On Sat, 22 Aug 1998 20:30:46 GMT, danksta@ns.sympatico.ca (Terry Danks) wrote:

>I am about to order a 1.4X teleconverter to
>use with my 500mm f/8 Nikkor mirror.
>
>The TC-14B ($535) is "Useable if the rear screw-in
>filter is removed" according to the Nikon catalog.
>
>The TC-14A($250) is "Useable but there is occasional
>vignetting"
>
>The price difference is very much a concern. How
>severe and "occasional" is the vignetting likely to
>be. Will it be more pronounced at infinity or close-ups?
>Will it be so slight that mild cropping would make it
>a non-concern? Is there a difference in the central
>image quality between these two TC's, i.e., is the
>14B better all-round?
>I will not likely be using it with AF lenses.
>
>Any help MOST appreciated here.

The following refers to the older-style, larger, non-macro
version of the Nikkor 500mm f8 mirror - which I prefer
for its slightly better performance...
The TC14A does work, but it is not quite so good on
the Nikkor 500 as the TC14/14B, and it appears to lose
more than the one stop one would expect from a 1.4X
converter. I never saw evidence of vignetting with it.
I suggest looking for a used TC14 - it is optically the
same as the "B", but non-AI*S* (no big deal), and it is
often far cheaper than the "B" (I've bought two for
about $100 each...). The older Nikkor 500 f8 plus TC14
is a surprisingly good performer - quite sharp to the
corners, and the TC removes the usual mirror "hot spot".
I just leave the converter on my 500 and consider it
a very compact (though slow...) quite good 700mm...
BTW, if you ever get an 80-200mm f2.8, 300mm f4, etc.,
the TC14 is also excellent with these. BTW, you may find
interesting my Nikkor evaluation list, which includes the
TCs (on my web page, under "I babble").