After a solid month of agonizing over which telephoto zoom I wanted, I finally settled on the Sigma 100-300 f/4. I chose the Sigma for a few reasons. A) It has a constant f/4 aperture throughout the entire zoom, which makes it suitable for low light conditions. B) It has internal focusing so the front element does not rotate. This makes using a circular polarizer much easier. C) The zoom is also internal, so the the length of the lens doesn't change as you zoom in or out. D)It has the HSM motor, so the auto focus is fast and silent. My first impression of this lens it that it is huge!! As you can see in the picture above, it makes my Nikon D300 look like a toy. This lens is is 13" long with the lens hood, weighs over 3lbs and takes an 82mm filter. Being from the EX line, the build quality is excellent. It feels very solid in the hand and the adjustment rings feel very smooth. I haven't had of a chance to use it yet, but I will be giving it a proper work out next week in Costa Rica! I have heard nothing but good things about the performance of this lens, so I am excited to get it out in the field. I also bought the matching 1.4X tc, so that will give me an effective focal length of 420mm @ F/5.6. If you are interested in learning more about this lens, you can visit the Sigma website at http://www.sigma-photo.com/lenses/lenses_all_details.asp?id=3273&navigator=3. Stay tuned for some image samples!
