I've posted a few photos over the last several weeks using the Sigma APO 100-300/4 lens. I've been pretty pleased with the results, but still felt that I wished it could be a little longer.
Here's a shot (nothing real special) from yesterday (uncropped):
260mm......1/400 @f/5.6......ISO400
What's different about this photo is that I used the Sigma 1.4x DG EX teleconverter with it. That means the effective focal length is 1.5 x 260 x 1.4 = 550mm.
Here's a 1:1 crop:
I feel this combination will cover a fairly wide focal length (155-630mm) in a kit that is still lighter and much more compact than an equivalent dSLR combo.
The lens combo focuses very quickly and accurately.
R