AVS Forum Special Member
Join Date: Jun 2005
Location: Northern, VA - Washington, DC
Mentioned: 102 Post(s)
Tagged: 2 Thread(s)
Quoted: 1645 Post(s)
Not sure how I missed this thread...
In the initial photos, the lens is CLEARLY not centered left/right to the screen.
To adjust the left/right position you want the top and bottom of the test pattern to be perfectly aligned with the top/bottom of the screen.
Being off by a couple of inches results in the top/bottom lines not being parallel as you can see in the photo. The top line is dropping a bit to the left.
To correct this, the projector (since it has no left/right lens shift) must physically be moved towards the side which is smaller. Only by about an inch or so.
Check again to see if the top/bottom edges are parallel. Repeat this process until the lens is perfectly centered left/right.
Now, you adjust the height.
The 3550 should offer a bit of up/down lens shift. Similar to the HT2050A. It's rated at 10% which means that the lens should be able to have about 5" of range on a 100" diagonal image. A bit more for 120" diagonal.
In the past, this has meant that the lens could be about 3" to 8" above the top of the screen (when ceiling mounted) and the target was always about 5" above the top of the screen. So, if your screen is 15" from the top of the ceiling, then the center of the lens should be 10" from the top of the ceiling. This is, generally speaking, ideal for this particular model.
Now, you are on center and your lens is 5" above the top of the screen. But, the lines are not parallel to each other.
In your photo, they clearly bow outwards towards the bottom. This means that the projector is pointed downward slightly.
Tilt the projector up, then use lens shift to shift the image downward until it is on screen.
Check again and see if the lines are parallel.
Repeat this process until the lines are parallel to each other. Always tilt the projector in the direction that is smaller. Then lens shift back until the image is on screen.
Obviously, if you need to physically move a projector left or right after you've already bolted it into the ceiling and your projector mount puts the center of the lens 10" above the top of the screen when you only are allowed to go 8" above the top, you are going to have some placement issues. Then you get into keystone correction, the drop in image quality that goes along with that, and a lot of personal choices. In my view, you shall not use keystone correction. You shall put a projector where it belongs. Proper projector placement is critical to best image quality and I didn't just drop $1,000+ on an image that I'm willing to compromise image quality on. But, that's my choice and doesn't have to be yours.
There are plenty of quality mounts which offer very precise height flexibility.
There are not many mounts with good left/right adjustability.
I ALWAYS take my projector to the top of a ladder, upside down, plug it in, and run a test pattern on screen to ensure I have proper left/right placement ahead of mounting it to the ceiling. If I'm within about an inch, I typically can tweak it close with the mount to get it perfect.
I wish you luck if you continue further down this path.
AV Integrated - Theater, whole house audio, and technology installation in the Washington DC metro area.