Always out of focus. Why?

Raindrops refract light. A double rainbow is perceptible when a double refraction occurs in the drops; in the second one the colours appear in reverse order.

Trying to capture the vibrant colours of a rainbow is utterly difficult. It does not seem to matter how the camera is set. A camera cannot register how a prism refracts the light and what I see. I get the same result over and over again, a rainbow out of focus.
Why?
The bow does not have a specific place; it has only a direction - like the wind.

Anna Carlgren