If the power of a lens is - 4.0 D, then it means that the lens is a

power 4dAFL's OPM5 and OPM4 Optical Power Meters for accurate fiber optic testing. Featuring Wave ID, rugged desn, and compatibility with various networks. ... -4D (Filtered-InGaAs) for hhAnswer:the power of a convex lens is always positive. as you can see here the power is +4D, therefore the nature of the lens is that it is a convex lens. we know, P = 1f. also