kappaknight
Well-known member
- Joined
- Sep 13, 2024
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- Atlanta, Georgia
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- Cyberbeast

This is great! I thought of the exact same idea just haven't done the experiment to make it work.
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Like most trucks, if you have a big load, you can't use your rearview mirror. This has never bothered me because I have two side mirrors that show what's behind me. Same thing with panel vans and box trucks (you can never use a rear view mirror because there is no rear window).This is the answer to this question. I think everyone is over thinking it. Just use the mirror.
OK. This is one of my more goofy projects considering you can buy a backup camera for $100. However, it works. Basically it solves the problem of not having a rearview camera when the tailgate is down. I experienced this when I was carrying a full sized bed with the tonneau cover down. I only had my side mirrors and could not see if anyone was directly behind me.
This is a 3d print which holds some acrylic mirrors in a penta-prism arrangement such that it will reflect the camera view rearward when the tailgate is down and still have an upright image.
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Image is somewhat degraded but it is still very useable - certainly better than nothing.
Image with tailgate up:
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Image with tailgate down and "prism" installed:
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I have uploaded the model if anyone wants to make one for themselves. Can be downloaded here:
https://www.printables.com/model/980116-cybertruck-tailgate-camera-prism
The bungees are just for a backup. The primary connection mechanism is the magnets. But anyway, here is the side profile diagram with dimension (in mm). The dotted lines trace light coming in from the top and bouncing off the two mirrors and then exiting on the right (where the camera sits). I just added a constraint in the cad file that the reflected angles must be equal to the incident angles at each mirror and the exit must be perpendicular to the input. The CAD tool (Fusion360), then, solved for everything. You can see the answer it came up with (fx: 67.5 degrees).Hi. The idea of the penta-prism is brilliant. I would like to make one of these boxes out of fiberglass, with a snap-on feature rather than the bunji cord. Is there any chance you could post the actual dimensions in a diagram (end-on, in particular)? I realize it is either 300 millimeters or 12' of mirror, but the angles seem important. Those stl files do not have dimensions, and are perspective-view (warped in a viewer), so hard to unravel. TY. )))
Does FSD work with prism and the tailgate down? My CT keeps warning me that the tailgate is down and FSD says auto steer is unavailable.OK. This is one of my more goofy projects considering you can buy a backup camera for $100. However, it works. Basically it solves the problem of not having a rearview camera when the tailgate is down. I experienced this when I was carrying a full sized bed with the tonneau cover down. I only had my side mirrors and could not see if anyone was directly behind me.
This is a 3d print which holds some acrylic mirrors in a penta-prism arrangement such that it will reflect the camera view rearward when the tailgate is down and still have an upright image.
![]()
Image is somewhat degraded but it is still very useable - certainly better than nothing.
Image with tailgate up:
![]()
Image with tailgate down and "prism" installed:
![]()
I have uploaded the model if anyone wants to make one for themselves. Can be downloaded here:
https://www.printables.com/model/980116-cybertruck-tailgate-camera-prism
Me too.I would be thrilled if this also works with FSD
Seems unlikely it would. If they allowed it it would likely require recalibrating the cameras but I suspect it is automatically disabled if the tailgate is down.Does FSD work with prism and the tailgate down? My CT keeps warning me that the tailgate is down and FSD says auto steer is unavailable.
I wouldn't mind the rear camera turned off if FSD would still work while the tailgate is down. I can use the mirrors and other cameras for the rear view. Hopefully Tesla decides to allow FSD to work with the tailgate down. I'm sure Tesla could do it with an OTA update.Seems unlikely it would. If they allowed it it would likely require recalibrating the cameras but I suspect it is automatically disabled if the tailgate is down.
I have no problem with not being able to have a rear view camera. I can drive with side mirrors. My problem is FSD being shut off when the tailgate is down. Turning the rear camera off doesn't allow FSD to work. I can drive safer if FSD is allow to work with the tailgate down. I wouldn't think rear views are necessary for FSD to work, but maybe it is. If it is, Tesla could put the rear camera in the bumper area below the open tailgate.Like most trucks, if you have a big load, you can't use your rearview mirror. This has never bothered me because I have two side mirrors that show what's behind me. Same thing with panel vans and box trucks (you can never use a rear view mirror because there is no rear window).
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This load blocked the rearview mirror but left the rear camera unobstructed.
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This load blocked the rearview mirror and the rearview camera. A camera on the rear of the roof would have been blocked too.
I've been using pickups to haul various loads my entire life and ALL PICKUP TRUCKS ARE LIKE THIS!
Sorry for shouting, but the amount of ignorance I've seen posted about seeing behind you is shocking to me. I guess we have a lot of people brand new to pickups here, but they need to realize this is nothing new and people have been driving perfectly safely for decades without a rearview mirror. The side view mirrors are more than adequate (just as they have always been).
If anything, the Cybertrucks driving dynamics when fully loaded make a rear view mirror even less necessary than ever. In the under-powered and under-suspended trucks I drove in my youth, we would often be going slow enough that traffic would build up behind us. But guess what? Even in that situation the side mirrors worked fine.
I can't understand all the people with rear view mirror fetishes. It's concerning. It makes me not want to be on the road with other motorists. Do people not understand safe driving and how to maintain awareness of what's going on around your vehicle?
BTW, I'm not removing my rearview mirror, it's most useful for viewing back seat passengers and it's never obstructed my views forward or too the side. I wouldn't cry if it were not there, but I'm not going to remove it, even though it's dead simple to do so.
I suspect it relies on that camera to detect cars passing in adjacent lanes reliably. Imagine a car flying up behind you and only getting into the passing lane at the last moment. FSD would not see this car until too late if it decided to start a lane change. I also suspect that, even with a camera recalibration, my mirror solution would not work. I conveniently only showed how it looks in the rearview mirror mode where it zooms into a portion of the cameras full field of view. If you bring up the full camera view, a significant portion of the field of view is blocked. FSD won't know what to make of that.I wouldn't mind the rear camera turned off if FSD would still work while the tailgate is down. I can use the mirrors and other cameras for the rear view. Hopefully Tesla decides to allow FSD to work with the tailgate down. I'm sure Tesla could do it with an OTA update.
I'm a builder and I'm planning a 3000 mile trip to pick up one hundred 10' sheets of clear polycarbonate that would easily fit in the vault with the tailgate down. I would really like FSD to work for that trip.