need help
 

I got a new nikon d3000 for christmas and I have 2 lenses; 18-55mm and a 55-200mm. So far so good, I'm happy with the set up. I will be taking a trip to Alaska this summer and I'm wondering if I have enough magnification for the types of pictures that I'll be taking. Can I add a 2x to my 55-200mm or should I just get a different lens? Thanks for the input.
Mike

you would not want to put a converter of any magnification on a consumer grade telephoto, let alone a 2x converter.

if you really require the additional magnification, you would need to get another lens.

what does your trip entail?

Hi, the trip is a mixture of fishing on the Naknek river with a trip to Brook Falls, the famous bear spot, a Denali bus tour then down to Homer for a Halibut trip. A mixture of several different types of pictures.
Thanks,
Mike

In addition to doubling the focal length of a lens, a 2X teleconverter adds two stops to the maximum aperture of a lens. Your f/5.6 lenses become f/11 lenses, and your D3000 will refuse to autofocus. If you need a longer lens, get a longer lens.

Tamron's 70-300 Di LD (~$165) is nice and inexpensive, but it's not stabilized like your other lenses. Sigma has a stabilized version of their 70-300 (~$400), but it's new and not much is known about it. Nikon has a stabilized 70-300 (~$540) and Sigma has a stabilized 120-400 (~$900) that are both very good.

How much do you have to spend?

Sigma also has a 150-500 (~1,000) that is very similar in design and optic quality to the 120-400 TCAV mentioned that will give you even more reach if you need it.