Resolution Question

Hello all. Didn't know where to post this so chose this forum since none of the others seemed appropriate.

My question is if optical resolution behaves the same way that radio resolution does. As we know, with radio telescopes if you build an array or have two scopes separated by some distance, the resolution of the combination of scopes is determined by the baseline of their separation.

Would optical scopes behave similarly? So in a practical example, if I had a 20" Newtonian, if I placed a mask with two 3" apertures with the outside of the holes 20" apart (i.e., the centers 17" apart), what would be the theoretical resolution of this masked setup vs the full resolution of the 20" opening?

The theoretical resolution for infinite contrast objects would be that of a larger scope, but only in one dimension if you used only two holes. Tough luck.

If you make four holes, you have just invented the newtonian with four extremely thick curved spider vanes and a large central obstruction - the theoretical resolution limit may seem interesting, but you're likely to throw enough energy into the diffraction rings for the scope to really not perform very well visually (especially if you want to look at low contrast features on anything).

Use an infinity of 3" apertures arranged at the edge, and you have the 20" aperture with a 14" central obstruction (with very much the same consequences).

The question is: what do you want to do with the aperture?

To fully understand the performance, you should look at the Modulation Transfer Function across all frequencies, not just the fixed "resolution", and you'll see that you can't obscure a sizeable portion of the aperture's area with complete impunity.