Angular Resolution: Best Possible Observing Distance for Stars

[intervoxel]

Supposing a perfect optical instrument, what is the best angular resolution possible when observing distant stars?

 

[Filip Larsen]

You may want to read up on the concept of "diffraction limited telescope".

 

[Drakkith]

Supposing a perfect optical instrument, what is the best angular resolution possible when observing distant stars?

The depends almost entirely upon the diameter of the aperture and the wavelength you are asking about.

http://en.wikipedia.org/wiki/Airy_disk

 

[zhermes]

The previous answers are entirely correct, but also note that ground-based telescopes (as apposed to space-based) are often more limited by 'seeing' than the diffraction limit. Atmospheric Seeing is deterioration of the signal based on variations (turbulence, etc) in the atmosphere.