Subal Close Up Diopter +4, 52 mm
The +4 diopters of this close-up lens are the right power for closer focusing with a 50mm lens (up to approximately 1:3) when you have reached the limit with the NL 2 lens. With 85mm (up to appr. 1:2.1) and 100mm (up to appr. 1:1.9) telephoto lenses, it is the highest power, and it should be used with the main lens stopped down to at least f/8.