In article
>I am trying to find out what closeup lenses are available.
>Specifically, I am looking for a two-element closeup lens to fit
>55 mm filter diameter. I am aware that Nikon makes several
>(3T, 4T, 5T, and 6T) of different strength and filter size, but
>want to know if there are any other two-element closeup lenses
>made by other manufacturers.
I think Nikon, Canon, Minolta, Leitz, and Sigma (for the 90 macro,
52mm thread) all make them. Both step-up and moderate step-down
rings can be used to fit them to your thread size without vignetting.
Hope This Helps