How is the virtual image formed (photo-graphed) by a camera ?

Can a virtual image by photograph by a camera ?

What is a virtual image ?

How does the lens form an image ?

We cannot decide the image distance in the case of virtual image formed by lenses. Is above statement correct or incorrect ? Explain with reasons.

Where are images formed in the eye?

A lens forms real and virtual images of an object, when the object is at u_(1) and u_(2) distance respectively. If the size of the virtual image is double that of the real image, then the focal length of the lens is (take, the magnification of the real image as m)