Help Selecting Screen Size Please!

[Chip Gelmini]

I will soon start showing movies outside in my backyard.
The screen or wall for a screen does not exist.
I need suggestions getting the right size screen.
The air blown movie screens are measured “diagonally” which doesn’t make this easier.
The approximate distance is 26 to 30 feet from the back wall of the house.
Projectors remain inside the house. Standard Elmo super 8 lenses between the 1200HD and GS1200 are being used.
Looking for help selecting height and horizontal width.
Note: The bottom of the white surface must be 4 feet off the ground.
Suggestions of screen models for me to consider are greatly appreciated.
It does not have to be air blown.
Budget is limited. Trying to spend under $200.00.
Thanks in advance.

[Ed Gordon]

Chip, there are formulas to calculate the size of the image (see: Help with a home cinema design at the Film-Tech Cinema Systems web site).

Since the the only number you have to work with is the "26 to 30 feet" distance, what I would do is setup your projector somewhere and project onto a wall at say 10 feet from the projector, and then 15 feet from the projector. By measuring the size of the image when projected from different distances you can derive a formula to calculate the size of screen to get. The are portable screens available for less that $200. Here is one from Amazon for $87:

[Osi Osgood]

You might want to consider one of those " blow up" screens, usually used for projecting football games and such. They are designed for outdoor viewing and are usually quite affordable.

[Maurice Leakey]

Chip
Here is a link to the Owner Manual for the Elmo ST1200.
Scroll down to the projection charts for screen sizes against lens and throw distance.
ST1200HDOWNER.pdf (film-tech.com)