem because the wall where I mounted my screen was not at right angles with my LT150 (one side was nearer resulting in a shorter image border). Re-orienting the screen or the projector should correct this.


If not, then your projector does have a problem.
 

·
Registered
Joined
·
363 Posts
Lou, I'm not entirely sure. I haven't run any test patterns... and with young kids the table gets moved occasionally. What I did notice a couple of times is the image ( when I thought the projector was straight) would be "higher" (ie running up from left to right) on the right hand side, I have been correcting this by moving the projector... I'll check it out, it sounds like I maybe experieincing the same issue...


Miles



------------------

My System Config
 

·
Registered
Joined
·
45 Posts
My LT150 displays one-half inch higher on the left side than the right side. Since mine is ceiling mounted, I noticed that the adapter plate the projector connects to is not perfectly flat; it is slightly curved upwards on the left side. I guess I will try to flatten that.


What I'm going to do is project the blue image and use a level to see if the image is off.


It's a hard life being a perfectionist...
 

·
Registered
Joined
·
16,014 Posts
I suppose it's possible that what I'm seeing is resulting from my screen not being perfectly perpendicular to the projector. I'll check that out today. What's making me think that's not the case, though, is that I've used the same screen (hanging in the same position) with my DILA. And I didn't have a difference in image height on one side then. At least I don't think so. Maybe I failed to notice it.


Bob


------------------

~ The Sultan of Cheap ~
 

·
Registered
Joined
·
408 Posts
You guys might be onto something here. My projector is ceiling mounted, and despite using a level at the time of install, I thought that the image was a tad high on the left side when projected on my screen. My solution was to correct with the mount. It's no longer a problem.


Kirk


BTW, I use a 90" diagonal 4:3 screen.
 

·
Registered
Joined
·
855 Posts
Discussion Starter · #13 ·
Jonmx - you nailed it! Rotating my projector to the left corrected the image and straightened the geometry out.


Looks much better.


Note - I recommend avoid using the leveling arm found underneath the projector at the front. It is made of plastic and when deployed causes the projector to tilt slightly. These small errors manifest themselves into larger ones when the image displayed is so large.


Ah well - mark it down as a lesson learned for a FP newbie.


Thanks to everyone who replied!


------------------

Every man is my superior, in that I may learn from him.
 

·
Registered
Joined
·
16,014 Posts
I'm another newbie who has now learned a lesson.

Thanks, guys.

I put up a tripod mounted screen so I would be able to easily adjust the position of both projector and screen.

With that the left and right of the picture can be made the same height. So sure enough my geometry problem was apparently being caused by my retractable screen not being mounted perpendicular to the projector.


BTW, Lou. That's a good signature you have. Whose words are those?


Bob


------------------

~ The Sultan of Cheap ~


[This message has been edited by RobertWood (edited 08-30-2001).]
 

·
Registered
Joined
·
855 Posts
Discussion Starter · #15 ·
Robert - I don't remember who the quote is from.


I just remembering hearing it once on an episode of All in the Family.




------------------

Every man is my superior, in that I may learn from him.
 

·
Registered
Joined
·
956 Posts
Quote:
Originally posted by Lou Sytsma:
Robert I am seeing the same thing as you. My post is badly worded. Currently the left side of the image is about 3/4 of a inch shorter than the right hand side.


[...] The screen is slightly closer on the right hand towards the viewing location than the left side. I'll play with adjusting the projector accordingly.

(Italics added by me for emphasis.)


Lou, the above statements are a little confusing to me. If the screen is closer to your viewing area on the right side, the picture should also be shorter on the right side, not the left side. Can you verify which side has the shorter image and which side is closer? If indeed the left image side is shorter but the right screen side is closer, there almost has to be some kind of alignment problem.



------------------

Paul Heroy

[email protected]


[This message has been edited by pheroy (edited 08-30-2001).]
 

·
Registered
Joined
·
2,099 Posts
It sounds like a horizontal keystoning where the projector is not lined up perfectly in the center of the screen. If you point the projector against a wall and turn it to the left or to the right a hair that is exactly what will happen to the image.
 
1 - 17 of 17 Posts
Status
Not open for further replies.
Top