Sigma EX 70-200mm 2.8 mk1 for theatre photography

The "original" version was made in 1999 (?), and I'm not sure if it had HSM drive. The second one (before the macro versions) was made in 2005 - and those are the ones I pointed to I believe (one link is now broken). That for sure was a good lens.

If you really mean the original 1999 version (which I guess is what the photo looks like), then I'd sure check with Sigma as far as compatibility with your camera. I've heard of too many cases where the pre-digital cameras (before 2003) don't work or cannot be re-chipped to newer cameras.

But, I could be way off base here.