02-10-2015, 08:29 PM
I can tell based on the MTF chart. Maybe I should save the particulars for the future but for a centered system the only non chromatic aberration permitted on the optical axis is spherical aberration. Based on the implied slope between 10 and 30lp/mm at the leftmost position on the graph I can tell with some degree of accuracy the quantity of spherical aberration in the system.
The 'bumps' in any one image plane (i.e sagittal or meridonal) are shifts in the balance of the aberrations. A system without an asphere that has a "nice" design free of pupil aberrations will smoothly degrade towards the corners and maybe experience a local min and then rise in performance again thanks to vignetting. I am ignoring them and assuming they are fluctuations in the higher order spherical aberration. The lower order coma and higher order spherical continue to degrade performance towards the edges until about the 20mm position where the meridonal plane drops off a cliff - this is most likely higher order coma and the "net" is strong astigmatism, but in general the resolution in the meridonal and sagittal planes remains quite similar so astigmatism is okay.
I'll save more for the future =)
The 'bumps' in any one image plane (i.e sagittal or meridonal) are shifts in the balance of the aberrations. A system without an asphere that has a "nice" design free of pupil aberrations will smoothly degrade towards the corners and maybe experience a local min and then rise in performance again thanks to vignetting. I am ignoring them and assuming they are fluctuations in the higher order spherical aberration. The lower order coma and higher order spherical continue to degrade performance towards the edges until about the 20mm position where the meridonal plane drops off a cliff - this is most likely higher order coma and the "net" is strong astigmatism, but in general the resolution in the meridonal and sagittal planes remains quite similar so astigmatism is okay.
I'll save more for the future =)