CurtPalme.com Home Theater Forum

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

Hi,
My 9PG+ is mounted vertically with a mirror about it. With the mirror at 45 degrees the image was way to high so I lowered the picture by tilting the mirror more than 45 degrees. Now I try to focus (mechanical) I can get the vertical lines to focus fine as well as the horizontal lines near the bottom of the picture. As you get more and more away from the bottom of the picture, the horizontal lines get more and more out of focus. It is the same for all three colors. From my experience with a sony 1292, this seems to be an astigmatism problem. I can't correct for the angle by using the two plastic tabs next to each lens.

I'm asking for options at this point. The only solution that I can think of is buying some very thin washers and using them to slightly tilt the lenses. I tried tilting the top of the screen away from the wall but it made the problem worse. I can't destroy the wall. Tilting the bottom out would allow me to get uniform horizontal focus however I would only be able to focus the vertical line OR the horizontal lines. The only other thing that I can think of would be to lower my mirror closer to the lenses which would allow me to tilt the mirror up a bit but I'm not sure if it would be enough. It would be a pain to more the mirror straight down so I'd rather leave that as a last resort.

If any of you have any ideas, please post! Thanks,

-Greg

stefuel · Posted: Sun Nov 02, 2008 1:28 am Post subject:

I think your in for a fight. You've probably picked the worst projector to attempt a mirror project. If it had continuous lens flapping you might stand a chance.

**Curt Palme** · Posted: Sun Nov 02, 2008 2:19 am Post subject:

Yep, it does have flapping tabs, but you need to loosen the lenses each time you adjust. That is what it is though, and hopefully if you get a tab setting correct for one tube, the other two will have the same settings.

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

My problem is that those tabs are meant for a range of 0 degrees to 11 degrees up. I have some unknown angle down which they aren't meant for. I've played with multiple tab positions to no significant effect. I just got some washers so I'm going to start playing with those. I've have to take the lenses off each and every time now.....

I'll play with just the green and if I get it to work then I'll copy it for the others.

-Greg

kschmit2 · Posted: Sun Nov 02, 2008 9:13 am Post subject:

You could try to replace the flapping rings by (strong) springs, and use something like black foam to block light from leaking to the sides.
That would allow you to tweak flapping much more easily.

The Projector is designed for either 0° or 11° projection angle. You get probably +-1.5 degree of leeway through the flapping adjustments. Primarily those adjustments are meant to allow you to get better side focus on different screen widths though (more or less lens toe-in necessitates those aditional adjustments to achieve optimal focus).

Kai

stefuel · Posted: Sun Nov 02, 2008 11:02 am Post subject:

I just re-read the original post. The problem seems to me to be that the mirror tilt is now incorrect. Tilting the mirror down to compensate for height is the same as tilting down a ceiling mounted projector which increases the projection angle. A NEC does not like that. I think the solution is to put the mirror back to 45 degrees and drop the mirror down closer to the PJ/floor to lower the projected image. For a NEC to mechanically focus correctly, the base of the projector must be at the correct height and 90 degrees to the screen. To maintain the correct geometry you can only bend the image with a 45 degree angled mirror. If you go to the A site and do a search in the archives (5-7 years ago) when NEC PG's were the hot item, you will find many posts about the importance of getting a PG's mounting dead on to get perfect optical focus.

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

I played with various washers for about 3 hours last night and if I solved one problem I created another. Maybe if I spend days at it it would eventually work but I don't have that much patience.

Putting the mirror back at 45 degrees would send the image too high even if I lower the mirror. Would 56 degrees work? Tilting the mirror is like raising the back of the projector to get a zero projection angle so I might be able to get away with 45 + 11 = 56 degrees. Let me know if I'm thinking of this wrong.

Thanks for all your help so far,
-Greg

kschmit2 · Posted: Sun Nov 02, 2008 6:28 pm Post subject:

wouldn't it be 45 + 5.5?

stefuel · Posted: Sun Nov 02, 2008 10:24 pm Post subject:

"I played with various washers for about 3 hours last night and if I solved one problem I created another. Maybe if I spend days at it it would eventually work but I don't have that much patience."

This is why I said you'd "be in for a fight" but hey, don't listen to me. I'm just a wack-o with a AmPro...

grogthegreat · Joined: 16 May 2007 Posts: 166 Location: San Diego, CA

I knew that I'd be in for a fight but I can't give up before trying. I've never actually seen an AmPro. Would you mind if I see yours when I'm back in MA for winter break?

kschmit2: Thanks. It really is 45 + 5.5 = 50.5 degrees. I had to draw a picture before I could see why....
Know I'll have to figure out a way to measure 50.5 degrees. I'll probably have to cut out some sort of triangle already at that angle.

Thanks again,
-Greg