Sandhill Cranes must be one of the most photographed birds at the Reifel Bird Sanctuary, but that does not mean they are any less interesting to photograph. While this example of the crane does not place the bird in the most exciting pose, it does show the capabilities of a lens and teleconverter combo I have been working with.
I paired a recently acquired Sigma APO 120-300mm F2.8 with the Sigma APO EX DG 2X TC this past week to see how well the combo would work in practice. As with the lens, I did some bargain hunting and found the TC used in mint condition for half the price of a new one. So how does this combination work with the Nikon D800? So far I'd say the results are mixed. I like that the combo gives me the ability to have more reach, without having to spend over $9000 on a 600mm F4, but there are issues that come along with working this way.
The Sigma APO EX DG TC X2 has several notable effects when used on the 120-300mm F2.8. First, it gives more reach, making it a 240-600mm F5.6 lens. So the biggest hit the user will take is the reduced availability of light that comes with using a 2X TC. Second, there is a slight loss of contrast and sharpness. The loss of sharpness seems to be magnified by the distance from the subject. Close subjects, those that are less than 30m away, are sharper. It is also a good idea to keep the subject near the center of the frame and crop a little to get the composition right, since the edges are where the softness is most noticeable. None the less most images could be improved without too much effort in post.