In article <32F5DB37.3943@outinohio.com>, fhawk@outinohio.com says...
[probably a good idea to not cut off the name of the author of quote...]
>> You've got to be kidding! Nikon TCs are a pain exactly *because* they
>> are designed to be optimally compatible with the lenses. Try using one
>> of those "one size fits all" 3rd party TC's on many a Nikon telephoto and
>> discover the dark corners in your images. I've never tested Tokina
>> converters, but my results show that the Nikon converters just blow the
>> tamrons out of the water optically. The results may be *ok* with a
>> Tamron, but compare the same image taken with a Nikon TC and you will
>> understand what I mean.

>No teleconverter (TC) is going to provide the same optical quality as the
>lens on its own. In addition, Nikon doesn't even make a TC that's fully >compatible with some of their better zooms (the 80-200mm f/2.8 D comes to >mind). Check your Nikon TC compatibility chart and you'll note that many >lenses are indicated as having vignetting or other performance >limitations--I've contacted Nikon, and in most cases they've said that the >original lens must be stopped down to f/8 or f/11 or slower to avoid
>vignetting--so now you've got a really slow lens (once you factor in the
>TC) and still risk getting "dark edges".
>Then factor in the cost of the TC, and you'd be better off buying a used
>slower MF telephoto lens--since that's all you're going to end up with--even >if you start with a fast, expensive, AF zoom.
[and it might be good if you and others shortened your lines - saves editing]

While what you say is technically true, this sharpness fanatic owns
and uses five (5) different Nikon teleconverters... When their advantages/disadvantages/appropriate-uses are understood, they can
provide fine images. Some of my favorite combinations: TC14C + 80-200
f2.8; 16 (fisheye) + TC14A; 70-210 E + TC14A; 500 f8 (older) + TC14;
300 f4/f2.8 or 400 f3.5 + TC14C or TC300/301; any macro lens + TC(any);
TC14C + PB-4 + 150mm enlarging lens. A good TC, combined with a compatible
lens, can result in fine images, easily made, with a compact lens system.
Hope This Helps