Large blind space behind rearview mirror

[Dale Mahalko]

Regarding the issue of legality and view obstruction, apparently it is not necessary for a rearview dashcam to be fitted completely behind the mirror.

Because you are looking into the rearview mirror at an angle, the distance the mirror is away from the windshield projects a "blind space" shadow behind it, that actually extends out and away from the mirror and is slightly larger than the mirror itself.

So the working space for where the cameras can be located is actually larger than the rearview mirror, but varies a bit depending on the height of the driver.

A tall driver looks straight into the mirror at a level angle, or while a short driver looks upwards into mirror, which shifts the blind area up and down. Also seat position of short vs tall drivers shifts the shadow slightly left and right.

The difficulty for dashcam manufacturers to make use of this area and attach their camera to the rearview mirror mount, is that this blind space offset is reversed for left-hand or right-hand drive vehicles.

 

[Ukraine Visitor]

Regarding the issue of legality and view obstruction, apparently it is not necessary for a rearview dashcam to be fitted completely behind the mirror...

Just a comment: For me, and perhaps others, a primary motivation to fit a regular dashcam (i.e., non-rearview mirror dashcam) completely behind the OEM rearview mirror is so that it can be as stealthy as possible.

A regular dashcam that is mounted/pasted/glued/etc onto any other area of the front windshield than that limited area behind the rear view mirror (RVM) will be much more easily spotted by drivers in front of your car than one that is located behind the RVM. Note that because the spotting of a dashcam so mounted is given from the perspective of the driver in front of you, "behind the RVM" in this context does not match 100% with the "behind the RVM" area of the windshield from your perspective as the driver of your vehicle, and which deals with the issue of legality/view obstruction that you addressed.

Considering this, IMO, the ideal location for a regular dashcam is one that gives you "the best of both worlds". Such ideal location is (I will try not to get too mathematical here) that area of the windshield formed by the intersection of the area that is "behind the RVM" from the your perspective as the driver of the car containing the dashcam and the area that is "behind the RVM" (or, more precisely, in front of the RVM) from the perspective of the driver of the car in front of you as he looks at you via his own RVM.

Just a comment.

 

[sludgeguts]

Which is why, whenever there has been a thread about ideal cameras, some of us harp on about a tiny lens on the end of a tube (as per Innovv c3)

, one in the front, one in the rear, both connected to a central control box - so why on earth did they put the K1 lens into an ugly cube?
The C3's bullet shaped lens has so many discrete mounting solutions.

 

[Nigel]

So the working space for where the cameras can be located is actually larger than the rearview mirror, but varies a bit depending on the height of the driver.

I think legally, it should have to be in a suitable position for use by all drivers of all heights so actually the area is a lot smaller. When our cars get tested, they don't ask the height of the driver so that they can check visibility!

However, a dashcam does not need to be behind the mirror, the only rules we have in UK are that a video screen should not be visible to the driver while driving, although there seem to be exceptions these days since reversing cameras are accepted so probably the live view of a dashcam would be accepted too, and nothing should obscure visibility beyond 4cm into the area swept by the wipers - there are a lot of dashcams that can fit the lens within the 4cm area, but no power cables hanging down!

 

[sludgeguts]

It's acceptable to have sight of a screen which displays information about the car or its immediate surroundings (such as reversing cams or blind spot cams (as seen on coaches, trucks etc to watch for cyclists - the screen for these tend to be sited away from where you would normally be looking whilst driving along). It's also acceptable to have satnav screens since the information on them is graphic rather than actual.