I mounted the fresnal lense separate from the pir on my most recent cam using the RS-49-525 PIR. I am getting really lousy distance...maybe 15 feet. Anybody know offhand the ideal distance from the lense to the sensor. I waded through the post last night and couldn't find it. Seems like the ms20 was 7/8" to 1" and the lamson was 1/2" to 5/8" couldn't fing a post specific to the RS pir. I experimented some but can't seem to get much improvement on this.