Researchers make telescope from ten Canon 400mm lenses

Researchers at the University of Toronto have developed a telescope called Dragonfly that uses ten Canon 400mm f/2.8 L IS II USM lenses. The system is intended to detect objects with very low brightness.

The Dragonfly Telephoto Array, as the telescope is called in full, is a system of ten aligned camera lenses mounted in an aluminum frame on a robotic arm. The lenses used are Canon 400mm f/2.8 L IS II USM lenses, currently available commercially from 9800 euros. A SBIG STF8300 camera is mounted behind each lens. The professional monochrome cameras each have an 8.3 megapixel four thirds sensor from Kodak and are intended for astrophotography. Lens and camera are linked together with a lens controller, which controls the autofocus. The whole system weighs about eighty kilos without the wishbone.

The system is set up by means of interconnected computers, which run software written by the researchers. The user only needs to set the desired observation targets on the main computer and download the data at the end of the evening. The system also works automatically; the main computer uses weather data to determine whether data can be collected and then sends commands to the other computers that control the cameras. The main computer controls the position of the robot arm and the lens focus.

The telescope is being used to find out how large structures in the universe, such as galaxies, have formed. According to the current cold dark matter theory, large galaxies grow from the clumping of smaller ones. The scientific evidence for this is formed by structures and deformations that arise during this growth.

While such distortions have been observed in some galaxies, such as our own Milky Way, scientists have not yet found them in many other galaxies. According to the scientists, one explanation could be that current telescopes scatter the light too much to make the predicted structures visible. The Canon lenses in the Dragonfly have a special nano-coating in the lens that reduces light scattering inside the lens. Therefore, according to the researchers, this telescope is ten times as effective as the first competitor at detecting astronomical objects with very low brightness.

The system started in 2013 with three lenses and has gradually expanded to ten. The telescope is set up at the New Mexico Skies Observatory in the US. The New Mexico location is more suitable for astronomy than Toronto due to its elevation of 2200m above sea level and much lower light pollution.