CurtPalme.com Home Theater Forum

Douma · Joined: 05 May 2006 Posts: 57

I have a 'like new' Barco Cine 7. Because my ceiling is too low, I can't mount the projector like it should, with the standard angle of 10.5 degrees. So I want to mount it on an 0 degrees angle. If I enter this data in LENS it gives me 0mm of vertical scheimpflug correction and 0.337mm of horizontal correction.

Is this correction with or without the 'three positions' spacer of the Cine 7?

betel · Posted: Sun Jul 25, 2010 1:42 pm Post subject:

Assuming front projection:
I've been told if what you're trying to do is what I think you are, the image will reflect back into the lens causing image problems. Not sure what problems though. Have you considered floor mounting?

Ile

**AnalogRocks** · Posted: Mon Jul 26, 2010 12:13 am Post subject:

Or you can tilt the screen 10.5 degrees

JustGreg · Joined: 07 Mar 2006 Posts: 3098 Location: Kenosha, WI

You'll also be wearing a pyramid shaped pattern in the phosphor. I'm battling the same thing. If I lower the pj the rear riser center seat will only be able to accomodate short people. If I don't, my new tubes will have a weird raster wear pattern.
Sorry rear center seat person! Mr. Green

ecrabb · Posted: Mon Jul 26, 2010 7:10 am Post subject:

Greg - Mounting the projector in the typical position most of us use them in results in the trapezoidal wear... A zero-degree offset will result in a perfectly rectangular raster and wear pattern.

The only way to use a zero-degree offset is if the projector is mounted straight out from the center of the screen... So, if the center of your screen is 3 feet from the ceiling, so would the center of the lenses be. Needless to say, not many people use a 0-deg offset.

I don't know enough about the Scheimpflug setup on the Barco Cine 7, but I would think you'd probably want to stay with the default offset, and drop the rear of the projector a little, and tilt the screen a little. You may have to do some shimming on the lenses to get best top/bottom focus if you don't have stepless Schempflug.

My G70 is flush against the ceiling at the front of the projector, but about 2-3" away from the ceiling at the back - that was to get the projection centered on my screen, which is probably only 3' from the ceiling. You have to tilt the screen or use stepless Scheimpflug to get focus ideal, but it works.

SC

roland@b4 · Joined: 07 Jul 2009 Posts: 82 Location: Reading UK

Leave the spacers on the mid position
As already said the projector would normally point up at 10.5 degrees so even if your projector is completley on AXIS you will need to lift the back of the machien. (where the case splits gives you the vertical centre line view along that to get centre of screen)
Asuming your projector is on a tall table mount then you will have to place some spacers (a series of spring washers will give you variable adjustment) between the rear of the top of the lens and the tube mount.
Then just use those big plastic bolts/nuts to adjust the top bottom focus.

JustGreg · Joined: 07 Mar 2006 Posts: 3098 Location: Kenosha, WI

Phil Smith · Joined: 08 Mar 2006 Posts: 7717

I tilted the screen of my RP setup to reduce the angle to about 7 degrees. That surprisingly reduced the trapezoid shape of the raster a LOT, much more than I expected. At least for a G70, this was not a problem but a big plus. I'm sure Steve has similar results by dropping the back of his G70.

Not to state the obvious, but Scheimpflug is compensating for the angle of the tubes. Reducing that angle requires you to reduce the amount of Scheimpflug compensation. That can't help but be a good thing if your PJ can handle it.

Not real clear, but you can see the angle in my screen in this pic:

kschmit2 · Posted: Wed Jul 28, 2010 5:51 pm Post subject:

Phil Smith · Joined: 08 Mar 2006 Posts: 7717

Yes but you can reduce the angle of a FP PJ by dropping the back like Steve did. That does however require the screen to be mounted higher.

I wasn't able to do a zero degree RP setup because the PJ is mounted in the garage. I needed the garage to still function as a garage.

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

Phil,

that garage-RP is pretty cool, and quite inventive. I've never seen anybody do anything like that before (use a garage as a hushbox), but it does answer the question of what do you do with all the space behind a huge RPTV. Smile

I see you even provided doors for rear-access to the back of your A/V gear. That's definitely thinking outside the box.

With the PJ being in the (heated?) garage, did you ever run into any problems that resulted from that mounting location? (Debris in the air, fumes, lights from the wife pulling her car in at night... Very Happy

)

stefuel · Posted: Sat Jul 31, 2010 10:37 am Post subject:

This sounds like one of those situations where a factory authorized dealer/installer would come in and say NOPE. The application is not suitable for the installation of a CRT projector and refuse the job.

Post a couple of pictures of the room showing where you want the projector and screen to end up. A picture is worth a thousand words.

Douma · Joined: 05 May 2006 Posts: 57

Thanks for all the replies. After some more calculation I ended up with a projection angle of 8 degrees. I removed the scheimpflug rings and according to the output of LENS I fitted the right amount of small washers.
The Barco now has it's own custom made ceiling mount and hangs rocksteady.

So it was a case of tempest in a tea pot. Sadly I ran into some other problems after the first rough setup:
http://www.curtpalme.com/forum/viewtopic.php?p=262185#262185