In the online instructions, it says that the achromatic lens should be flush with the aperture ring, but I'm having trouble telling when that condition is met. Is it the top or bottom of the lens flush with the top of the ring? What exactly should I be looking for when I check the alignment under the microscope. Also, I think some of our older scopes have the achromatic lens too high up in the body (right by the CMOS filter). Could this be the cause of some of our problems with our field of view being too small? Thanks!