Not logged in
 
Author
Topic: Vertical offset
member
Joined: Jul 26, 2004
Posts: 4
Reply to PostAlert Moderator
Can’t seem to figure out vertical offset. It say 25’’ from center of Lens from top of image to center. I used your throw calculator. Pj is 12’ from screen. Screen is 92’’ diagonal. Height is 45’’. And screen is 12’’ from top of ceiling. Ceiling is not usual it is 7’6’’. Lens is 8’ from ceiling. My vertical offset is too short. Do I need to lower the pj mount from the ceiling. Octane the screen to the ceiling. Or both. Thanks I can make my screen bigger to 102’’ diagonal if needed.
moderator
Joined: Mar 28, 2005
Posts: 13,305
Reply to PostAlert Moderator
This projector has significant lens shift.

But your numbers in again, and pay attention to the section that discusses lens shift (below the main image).

The normal offset of this projector is 0. That means, it is in the dead center of the screen when lens shift is in the neutral position.

From there, with a 45" tall image, you may shift the image down or up 27". This means, that the lens can be as much as about 4" above the top of the screen, or as low as 4" under the bottom of the screen, or anywhere between.

If the center of your lens is 8" away from the ceiling, the TOP of the projected image can be no more than 12" away from the ceiling, but no lower.

If you use a larger image, you get a bit more lens shift range. But, not much more. Maybe an additional inch.

Not sure how far away you are sitting, but a 100" diagonal is a pretty small image by front projection standards. I certainly wouldn't go any smaller. Would get a 85" television instead.
AV Integrated - Theater, whole house audio, and technology consultation during the build and installation process in the Washington, DC metropolitan area.
member
Joined: Jul 26, 2004
Posts: 4
Reply to PostAlert Moderator
Quote (AV_Integrated on Dec 31, 2023 9:04 PM):
This projector has significant lens shift.

But your numbers in again, and pay attention to the section that discusses lens shift (below the main image).

The normal offset of this projector is 0. That means, it is in the dead center of the screen when lens shift is in the neutral position.

From there, with a 45" tall image, you may shift the image down or up 27". This means, that the lens can be as much as about 4" above the top of the screen, or as low as 4" under the bottom of the screen, or anywhere between.

If the center of your lens is 8" away from the ceiling, the TOP of the projected image can be no more than 12" away from the ceiling, but no lower.

If you use a larger image, you get a bit more lens shift range. But, not much more. Maybe an additional inch.

Not sure how far away you are sitting, but a 100" diagonal is a pretty small image by front projection standards. I certainly wouldn't go any smaller. Would get a 85" television instead.

Thanks so much for your response. Very helpful. I did not see the lens shift info previously. I have adjusted the picture it works. I adjusted the screen up. The lens is at 8" below ceiling and screen is 12" below ceiling. I could move the screen another 3"up. Epson 3800 was a gift and the screen was left by previous owner. I could always buy a bigger screen or paint the wall. 85" tv would be nice but since i already have the PJ why not use it. the diagonal of the white screen now is 90". Would lowering the PJ by 3" or 6" with an extension rod improve picture or give me more choices on size of screen. Thnaks
member
Joined: Jul 26, 2004
Posts: 4
Reply to PostAlert Moderator
Quote (AV_Integrated on Dec 31, 2023 9:04 PM):
This projector has significant lens shift.

But your numbers in again, and pay attention to the section that discusses lens shift (below the main image).

The normal offset of this projector is 0. That means, it is in the dead center of the screen when lens shift is in the neutral position.

From there, with a 45" tall image, you may shift the image down or up 27". This means, that the lens can be as much as about 4" above the top of the screen, or as low as 4" under the bottom of the screen, or anywhere between.

If the center of your lens is 8" away from the ceiling, the TOP of the projected image can be no more than 12" away from the ceiling, but no lower.

If you use a larger image, you get a bit more lens shift range. But, not much more. Maybe an additional inch.

Not sure how far away you are sitting, but a 100" diagonal is a pretty small image by front projection standards. I certainly wouldn't go any smaller. Would get a 85" television instead.

I also forgot to mention the HDMI cable is 40 feet long left.by previous owner. It is probably 12 years old. I assume I need to upgrade the HDMI cable for this projector which is 4k simulated. Maybe an upgraded active HDMI cable
moderator
Joined: Mar 28, 2005
Posts: 13,305
Reply to PostAlert Moderator
You want to be sure the projector is level and is near the top of the screen. That's kind of what is boils down to. You have a few inches above the top for maximum range, but that's about it. The calculator will give details, but I would avoid the 'max' lens shift that is available.

Throw distance is what determines what your screen size can be in conjunction with the zoom of the projector. This is also detailed on the throw distance calculator page.

For your HDMI cable, it is likely that the age of the cable will keep it from being capable of carrying 4K signals, which require HDMI 2.0 for best results. You can send the 3800 a 1080p signal over older cables and it shouldn't be an issue, but if you want to use modern 4K/HDR signals, you need a 18Gb/s rated HDMI 2.0 signal. I typically use those from RUIPRO that are fiber optic... and directional. Make sure you don't install it backwards.
[Edited by AV_Integrated on Jan 1, 2024 at 6:24 PM]
AV Integrated - Theater, whole house audio, and technology consultation during the build and installation process in the Washington, DC metropolitan area.