Star Trails at a [Not-] Random Place in the Sky, M11 as "The North Pole"
From Adam Block:
"The intersection of art and science springs from imaginative curiosity. What happens if a camera is rotating at the back of a telescope while capturing a picture of a beautiful star cluster? Each star will trace a circle around the field- literal deep-space star trails! By painting star light circularly, the colors of stars are much easier to discern. In addition, many stars are at the same radial distance from the center and as the camera turns their light is mixed producing wonderful hues of a stellar rainbow. The spacing of the circles also clearly shows the density of the stars and how quickly that increases towards the center of the cluster. [You can see the mouse-over image HERE. You can see the video HERE.]
When coupling a mechanical device with gears (the rotator) to a large optical system- the simple idea of rotating the camera during an exposure to achieve this result is a challenge! Getting the system to rotate precisely 360 degrees was just the beginning. There are apparently some optical variations regarding rotating an image through different filters. Neither stars nor traces aligned through each filter! The variations of magnification, for example, were on the order of 0.04%. Although seemingly small... this variance was enough to make a perfect idea a big practical problem."