doubleelementclose-uplenses

... double-element close-up lens. Double-element lenses have two elements and are also called dual-element or achromatic close-up lenses. The second element ...

The close-up lens is screwed on to the front of a lens like a filter. This lens has two achromatic elements to correct chromatic aberrations.

2011年12月12日 — Sometimes called dual-element or achromatic close-up lenses, these lenses have two elements; the second corrects the aberrations of the first.

NC Macro Close-Up Lens II 77-72-67mm ; Double apochromatic optical element ; Multi-Nano Coating® NiSi (NC) treatment, for better sharpness and easy cleaning from ...

Single element close-up lenses are relatively inexpensive and may be adequate for occasional use, but they are not as good as their double element equivalents.