And the focus suddenly sits mostly right away ...

Once installed the TV screen on the basis of good guidance and with the help of the supplied tool within a minute I had first times sobering: That's it? A slightly darker viewfinder and nothing else ???

The eyes were then opened by means of an auto-focus lens capable with the following experiment:
- Enable all AF points in the camera.
- Lens switch to manual focus.
- Manually focus Try as much as possible on the center focus point.
- Half-pressing shutter release button.
Now Flashes the center AF point to red, you have taken the focus perfectly. Blinking other AF points or even not a single AF point on, you have focused next.

This experiment I have now tried with several lenses with different focal lengths and intensities once with the standard focusing screen EG-A and once with the offered here Mattscheibe EG-S at the Canon 6D. After having once made the installation, the change is within a few seconds.

Result:
- The EC-A I had a hit rate of about 10%.
- The EC-S, the hit rate was approximately 80%.

Only Ster drawback: The viewfinder is dark. But as dramatic as it is brought here by some reviews I did not find the darkening personally. The 24-105mm f / 4 I could even still focused fairly well in low light conditions. It is more difficult, however with fully manual lenses where the diaphragm is not set until the trigger. To f / 8 that's still reasonably, from f / 11 will be there as well in bright light heavy. It helps only a large aperture stop, focus, and then adjust the aperture value.

Finally, a tip: If the images after installation of the disc suddenly overexposed (or underexposed after dismantling), which is perhaps the fact that you forgot to set in the Custom Settings of the camera, the corresponding focusing screen.