The number of elements necessary for a quality teleconverter depends on the
magnification level of the TC. For 1.4x TCs, 4 or 5 elements are
sufficient. Hence, the Zuiko 1.4x TC sports 5 elements. For 2x TCs, what
Jim said is true. I don't think there ever was a quality 3x TC made.
Regards,
John
----- Original Message -----
From: "Jim Couch" <JamesBCouch@xxxxxxxxxxxxx>
> The 7 element Vivitar has a much better reputation than the 4 element.
> with teleconvertors the 7 element convertors are generally better. The
> extra elements allow for better correction of various aberrations.
>
> Jim Couch
>
> William Clark wrote:
>
> >
> >
> > Hey all,
> >
> > I just noticed that my 2 Vivitar MC teleconverters are a bit
> > different. I have the Macro-focusing one (7 elements in 5 groups) and
> > a non-macro one with 4 elements in 4 groups (both teleconverters are
> > 2X). Which one is better? I am not sure what an extra group and more
> > elements give you. Would the extra group impede light transfer in
> > astrophotography? Thanks for any help....
> >
> > -Bill
>
>
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>
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