[ISL]

The edge should be quite sharp. Any deformation or movement in the edge will be smoothed extremely quickly, on timescales comparable to the light-crossing time of the object -- in this case ten seconds or so.

If you're a photon and you're in, you stay in. If you're out and heading out, you get out. (if you skim the surface, you might make an orbit and then leave :) ). It is that fact that makes the edge quite sharp.

[sandworm101]

I disagree. The edge of a BH is essentially an asymptote. While there is a mathematical bright line, when looking at it you should see light in all manner of red/blue-shifted colors near the event horizon. Since that light is coming in from a variety of directions it leaves in a variety of directions too. Everything would look soft and fuzzy around the edges. Out of focus.

[codethief]

Out of focus? I don't know about you but I find the black hole "edge" in the simulated images in Interstellar quite sharp.

(Or are you talking about resolving matter/light near the event horizon? In that case I agree – one won't really resolve any structures anymore due to light getting bent and redshifted in a myriad of ways.)

[codethief]

An observer at infinity won't see anything cross the horizon, though, by the very definition of what a horizon is.

[SiempreViernes]

The light crossing time refers to the time needed to traverse a diameter of distance.

[codethief]

Sorry, I misread.