On Wed, 24 Jul 2002 20:29:29 -0600, Joseph Tainter wrote:

>I'm looking to add better close-focusing ability to the Sigma 70-200
>F2.8 APO I just bought, and would prefer to keep autofocus and the same
>max aperture (i.e., I don't want to use the 1.4x extender or a macro
>tube). This seems to be the only two-element close-up lens in 77 mm.
>size, but it sure costs.
>
>Has anyone tried it? Experiences?

It is an achromat, and should be as good as any
close-up lens on the Sigma (I suspect that by
f5.6 or so, results will be excellent, and with
zooms [which are more focus-distance sensitive
than most non-zooms for sharpness] that an
achromat will give better results than tubes).
BTW, with close-up lenses, considerably smaller
sizes can be used (with step-down rings)
without vignetting...