Complex sentence: None of these lenses equal the Iscorama range optically, and all suffer from relatively high levels of chromatic aberration, but they do offer superior vignetting characteristics thanks to their large rear anamorphic elements and pancake designs.
Split into simpler sentences: None of these lenses equal the Iscorama range optically, and all suffer from relatively high levels of chromatic aberration. They do, however, offer superior vignetting performance thanks to their large rear anamorphic elements and pancake designs.