Canon U.S.A. Inc., to Provide 120 EF 400mm f/2.8L IS II USM Lenses for Expansion of the Dragonfly Telephoto Array Project

[BeenThere]

I wonder what the advantage of using camera lenses over telescopes is for astronomy. 6" aperture telescopes can be had pretty inexpensively.

Stacking them gives extremely large aperture for the focal length. Much dimmer light collected.

 

[ColorBlindBat]

If my brain is working today, they should end up with an effective aperture of ~0.22.

 

[Kit.]

I wonder what the advantage of using camera lenses over telescopes is for astronomy. 6" aperture telescopes can be had pretty inexpensively.

The formal rationale is very low lens flare of these particular lenses. Dragonfly studies galactic halos, they need optics with very low scatter.