The angular resolution of an interferometer telescope is a function of wavelength. I posted the formula in a previous post.

I think if astronomers tried to image something very far away, they would either require huge light collection area, or have to aim the telescope for a very long time. If it was far enough, or small enough, the telescope would be getting single photon counts per second, and not enough to actually create an image. Considering that things in this universe move around, if the telescope has to track a moving planet that is also rotating, there would be some minimum shutter speed required to snap a picture before everything smears out and is unrecognizable. If you want video, that's 30 frames per second, one photo every 0.0333 seconds. There would be some kind of inverse square law for radiative power emitted from an object which would also depend on wavelength. I bet there's a formula out there.