50-500 teleconverter question

[bballboy30]

I am planning on buying the sigma 50-500 lens and want to know how it works with the sigma 1.4x teleconverter. I read the teleconverter sticky and learned the two are compatible. However, I also read that the zoom range is restricted between 100-500mm. What exactly does this this mean? Does it mean that the max zoom even with a teleconverter is 500mm? If so what would be the point of a teleconverter with this lens?

Thanks.
Alex

[Naytwan]

I think that means the maximum you can zoom the lens is from 100-500, so it would be 140-700 with the tele convertor on. You couldn't go down to 50.

Correct me if I'm wrong though, but that's what I figure.

[blackviolet]

yes, that's correct with the sigma tc, and any others that have a bit of a protrusion. you need to lock it off at 100 to prevent the rear element from impacting on the tc. with the tamron sp tc (the white one) which does not have the protrusion, you can go down to 50.
i wouldn't recommend it with any crappy (like the tamron non-sp) or 'generic' teleconvertors, as they are *really* soft.

it's also important to point out that you will not have af. i don't recommend the 'tape trick' as the lens will hunt big time! (note: on a 1 series body and the tamron sp with centre spot af in bright light, af does work, sorta...)