I made a 16:9 screen out of a 4x8 Parkland Plastic sheet. 48"x(16/9) = 85 1/3 inches.
I probably should have used 1x4 to frame the back so I could have 2" under the sheet & 2" uncovered for mounting the 2" base shoe I chose as a surround. This would have given me all 48x85 inches. Instead I framed with 1x2 with the plastic sandwiched between the frame and molding.
85.3 - 4 = 81.3
48 - 4 = 44
81.3/44 = 1.85 oops!
It didn't *look* like the aspect ratio was changing, but if you draw some pictures with much more exaggerated borders than 1/24th of height, you'll see that rectangles become skinnier as the border gets thicker.
I should have made the screen 44*1.78=78.22 inside, 82.22" outside length. Doing it over, I wouldn't use a frame (and a R 5.6 foam insulation sheet backing, 3M 77 spray-glued down), but a solid sheet of plywood or maybe masonite+frame. Parkland Plastic is too flexible, but too hard to "tension" as you would with a fabric screen to get all waves out.
-M
I probably should have used 1x4 to frame the back so I could have 2" under the sheet & 2" uncovered for mounting the 2" base shoe I chose as a surround. This would have given me all 48x85 inches. Instead I framed with 1x2 with the plastic sandwiched between the frame and molding.
85.3 - 4 = 81.3
48 - 4 = 44
81.3/44 = 1.85 oops!
It didn't *look* like the aspect ratio was changing, but if you draw some pictures with much more exaggerated borders than 1/24th of height, you'll see that rectangles become skinnier as the border gets thicker.
I should have made the screen 44*1.78=78.22 inside, 82.22" outside length. Doing it over, I wouldn't use a frame (and a R 5.6 foam insulation sheet backing, 3M 77 spray-glued down), but a solid sheet of plywood or maybe masonite+frame. Parkland Plastic is too flexible, but too hard to "tension" as you would with a fabric screen to get all waves out.
-M
