Quote:
Originally Posted by yelvertoft
Hugh,
This means that the wide open aperture at the 50mm end is f/4 but at the 500mm end, the maximum aperture (without the teleconvertor) is f/6.3.
Duncan
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Duncan's concept is right as always but a small glitch.
I am not sure about kenko's TC as I don't have that but when using my 50-500mm with Sigma's 2x TC, you lose a physical length of lens from lower focal length, due to protruding opticals in TC, into true hallow end lumen of lens, so in effect, you can have the benefits of 2x only from original 100 to 500mm focal lengths and you lose the 50-100mm of original (Non magnified) lens' focal length.
You do loss some quality (Not too much though) with converter, but it's up to situation and you to decide if it worth.
Nevertheless this is one very very unique lens that seems to keep its place firmly despite several years of manufacturing as no other company even the giant ones, have dared to make a competitor in this range.
Two things I don't like about the lens:
1- Squeaky sound sometimes comes out of motor while AFing but it seems to be a benign sound that needs to be tolerated only.
2- Large filter size that makes every filter virtually a wallet destroyer and lack of rear end slot for smaller drop in filters.
Otherwise one wonderful lens that makes you quit proud when in use with exceptional result most of time.