CurtPalme.com Home Theater Forum

jeffslife · Joined: 17 Apr 2010 Posts: 4190 Location: ohio usa

So,
I am doing my set up from scratch according to the sony manual.
I have a ceiling mounted front projected g70.
The manual says the optical angle of the pj has to be from
3 degrees to 15 degrees plus or minus 5%.
I know how to measure angles and I have a protractor, but I have no
idea where to pick up a straight edge from to check the angle.
It appears to be about 12 degrees from my perspective.
Is this angle measurement really that critical?

virusc · Joined: 11 Apr 2007 Posts: 358 Location: Massachusetts

that is the angle range. From factory I think the angle is around 12 degrees like you measured (CRT's and lenses assuming chassis is on flat surface) If the bracket is level on ceiling then you have factory 12 degree angle.

It is also important that the projector is squared to the screen. This will effect lense focus and convergence if not very close to squared.

ecrabb · Posted: Thu Oct 07, 2010 4:45 pm Post subject:

Jeff,

That spec is the throw angle range and it has to do with the electronics' keystone range and the optical scheimpflug's focus range. Just make sure you're in the ballpark; you don't need to know the actual exact angle for any reason. If you can get the scheimpflug focused, and you've got plenty of keystone for perfect geometry, you're good to go.

Unless you were doing a really small screen or had a really high ceiling, you shouldn't have a problem, anyway. I think I'm in the 10-12-degree ballpark, as are most of us with typical 7-8 foot screens and 8-foot ceilings.

SC

jeffslife · Joined: 17 Apr 2010 Posts: 4190 Location: ohio usa

Great, Thanks for the info, I didnt understand why, now I know.
I am trying to understand this stuff so as I go along I can comprehend
the whole set up better.I dont mean to be a pain in the *** but I
will never get a good picture without some help.The manual sometimes
tells you what to do but not so much how to do it.
I wish I was more Tech savvy but im just not, thus I bother you guys.
I am trying to keep it at a minimum, but I really want to get this right.
I hope everybody understands.
Thanks

Artinaz · Joined: 15 Jun 2009 Posts: 110 Location: SF Bay Area

What I usually do is make sure the projector is level- both from front side-to-side and front-back. Once done, you essentially mount the screen so that center of screen matches the crosshatch from the projector.

After that, even if you need to make changes after you are done convergence or change in resolution, you will be in the ballpark where you can use keystone etc to take care of it.

Azi