What is the reason to change the mount type in Nikon 1 series?

Question

To use Nikon F-mount lenses, Nikon 1 series require an adapter.

Moreover, the flash unit mount is a custom one too and it seems that there is no adapter at all, but maybe I'm wrong.

What is the technical reason to use custom mounts for this new brand, while there are obvious disadvantages of not keeping the mount which already exists for a half of a century, and the hot shoe which is largely compatible with most manufacturers?

Answer

The Nikon SLR lenses are designed such that the image circle falls on the sensor/film plane based on the distance from the sensor to the mount (flange focal distance). For an SLR, this distance includes the space needed for the mirror. As the Nikon V1 doesn't have a mirror, the distance from the sensor to the mount point is substantially smaller, so in order to use an SLR lens you need an adapter to create the distance. This adapter does just that.

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