If they are over 1/2inch, they are too far apart. With finches, make sure you get birds that get along. Ask lots of questions and observe the birds if you can, or get them from a rescue or from a person who knows those birds. They can be very aggressive to each other and you could end up needing seperate cages for mean birds. Where I worked in the summer we always had small cages in our break room with singled out mean birds who couldn't be sold with others.