[madpoet]

Anyone have any advice on getting a precise point for ceiling mounting? Since I have to remount my projector again this weekend, the wife would REALLY appreciate me not putting more holes in the ceiling . WIth no lens shift, it needs to be square to the screen and at a fairly accurate (to the inch) distance. The room isn't exactly square, so it's going to be a royal pain.


Thanks,

MP

 

[Rob Ricket]

MP,


You can't go wrong if you use a plumb bob. Place ur PJ on a ladder, (Use a couple of spacer blocks under the PJ if mouted upside down) and move the PJ into position. Next, move the plumb bob till its over the desired mounting hole and mark your spot.

 

[JHarri1972]

Or, if your worried about the ladder idea.....


Make a perfect square inside of your room with strings tied to something like small nails in your ceiling (check by ensuring equal diagnals). Measure to the center point of your screen from your now squared off room; mark that point; pound a nail in the ceiling there. Measure the same distance at the back of your room and pound another nail there. Run another string between these two nails. Now you have a line that runs perpendicular to your screen. Mount the projector so that the lens center sits along this string line at a point within your throw range keeping in mind that lens center and projector center aren't always at the same location.


I did this same thing a month ago, mounting my projector before the screen. I was about 1/4" off when the screen went up. Well within the tolerance of my ceiling mount....Good luck.

 

[DaveInBerlinNJ]

(a*a)+(b*b)=(c*c)


"a" is ONE-HALF screen width

"b" is distance from center of lens to center of screen

"c" is length from center of lens to edge of screen


You should know a and b, so solve for c.

Make two strings the exact length of c.

Attach strings to opposite edges of screen... where the loose ends of string meet in front of screen is where the center of lens should be!


This will get you centered and square horizontally. You'll have to handle the vertical issue!


Here's a hypotenuse calculator:
http://www.farfarfar.com/ed/hypotenuse.html


(consider "a" to be side 1, and "b" to be side 2... "c" is the hypotenuse)


...or you can just make holes!

 

[madpoet]

Ahhhhh... math. I knew there was a reason I slept through those classes


Thanks guys, it gives me a good working point.


-MP