If you don't use a tripod, you can get better quality if you move closer to the subject. Actually even if you do use a tripod, it won't be as good as without the converter.

1.4 is better than 2.0 because you only loose one stop of light. Faster lenses are better with converters because autofocus doesn't work as well if there isn't enough light.

Larry ... Im new in this hobby I own a Nikon D200 with a 18-70 and the old nikon 70-210....and I would like something longer for outdoors /wildlife... would you recomend on getting one ..
Thanks again
Paul

With the 1.4 magnification factor, you're already at 300mm with the 200 zoom. How much longer do you want to go, and do you own a sturdy tripod?

Also, there is a difference in teleconverter optics and I would recommend Nikon's own over any third party one.

I will add that in all the years I owned the two Nikon teleconverters, (TC-14 and TC-200) I think I only used them once, and that was combined with the 500 f4P to make it a 1400mm lens.

If it's something you find yourself using often, consider getting a single focal length lens because the image quality difference will be night and day. Older 300 f2.8 lenses had excellent optics and can be had for reasonable prices now.

Tele converters were almost a necessity many years ago when very long lenses of any quality were rare and unusually expensive. The leading camera companies even offered 1.4 or 1.5 converters specifically matched to a particular lens. I used one with a 50-300mm zoom and it was a viable way to work shooting motor racing.

But eventually companies like Sigma began offering very long, 400 and 500mm APO tele lenses that were quite sharp with good contrast for quite reasonable prices. I used a Sigma APO tele 400mm for a number of years and obtained very good performance from it. Getting a good very long lens for a decent price that works is particularly appealing I think because for most photographers they don't have a use for it that often.

I have a Sigma 2X newest model and Have to say its ok. But the drawback is consider some of these you have to go manual focus as well. most the 1.7 and under as long as they support the newer computerized cameras will autofocus.
I find mine are usefull on bright days that I can get away with loosing that Fstop/s to make up for it.
Overall buying a lense to do the job is always best. less potential damage when exposing your camera during change outs.
Should you decide on buying one consider research the specs on them and email the company if you can't find the answer/s.

Cheers!
NikonMeister