Ronald and Almir,
I was chatting with Warren, one of our superstar engineers (they are all superstars really!), who also happens to be interested in astrophotography and has a small rig (Celestion C11 Schmidt-Cassegrain Telescope w/ Starizona Microtouch). Here's what he said about astrophotoraphy, light fields, and Lytro:
While there's no benefit for the viewer (since everything is at optical infinity), there is an advantage for the photographer. Focusing a telescope just right to get pin-point stars is one of the hardest tasks in astrophotography, and poor focus is one of the most common failure modes. I often spend 45 minutes painstakingly focusing my telescope before taking any actual photos, and sometimes it has to be re-done as the telescope changes temperature over the course of a long night. A lightfield camera would eliminate that task and really make astrophotography simpler.
That big advantage comes with a big price, though -- the pictures probably won't look as good as those taken with traditional cameras. The Lytro uses an array of microlenses to spread light out into component rays, which are then re-assembled in software to simulate any desired focal plane. That re-assembly cannot be perfect, even in theory, because the pixels on our sensors have finite size. That means that true point light sources, like stars, are one of our biggest challenges.
I would definitely encourage people to experiment with lightfield astrophotography -- I want to do some of it myself -- but serious astrophotographers will probably find that the costs outweigh the benefits.