Originally posted by scratchpaddy The "Bigma" nickname is also used on the cheaper 150-500mm, but they get bigger. Much bigger.
That's a constant-aperture lens, f/2.8 all the way to 500mm. Of course, I don't have it, and I wouldn't even if I had $26,000 to burn.
I know it's off topic, but with a lens that size, I think I'd just use a telescope and get even more telephoto.
Anyway, I always thought the Bigma was for the 50-500 mm Sigma lens (or possibly any Sigma that goes out to 500 mm). Thus the "Big". A smaller zoom Sigma is just a Sigma.
As for the aperture, I do believe the aperture shown is just a function of the digital camera's "resolution" in reading f-stops (with regard to whether you are adjusting in 1/3, 1/2, or 1-stop increments). If the camera is wide open, it will actually be some value that matches up with the fixed diameter of the lens and the actual focal length. It would seem that it might be easy to actually calculate what the real aperture is at any focal length and see how well it matches up with the display. I'm sure if someone is bored they could do that math quickly in Excel.