1=throw distance		example
	number=screen size	test at 10m	resulting image size
Elf lens	ratio guide	distance to screen	screen size at 10m
20mm	1 to 0.523	10	5.23
25mm	1 to 0.39	10	3.93
38mm	1 to 0.256	10	2.57
50mm	1 to 0.19	10	1.9
65mm	1 to 0.153	10	1.53
76mm	1 to 0.123	10	1.23
100mm	1 to 0.093	10	0.93