Getting your projection straight?!

Sleazypants

Standard Member
Hello!

Newb to all this projector stuff. However, we've just bought an Optoma HD200X which works really well, and the picture quality is good.
We are projecting it onto a wall, and we're struggling to get the image straight. The only way the image can be straight is if the projector is sitting in one particular place. But that place is too low and would hit the sofa in the room.
So we've had to put it up a bit higher and tilt it down, but now the picture is slightly wonky on the top and sides.
How do i get it to straighten?
Also how does it work if i get a bracket for it to hang from the ceiling? Would that be the best option, because its then upside down and may not have this issue?
 

bravogolf

Active Member
If you're getting a trapezoid effect, where the image is larger at one side, it's because the project is physically at an angle, be it vertically or horizontally. You can either straighten the projector and use lens shift to move the image (which maintains the aspect ratio without the skewered look) or use keystone correction (which isn't recommended but certainly better than before). Or move the projector :)
 

bravogolf

Active Member
Just checked - you don't have lens shift but you do have keystone. I'd recommend simply moving the projector, you can get decent projector ceiling units or wall units
 

Sleazypants

Standard Member
Do you think it'd be straighter for us to ceiling mount it?
Because by the looks of it the ratio of the screen that comes from the top of the lens is more then the bottom (thus why the projector needs to be so low for the picture to be straight).. if that made any sense?! ha
So from my logic, if we turned it upside down and wall mounted it, it should straighten out?
 

custard10

Well-known Member
the main point with this projector is the fixed offset. so it has to sit above or below the screen by that offset. if above then it has to be upside down as you mentioned.

if you have already installed your screen then tell us its size and its distance from the ceiling and we can try and work out where best to position the projector.
 

ard126k

Active Member
Oh my, that looks extremely helpful. But i have no idea what any of that means?! ha

Look at the picture of the projector facing a screen. It shows the machine needs to be 25cm below the bottom edge of the screen. If it's mounted above the screen it needs to be 25cm above. Simples!

Dis you receive a manual with your projector?

Alex.
 

Sleazypants

Standard Member
the main point with this projector is the fixed offset. so it has to sit above or below the screen by that offset. if above then it has to be upside down as you mentioned.

if you have already installed your screen then tell us its size and its distance from the ceiling and we can try and work out where best to position the projector.

Well the screen is the wall, projecting straight onto the wall.
The distance from the projector to the wall is just under 11ft.

Look at the picture of the projector facing a screen. It shows the machine needs to be 25cm below the bottom edge of the screen. If it's mounted above the screen it needs to be 25cm above. Simples!

Dis you receive a manual with your projector?

Alex.

I adjusted it to say the projector is 11ft away from the wall, and i can see where it gives your the size of the projection. But it says 18cm (above or below the screen) instead of 25cm? I assume its because i hadnt told you the distance?

So basically, the screen on the wall is 84cm from the floor, so you're saying the projector needs to be 66cm from the floor. Which was too low and went behind the sofa so we raised it, thus having the trapezoid effect. SO! if we ceiling mount it.. the top of the screen is 49cm from the ceiling, therefore we'd need to mount the projector at 31cm for it to be straight?! Have i worked that out right? so at that 31cm, does the feet of the projector sit there, or the middle of the projector?
 
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Chox1988

Distinguished Member
So basically, the screen on the wall is 84cm from the floor, so you're saying the projector needs to be 66cm from the floor. Which was too low and went behind the sofa so we raised it, thus having the trapezoid effect. SO! if we ceiling mount it.. the top of the screen is 49cm from the ceiling, therefore we'd need to mount the projector at 31cm for it to be straight?! Have i worked that out right? so at that 31cm, does the feet of the projector sit there, or the middle of the projector?

Put simply, two options for a straight picture, floor or ceiling, all measurements are done to the centre of the projectors lens, Always line the centre of the lens up with the centre vertical line of the screeen-

1) Ceiling mount
If the front of the lens of the projector is 11feet away from the front of the screen then the middle of the lens needs to be 31cm from the ceiling.

Get a ceiling mount with variable drop between two amounts, say you could drop it between 20 and 40cm from the ceiling, this will give you room to work with fine adjustments, the projector has zoom so the horizontal distance between screen and it has a little bit of give but vertically there is no give, so line it up perfectly and get the height right are the key things.

Make sure you mount the thing to ceiling joists as straight to the plaster isn't the safest option, find the joists before drilling and hoping.

Sounds like a right pain but its worth it, went through all this a few weeks ago myself, couldnt be happier with the end result now.

2) Sat on the floor
Centre of the lens needs to be 66cm vertically from the bottom of the screen, assuming 11feet away, sat on a small table or something, but then you would have to sit behind it.
 

ManGina

Active Member
Sorry to hi jack this thread:blush:
I have a similar problem in that I want to prepare my room for the arrival of a projector but I dont know which model I'll get yet, although its likely to be JVC as these seem to be the best for my budget of 5-6k ish.
I want to put the pj on a shelf on my back wall, above where I'll be sitting. The front wall where the screen will go is around 14.5feet away.
I can center the mount ok but how high on the wall should I allow for the shelf to be? Is there an ideal or does it depend on the model in question.

I need to know roughly where to have my electric socket and hdmi leads on the wall.

Thanks for any advice.
 

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