low budget alternative to backup camera

There have been a number of posts from folks wishing they had gotten the backup camera option. When I got HUMU in 2004, the camera was not an option so I looked into an alternative solution. I posted this sometime a few years ago, but now that the backup camera IS an option, and many are regretting not getting it, it might be worth posting again.

I went to an RV supply store and got one of those stick on Fresnel lenses; the flexible vinyl lens with the "record grooves" cut into one side that gives you very wide angle vision. Using manila folder paper as a pattern, I cut a piece that spans the vertical dimension of the lower rear window glass plus a quarter of an inch more creating a tab that fits into the very narrow slit between the glass and the frame on the lower portion of the rear window and helps hold it in place. You moisten the lens before the final installation and it stays in place indefinitely. Does not damage the defrosting wires. The lens is about eight inches wide and is pretty close to the center of the lower rear window so you can see a normal view on either side of the lens.

Observations:
1. You look through your rear view mirror, which keeps your eyes looking out and not at the MFD screen.
2. The Fresnel lens view is wide enough that you can see an object as close as three feet from the rear
and quite a bit further on either side. Better wide angle than the camera.
3. Because the lens is located in the rear window, you also have a normal view juxtaposed with the
Fresnel view. This is handy for parking and judging distance. Works when driving forward too.
4. If you are really nerdy, you can do what I did and use the wires in the defroster as a "ruler" to get an
even more accurate estimate. I used an orange traffic cone and positioned it so that the top touched
the upper defrosting wire and then measured the distance of the cone from the rear of the car. I did
this for each of the wires. When an object in my rear mirror view (looking through the lens) is
bisected by the upper wire it is 25 feet from the rear of the car; the next wire down = 9 feet; next
wire down is 6 feet and the bottom wire is 3 feet.
5. When cutting the vinyl lens, make sure the center of the concentric "grooves" lies in the center of
your paper pattern.
6. At one time, there were photos of this installation in the photo archives.